Yet Another Cycling Forum
General Category => Freewheeling => Folders => Topic started by: rogerzilla on 04 September, 2009, 09:38:48 pm
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Anyone had their bushes replaced? How much did you pay, and did they ream them properly?
EDIT: Cyclecare Kensington - and Purton, near Swindon - can do it for £45, assuming no serious complications, and they have the reamer. CH White in Malmesbury don't have the tool.
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£45? ;D
Sod that. Looking at the replacement bush kit on SJS the bushes look like a H4 adjustable reamer size.
Which are available for £5 (the reamer that is).
A quick check anyway of the bushes with a vernier will soon reveal what reamer was needed. (it certainly won't be the one that's priced at £200.00 on SJS) ;D ;D ;D
I'm also confident of doing a much better job anyway. :smug:
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The factory charge £65 (including the retailer's cut). People have successfully done it using a standard reamer, but keeping the bores perfectly aligned on both sides is the tricky bit.
One day they'll wake up, smell the coffee, and use some sort of cartridge needle bearing.
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but keeping the bores perfectly aligned on both sides is the tricky bit.
I'd say that only such a small amount needs taking out that it's not really an issue.
This is evident by the replacement bushes not even being solid bronze phosphor ones.
As on the SJS site.
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One day they'll wake up, smell the coffee, and use some sort of cartridge needle bearing.
;D
They're made in Great Britain. I remember when that meant quality. ;D
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Could we contemplate a group purchase of the tool?
I'm happy to do the job for any forumites, or offer the workshop here for use, but even I can't justify the cost for the proper tool. Alternatively someone offers to hold it centrally and post it out as and when it needs to be used.
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Mine's towards the end of its third set
Both replacements done by Phoenix Cycles in Kensington(ish) at much less than Brompton wanted (can't recall how much, wasn't cheap)
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There are two tools; the removal tool is over £100 and the reamer is £200. The removal tool is only necessary if your old bushes are really, really stuck, otherwise people seem to get them out using a tap to grip them.
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I stumbled upon this (http://www.kinetics-online.co.uk/blog/?p=141) on Ben Cooper's Kinetics blog...
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Yeah, but after a few years you'll give up waiting and buy a new bike.
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Maybe that's part of the business plan.
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Both our Bromptons in England need replacement bushes, I'll need to replace the swingarm on my Brompton in Oz when I'm over there next and I have a tool fetish.
Any suggestions where I can purchase the stupidly overpriced tool? Nothing available from a quick web search.
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SJSC are out of stock, but I suppose any Brompton dealer can order one. If you haven't done the job before, don't underestimate the difficulty of drilling the heads off the s/s allen bolts - unless you get lucky and they actually unscrew. They are fitted with some never-to-be-undone threadlocker at the factory. The best technique I found was a hand cranked drill using all my weight and turning the chuck itself slowly. And lots of cheap Wilko HSS bits.
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What are the symptoms of bush replacement being required - play, noise, something else?
My Brom's started squeaking terribly, and though I haven't investigated yet I'd like to be prepared for the worst ... (Lightly used though, so I'd be disappointed if it needed serious work.)
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Mostly excessive play, though my Bromptons also develop an annoying squeak when pedalling.
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Bromptons aren't a quiet ride. Between the bell rattling, the chain noise and the various squeaks. It means people hear you coming.
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Don't forget the rattle of a Sturmey-Archer hub.
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Oh, yes, got used to the rattles, and the ticking, and quiet squeaks. It was the loud squeaks that were beginning to worry me, but they seem to have silenced themselves.
Little obvious play in the bushing as far as I could tell - maybe a mm or two lateral movement at the top of the swingarm if I tried quite hard.
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What are the symptoms of bush replacement being required - play, noise, something else?
My Brom's started squeaking terribly, and though I haven't investigated yet I'd like to be prepared for the worst ... (Lightly used though, so I'd be disappointed if it needed serious work.)
When mine started squeaking I tracked it down to the rubber suspension block needing some lubrication. The lube needed to go in the bolt hole through the centre of the block. I squirted a bit of silicone spray in there.
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Thread necromancy.
I've been looking at a friend's Brompton. He actually ended up buying a replacement bike, owing to the frightening repair bill from our (very good) LBS, and needing to be able to get to work. I don't think they gave him bad advice, but I'm trying to make sure I understand what's happened to his old one, as he's looking at selling it on either as is (as a project) or repaired (and to be honest, I'd find it a fun project to take on).
The problem is that the jobs are specialist, so it may have to go to a shop anyway.
So, the LBS were worried about the "lack of metal" in the hinge owing to wear (it's a pretty old model and has served him well). I've now seen that, and it's clearly play in the bushes. These are pretty-obviously this kind of thing (https://www.mcconveycycles.com/brompton-rear-hinge-bushing-kit.html) (his new Brompton looks to have nylon ones?) I'm aware of rust issues (https://yacf.co.uk/forum/index.php?topic=88474.0) in Bromptons, but I can't see any - this one looks good to me.
I can see from that page and this thread, though, that a shop equipped with spectacularly expensive tools is needed to replace the bushes. Any update on discussions here?
The other non-trivial job is a slipping seat-post, which I gather is tricky because of ungluing the old bush to replace that.
So that's the summary explanation I'm going to give. Anything I've missed or options I could give? If it ends up on eBay, he wants to give a fair summary, or if I have a go I don't want to take on anything I can't do (or turn down something I can).
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There is something on the interweb showing how to ream the bushes adequately with a standard fixed reamer. Brompton won't sell the proper reamer to anybody other than a Brompton-approved shop with a Brompton-trained mechanic.
I tried to pay to get on the Brompton mechanic's course so that I could buy the reamer but no dice. I'll just have to bite the bullet and do a ghetto bush replacement, after getting the frame components repainted. I'll fit a grease nipple for the pivot so that I'll never need to do it again. Unfortunately I'll probably have to replace the hinge pins to get it repainted.
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I'm not shy of mechanics.
I've built car and motorcycle engines (and pushbikes), and they have worked, for tens of thousands of miles.
But this thread, with insights of 'Brompton won't sell the proper reamer to anybody other than a Brompton-approved shop with a Brompton-trained mechanic.' make me think 'walk away, and pay to make it someone else's problem'.
It really goes against the grain, I've never been over-fond of anyone other than me spannering my ride, but in this instance, I'd be tempted to let Brompton (or one of their accredited dealers) get on with it.
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It's a bit puzzling really.
Brompton sell bush and spindle kits (https://www.evanscycles.com/brompton-rear-hinge-bush-spindle-kit-EV138989), which are quite widely stocked. These only make sense for the home mechanic, because a shop wouldn't need a new drill and Allen key every time. However, DIY fitting isn't recommended.
The guide mentioned by LWaB is probably the Shane Cycles (http://www.shanecycles.com/brompton-hinge-repair/) one. This makes it look quite possible as a DIY job. However, it's better to have a 9.5mm reamer (see comments on Shane Cycles blog) with a pilot (if I've understood reaming technology properly), because that allows the two sides to be reamed completely in line with each other. You're reaming the plastic inner of the bush, not the frame, so the reamer doesn't need to be that hardy. A 13/32-inch tap or similar is also needed, to extract the old bushes. Calhoun Cycles' photo story (http://www.calhouncycle.com/shopcast/?p=1827) illustrates the process.
Then you need something to do a job like a bearing press, to fit the new bushes. Shane Cycles used M6 threaded steel. It all sounds quite achievable, if you can source the reamer. Shane Cycles managed it with an over-sized reamer and no pilot.
Hmmm...
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I'd be concerned about the shop's comments about lack of metal at the hinge. If the bushes are left too long then the frame can get worn/deformed. A second opinion would probably be a good idea before deciding whether it's repairable or scrap.
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I'm pretty certain that the current bushes are the original, factory-fitted ones?
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I have the tap needed to remove the old bushes but have to get a stainless grease nipple and appropriate tap before swapping the bushes on my Brompton.
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So what reamer do you plan to use?
I was chatting to a friend today who is a very competent engineer (but not a cyclist). He wasn't sure how important precise alignment would be in a journal bearing for such an application, but said that, if it were him, he'd look to ream the bushes first, then fit them to the spindle, and only then fit them to the frame, as this should help with alignment.
He also said, interestingly, that the wear tends to be to the steel, because the softer parts flex rather than wear.
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A standard fixed reamer, unless I can find a proper Brompton reamer for sale somewhere in Europe for not more than £200.
Reaming before fitting the bushes is pointless as the bushes change internal dimensions as they are pushed into the frame. His method would work if the bushes were a close clearance fit and bonded in place. Having to push the bushes in from both sides also makes it difficult to fit them to the pivot before the frame.
He is right about wear to the pivot rather than the bushes.
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Interested in where you source the fixed reamer from, especially if you find one with a pilot - and in how you get on. Still think this is an interesting project.
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Ordered a Brompton reamer from outside the UK. It is all starting to come together.
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This thread is useless without pictures ;D
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The Cyclecare man said to me that new bushes don't always need reaming - he always tries the fit first. He's done two frames for me and ISTR that one wasn't ever reamed after rebushing.
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Maybe that answers my question?
It's a bit puzzling really.
Brompton sell bush and spindle kits (https://www.evanscycles.com/brompton-rear-hinge-bush-spindle-kit-EV138989), which are quite widely stocked. These only make sense for the home mechanic, because a shop wouldn't need a new drill and Allen key every time. However, DIY fitting isn't recommended.
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The semi-mythical Brompton reamer actually made it to my door. Who'da thunk?
https://pbs.twimg.com/media/C3QMN3QXAAAhihV?format=jpg&name=large
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Nice to see what one looks like :thumbsup:
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How much did it cost from the non-uk dealer?
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160 Euro plus postage. The package also had a tap to remove the old bushes, which I didn't know was included.
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Pricey! I've been meaning to change the bushes on mine for the last 3 years (!)... last time I started to have a go at it I couldn't rotate one of the hinge bolts so figured it must have been loctited to the rear frame (i.e. a messy loctite job that spilled over). Not sure what to do about that; I tried hitting an allen key with a hammer to loosen it but to no avail. The bike was bought second-hand so I don't have an option to have a dealer or brompton fix that.
Edit: then again, if that were the case it ought to be loctited to the powder coat and that should flake off under force. Which makes me wonder why I couldn't budge it last time I tried.
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The advice (http://www.shanecycles.com/brompton-hinge-repair/) seems to be that you may well need to drill it out. One place I've seen (https://chestercycling.wordpress.com/2012/08/29/brompton-rear-frame-replacement/) recommends a hairdryer or heat gun (mind the paint) to help break the seal on the Loctite on the bolts. Google for more advice.
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One day they'll wake up, smell the coffee, and use some sort of cartridge needle bearing.
;D
They're made in Great Britain. I remember when that meant quality. ;D
That was about 1851, no?
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Pricey!
Yes but I got annoyed enough to pay it anyway. Once our three Brommies have had their bushes replaced, it'll just about have paid its way.
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Pricey! I've been meaning to change the bushes on mine for the last 3 years (!)... last time I started to have a go at it I couldn't rotate one of the hinge bolts so figured it must have been loctited to the rear frame (i.e. a messy loctite job that spilled over). Not sure what to do about that; I tried hitting an allen key with a hammer to loosen it but to no avail. The bike was bought second-hand so I don't have an option to have a dealer or brompton fix that.
It's a standard job that you can pay a dealer to do. It doesn't matter that the bike is second hand, because it's not a warranty job. However, see my recent post in this thread - at least one source suggests heating to loosen the grip of the Loctite. Otherwise, you drill the bolt out with the drill bit that comes with the replacement bush kit. Various walk-throughs linked here.
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One day they'll wake up, smell the coffee, and use some sort of cartridge needle bearing.
I've wondered that. There must be a reason why this is the chosen design, but it seems pretty obvious that replacement will be needed and it doesn't seem designed to be replaced, if so many bolts have to be drilled out.
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Brompton use a particularly psychotic grade of Loctite, I think. The actual torque specified for the hinge bolts is pretty low. I fitted mine with normal nutlock, torqued them as specified, and they've never come loose. I got the shop to fit the bushes but said I wanted to fit the rear triangle myself, mainly so I could guarantee some grease went in there.
Drilling them out requires a few spare HSS bits (6.5mm), a lot of pressure, and low revs. You want to try and avoid heating up the bolt, which can make it even harder. An "egg whisk" hand drill works well if you put all your weight on it and turn the chuck rather than using the crank handle.
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I've been giving the problem of stuck hinge pins some thought and think I've come up with two ways to solve the problem. The first will get out the current fitment, and the second won't just prevent it being an issue in future but will also improve the maintenance...
1: Make a locking bolt up put into the end that comes undone first.... This is a bolt that is drilled down the middle into which a small screw is screwed down, wedging the screw in place.
2: Drill and tap the pivot tube on the outside to take a grease nipple and cross-drill your pivot hinges in future. To remove all you need to do is unscrew the grease nipple adn put a small tommy bar through the hinge-pin to lock it into place.... They could do this at the factory, it would cost pennies, but make it a lot easier to service in future....
chrisc
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#2 on your list is a certainty for my Brommies. Steve Parry has done that sort of thing for many years.
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So is the problem less that the bolts get irredeemably stuck, than that one bolt shifts and then the other spins with the spindle? In that case, this method (https://www.youtube.com/watch?v=8L2SXHDLffM) would make a lot of sense. Maybe that's what chriscross1966 is describing, though it's a nut on a bolt and I'm not sure what the drilling down the middle is for.
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So is the problem less that the bolts get irredeemably stuck, than that one bolt shifts and then the other spins with the spindle? In that case, this method (https://www.youtube.com/watch?v=8L2SXHDLffM) would make a lot of sense. Maybe that's what chriscross1966 is describing, though it's a nut on a bolt and I'm not sure what the drilling down the middle is for.
I was going to fit a grease nipple but there isn't a very obvious place to do so. It's all tight curves or welds around that tube.
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JE James have an interesting take (http://www.jejamescycles.com/brompton-rear-hinge-bush-x-5.html) (scroll down) that, as an alternative to drilling out bolts, you can cut away the nylon washers and use the resulting space to cut through the spindle.
I'm beginning to use this thread as a place to store all useful links on this :)
Should be looking at the Brompton I mentioned this afternoon - first investigation of whether the bolts will move.
Edit: average score, from what I can gather. One moved, one rounded.
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JE James have an interesting take (http://www.jejamescycles.com/brompton-rear-hinge-bush-x-5.html) (scroll down) that, as an alternative to drilling out bolts, you can cut away the nylon washers and use the resulting space to cut through the spindle.
I finally serviced my brompton rear hinge today. I delayed it by around 2 years... the waggle in the rear didn't really worsen much over that time until a week or two ago, when I decided it was too risky to leave it any longer.
One of the bolts was stuck firm so I set about drilling it. I'd bought a couple of drill bits to use besides the one that comes with the Brompton hinge kit and I figured that'd see me through the process. But I should've researched how to sharped drill bits... I hadn't realized that would be necessary; it's not something I've done before. After about an hour of drilling and having gotten about halfway through I figured I'd try the process mentioned above. It didn't seem particularly easy to cut the washer with a knife so I used an oscillating tool, and also cut some way into the spindle. But in no time the oscillating tool blade was completely blunted and I tried a hacksaw instead. It looked to me as though I was managing to avoid contact with the frame but once I'd cut all the way through (it didn't take very long) it was clear that I'd damaged the frame to some degree... and I don't think this was particularly avoidable using this method. But I think it's really just the powdercoat, and most of what was damaged is on the inside of the hinge, i.e. not visible.
I did the reaming with a standard hand reamer thing... it didn't strike me that this was significantly inferior to using the special brompton reamer. Perhaps using the Brompton reamer would give a result with slightly greater longevity, the tolerances being fractionally tighter. But the end result that I've achieved appears to be waggle free and good enough.
I used loctite 243; I hope this is adequate. I really don't want to have to be drilling bolts again, it's a ludicrous thing to have to do. A staggering shit design. So fingers crossed the medium strength threadlocker will be adequate.
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I used standard nutlock and, hundreds of miles of rough roads later, no movement. Just as well, because the RH one would be a tad tricky to retighten on a ride (unless you have a happy accident of chainring size and/or chainring cutouts).
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Just a note to say I managed to get a rusty, mistreated (not by me) for several years and at least 8 years installed without lube pivot out of an early-ish Mk4 frame wihtout sawing or drilling last night...
Having got the first screw out (2 decent long-arm 4mm allen keys required) i used an M6x50 allen cap-head bolt with a spring washer and a nut. The bolt doesn't need to be in hard, but the nut needs to be down as tight as you can get it. I reckon it's quicker than the other methods, doesn't involve power tools (can be an issue for some folks) and more importantly, won't scratch up the inside of your rear triangle... Found the basic technique on youtube (you'll have to google it, I haven't got a link to hand). The guy in it was using a plain washer, I found that wasn't as effective as a spring.
chrisc
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That will lock up the side where you've removed the bolt. However, the issue is shifting the other bolt. When I tried, we rounded the Allen key. Next up, on advice from LWaB, is heating to weaken the Loctite. Or am I misunderstanding you?
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That will lock up the side where you've removed the bolt. However, the issue is shifting the other bolt. When I tried, we rounded the Allen key. Next up, on advice from LWaB, is heating to weaken the Loctite. Or am I misunderstanding you?
No that was what was achioeved. First get all the crap out of the allen recess in the countersunk bolt out with a pin or a very small allen key or similar small stiff poky thing. Then use a decent long-arm allen key and hammer the damn thing into the socket... I reckon if I can get the screws out of a pivot in that condition (and they had rusted a bit even though the whole thing is supposedly stainless) then it is possible anywhere... better be cos I need to get the aftermarket titanium set out of my highly modded H3R (now H11R) at the weekend, it's nearly brand new and I'm swapping the Kinetics triangle for a vostok.bike one.
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The 4mm would help too, as that's slightly over-sized of course. I'll look at that, maybe in combination with the heat.
Got to get on and do it in the next few weeks, but the owner and I have both been short of time. However, I was talking to LWaB at the weekend and have promised some action soon.
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... better be cos I need to get the aftermarket titanium set out of my highly modded H3R (now H11R) at the weekend, it's nearly brand new and I'm swapping the Kinetics triangle for a vostok.bike one.
You bought a titanium spindle? I was wondering about those, they only save 20 grams or so but cost about the same as a brompton rear hinge kit, so if titanium stands up to the abrasive forces adequately it might be worthwhile. Intuitively steel strikes me as a more suitable material but I don't really have a clue.
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... better be cos I need to get the aftermarket titanium set out of my highly modded H3R (now H11R) at the weekend, it's nearly brand new and I'm swapping the Kinetics triangle for a vostok.bike one.
You bought a titanium spindle? I was wondering about those, they only save 20 grams or so but cost about the same as a brompton rear hinge kit, so if titanium stands up to the abrasive forces adequately it might be worthwhile. Intuitively steel strikes me as a more suitable material but I don't really have a clue.
IN my case it was purely vanity really.... Henrietta's mods were initially started with the aim of making my idea of a practical Brompton (an H3R) better.... My first Brommie was a secondhand M3L (a not unusual way to start off I expect) and after a couple of years I had a list of what I wanted different, the C2W scheme opened at work and I bought an H3R with dynamo lighting and front luggage... a few bits and bobs got changed around over the next five years, but mostly just detail stuff, but then I was in a position to buy anew bike and tried to list what I wanted different and it said "Henrietta, with more gears and lighter would be nice..."... The more gears came courtesy of an 11-speed Alfine conversion currently in a Kinetics frame, hopefully the recently arrived vostok.bike titanium frame will be going inthis weekend.... the "lighter" just turned into flinging carbon and titanium components from the mini-velo Brompton modding scene in the far east at her.... the last bits of that should be going on this weekend too, and at that point the only Brompton bits left will be the main frame and the handlebar stem.... so the titanium pivot was just part of that... Most of her old bits are going onto an old T3/L3 short wheelbase frame along with an 8-speed sturmey hub running fairly low gears as a shopping and load-carrying (for the allotment) bike..... I seem to have acaught the bug for Bropmton modding so in the workshop atm there's also an early Mk4 frame that's being setup with full Campy groupset and Cinelli drops... ploughing through the technical issues with that ATM, but it will fold with those handlebars, mostly thanks to the Kuosac 25mm tyres, that will be a weekend racer to annoy the Bianchi tifosi with (it'll be painted in celeste)..... and I've just ordered a Nickel S1E that's getting a 5-speed hub and a mildly ridiculous 80T front chainring as a shiny sunny days commuter...
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Wow. Pics please!
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Wow. Pics please!
Yes! Pics!
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And I thought my red S-type was pimped :o
The black M-type, in comparison, has no weight-saving gizmos at all, and almost leaves ruts in the tarmac. It's fine for the completely flat mile to SO's place, because it lives by the front door and is the only bike I have without SPDs.
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And I thought my red S-type was pimped :o
The black M-type, in comparison, has no weight-saving gizmos at all, and almost leaves ruts in the tarmac. It's fine for the completely flat mile to SO's place, because it lives by the front door and is the only bike I have without SPDs.
My bold.
You need to keep up, Roger. ;D
Chriscross's Henrietta is well documented elsewhere throughout the interwebs.
I've reeled in the modification work I've been doing on my Brommie as it has ventured into the-finances-of-owning-an-ocean-going-racing-yacht territory.(And I don't have access to a lathe at the moment - actually, I do. I've just remembered we have a Colchester Student in the workshop at work - running on 3-phase that'll take your arm off if you don't treat it with respect).
After which, it still remains a relatively heavy bike.
If ever this was cry for Brompton to get up to speed with the 21st century, and get jiggy with upping their production techniques to be capable of dealing with (the difficulties of) titanium, then this is it.
I reckon they're a company with sufficient clout / pedigree to raise the finance to R&D and put this into production.
If they were to do so, it'd put them way ahead of a game which they're already at the front of.
Alternatively, someone in the far-east will do so first.
Coming back to your post....
Not unlike yourself Roger, my Brommie is the only bike I have which I can get on and ride, without any adjustment to apparel.
On which basis alone, it continues to win, hands down.
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JE James have an interesting take (http://www.jejamescycles.com/brompton-rear-hinge-bush-x-5.html) (scroll down) that, as an alternative to drilling out bolts, you can cut away the nylon washers and use the resulting space to cut through the spindle.
The JE James method worked well :thumbsup:
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All done :thumbsup: :thumbsup: :thumbsup:
It's actually really easy once the bolts are out or (as above) the pivot has been cut. This afternoon, we removed the old bushes, cleaned out the tube, fitted new bushes, reamed them (a few turns on each side, nothing more) and re-assembled the bike.
I've gone at this really carefully and taken several sessions, not least because of wanting to get the bike apart before borrowing the tools or ordering spares. Also I had to go round to the owner's house each time and take the right tools. With everything to hand and a bit of focus, it should be a relatively straightforward job.
All working brilliantly, and many thanks to LWaB. I'll see about returning your tools.
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Glad to see that everything has ended well Mr D.
My mate in Oz will be checking this thread before doing a couple of Brommies out there.
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You need to keep up, Roger. ;D
Chriscross's Henrietta is well documented elsewhere throughout the interwebs.
I've seen it in the flesh, it's a spectacular thing!
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Well, that is a touch annoying. Trying to replace the extremely worn swingarm pivot on HK’s Ti Brompton resulted in the 5/32” Allen key (from B’s pivot kit) taking a set without loosening the bolt on one side. Trying the other side resulted in a larger set, also without loosening the bolt. One tool binned.
Wondering about the next step:
- Hacksawing through the bolts seems likely to damage the swingarm or frame.
- Drilling out both bolts meant a hell of a lot of drill sharpening the one time I needed to do it previously and I don’t have a bench grinder (or other grinder) here.
- Do I assume the metal is a little soft on this tool and try to break another Allen key? There was no sign of rounding out but I was leaning pretty hard on some extra leverage.
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Cheap Wilko drill bits. Hand drill (egg beater type). Put all your weight on it and turn the chuck directly. Use cutting fluid if you like.
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Used up every 1/4” drill bit in the house and just squeaked through both sides. Bushes removed, replaced and reamed, swingarm refitted, Loctite curing.
Ordered three cobalt drill bits for future use but will keep your tips in mind. Won’t bother with 5/32” Allen keys in future, just the Bondhus 4mm.
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Too late now, but when I borrowed your tool I successfully picked up a tip from the Internet. This argued for cutting away the nylon washers/bushes. This creates enough gap to put a hacksaw throught the pivot. Very easy.
See for example here (http://www.brompton.it/rivenditori/sp&192_files/ds-rhin_2.pdf), although I found the idea on a shop's site, illustrated with photographs.
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I though about that option but was a little dubious of avoiding accidental damage. I might have been happier doing it if only only one bolt wouldn’t loosen.
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Well, that is a touch annoying. Trying to replace the extremely worn swingarm pivot on HK’s Ti Brompton resulted in the 5/32” Allen key (from B’s pivot kit) taking a set without loosening the bolt on one side. Trying the other side resulted in a larger set, also without loosening the bolt. One tool binned.
Wondering about the next step:
- Hacksawing through the bolts seems likely to damage the swingarm or frame.
- Drilling out both bolts meant a hell of a lot of drill sharpening the one time I needed to do it previously and I don’t have a bench grinder (or other grinder) here.
- Do I assume the metal is a little soft on this tool and try to break another Allen key? There was no sign of rounding out but I was leaning pretty hard on some extra leverage.
Having had the 'fun' of doing this, have you got access to heat. The loctite set stuff they use on the bolt takes alot of heat to break have heated the allen key to get heat in to the bolt. Have also used a impact driver with sucess.
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The problem has already been solved this time round but an impact driver is probably the quickest option. Carefully applied heat would certainly work but I worry (probably unnecessarily) about nearby things.
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Hi guys, very pleased to join here and just to say hello and apologise for pulling up a slightly old topic but I wanted to join the forum as this is the most useful discussion on this particular subject that I have found.
After 45 years fiddling and fixing bikes I have just tackled my first Brompton hinge pin bush refurb and it did not go too badly.
To add in a few other points for others who might stumble across this excellent resource:
Like everyone else one bolt will come out fine, one will remain stuck. I really did not want to go anywhere near the pin with a drill so used the blowtorch on a sacrificial Allen key method to directly transfer the heat to the bolt and then half a dozen attempts with an M6 bolt and two locknuts (also a large penny washer and rubber washer against the rear frame - pictured) locking the other side as per YT video below. M6 is not exactly the correct thread but goes in and locks up fine. Took quite a few goes but eventually it will lock up the boltless side enough for the other side to free off.
I used an M10 tap to go into the old bushes but beware of going too far as the bushing depth areas are reamed out to around 11.75mm and the inner section of the rear frame pivot tube is narrower at around 10.75mm.
One thing that concerns me about the set up is that the SS pivot pin as others have noted sits against the inner face of the rear frame and will cause wear. I really don't know why Brompton don't refine this with a 'through axle' and cartridge bearings into the rear frame.
Where the pin meets the rear frame is also where the opposite of the countersink is deepest for the bolts so there is not much metal there.
I wondered about adding a thin form 'D' large 0.8mm SS washer to each side as a 'sacrificial' surface for the pin to sit against? See pic - any thoughts on this? good or bad! ;) Not sure there is enough tolerance to take the extra 0.8mm thickness each side though as I measure my pin at only 0.4mm less than the inside rear frame.
Rather than the factory super HD thread locker I'd much rather use a very light Loctite or none at all and check regularly for wear etc this way.
A very useful YT video here:
https://youtu.be/PZS_wtoNu8c?t=524
Also these links:
https://chestercycling.wordpress.com/2012/08/29/brompton-rear-frame-replacement/
https://www.perennialcycle.com/shopcast/replacing-brompton-rear-hinge/
http://www.shanecycles.com/brompton-hinge-repair/
Reviews/comments here: https://www.sjscycles.co.uk/consumables-brompton/brompton-rear-hinge-bush-kit-inc-spindle-tools-etc-workshop-use-only-note-on-ordering-comments/
https://www.brommieplus.com/portal_c1_cnt_page.php?owner_num=c1_343119&button_num=c1&folder_id=40985&cnt_id=862315&search_field=&search_word=&search_field2=&search_word2=&search_field3=&search_word3=&bool1=&bool2=&search_type=1&up_page=1
PICS:
(https://i.ibb.co/Yf3Wx8d/IMG-1193.jpg)
(https://i.ibb.co/DGhKPVM/IMG-1194.jpg)
(https://i.ibb.co/Pm8HGfN/IMG-1195.jpg)
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If the bolts are tight and threadlocked, the sleeve cannot move against the "ears", so doesn't wear them. It happens sometimes on Moultons with bronze bushes, where the sleeve seizes to the bushes and then the rear end rotates on the bolt, causing wear, but a Brompton sleeve is highly unlikely to seize in the plastic-faced bushes.
I just drill the heads off the old bolts with a cobalt drill.
An M10 tap will sometimes rip out with badly corroded bushes. The best option is a 7/16" tap, which is what Brompton used to supply when they would sell you a reamer.
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Thanks Roger, in hindsight the 'wear' on mine is I think just the paint and a maybe a fraction into the metal but only on the RH side which I think suggest it happened by being ground slightly against the pin when trying to lock it up with the lock bolt a few attempts - the LH turned back forth a few times before it finally gave way. ::-)
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Good post with all the links. But I think you should point out explicitly that your BrommiePlus link is to a reamer that is (a) available for sale and (b) cheaper than the official Brompton one.
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Coincidentally, I ordered one a few days ago.
I used a standard hand reamer, long enough to go through both sides, when I last did a Moulton F-frame. In theory the bushes on those should be just right when fitted, but they are all made by little cottage industry suppliers now, so mine were a little tight. It can be tricky to find one where the parallel section of the flutes is long enough.
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Good post with all the links. But I think you should point out explicitly that your BrommiePlus link is to a reamer that is (a) available for sale and (b) cheaper than the official Brompton one.
Ahh, if any rules have been broken I apologise - I'm happy with a basic adjustable reamer bought on eBay in the UK TBH - proceed with caution and it's reasonably easy and precise enough.
I'm still thinking of adding SS washers - getting anal nerdy here but I'm measuring the following on my Brompton:
Front frame width 68.40mm, + 2 x nylon washers (1.55mm thick) so total 71.50mm, pivot pin 71.80mm in length, 'OLD' rear frame 72.40mm so 0.6mm to play with.
So if adding 2 x 1mm SS washers (between pin end and rear frame) you'd only need to mill say 0.55mm off each end of the pin, use 1.0mm nylon washers and adding the 2 x 1.0mm SS washers it would be spot on with exactly the same 0.15mm excess each end of the pin and the fitment down to 0mm gap.
Errrrrrmmm...I think... ;D
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Not at all. I simply meant that you've found a more reasonably-priced, and available, reamer, which various people have been looking for. But that wasn't apparent until I followed your link out of curiosity to see to what you were linking. No broken rules that I know of, and anyway it's not my place to enforce any.
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If anyone is interested in following this I'll pop up some updates. As I say I might get the spindle and tolerances tidied up a bit but as the paint was a bit uneven anyway I carefully took off the main thickness with a soft aluminium edge and tidied up the traces with a rather Heath Robinson dare I say '400 grit facing tool' but more to give a nice clean surface to measure from. It's actually pretty blooming flat now with just a couple of thou' across the face. Just tighten up and turn the squares gently to clean things up.
(https://i.ibb.co/3hp5b9h/IMG-1207.jpg)
(https://i.ibb.co/gtLDDGZ/IMG-1208.jpg)
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The nylon washer performs three functions:
1. Allows for unevenness in the faces of the pivot tube and "ears"
2. Provides a thrust bearing
3 Improves sealing against water and dirt ingress
If you compare a Moulton rear end, they use flanged bushes to provide a thrust bearing but the length of the sleeve is ever-so-critical to give free movement without play, and the sealing is sufficiently bad that they provide a grease nipple. The Brompton design has its merits; it's just a pain to overhaul.
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Good points. I'm very tempted to not use Loctite at all and have it freely accessible for access to the rear end not just the 'bearing'. As you might have guessed ;D I'm an inveterate tinkerer/fiddler/checker/experimenter and pretty much check bolts etc habitually so torqued up right and checked often there is no concern.
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Bear in mind that the RH bolt is usually inaccessible if it comes loose during a ride. You sometimes get lucky with chainring cutouts.
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Bear in mind that the RH bolt is usually inaccessible if it comes loose during a ride. You sometimes get lucky with chainring cutouts.
Sure, TBH I have never carried a 5/32" Allen key anyway ;D but might start...
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I just came across this forum and thread as I am repairing a Brompton for a friend.
The main problem is a broken main frame hinge, completely broken across the hinge pin. I'm going to build it back up with silicon bronze or steel, using a TIG, but that's another story for another thread!
The reason for posting here is that I had to dismantle the rear hinge, which was worn anyway and about the only good thing I can say about it, as an engineer, is that it is lightweight!
I want to modify the hinge to make it easier to maintain (and use metric parts which are more commonly available...!!!).
Does anyone have the outer dimension of the bushes or ID of the tube they are inserted into?
The reamer dimensions are 9.5 to 9.55mm and the worn bushes on the bike I am fixing are close to 10mm inside diameter.
My idea, to make it easier to maintain, is to use stainless M6 countersunk cylinder nuts, which have an 8mm outer diameter and I'd put an M6 threaded rod between. I would make or buy close and machine bushes with 8mm inside diameter. I would get decent cylinder nuts, but I expect I'd need to polish them, to minimise bush wear.
I would clean up the tube ends as in one of the previous posts and use 8mm ID washers for endfloat. My gut feeling would be to use brass or oil filled bronze washers. The countersunk nuts would be locktited to the threaded rod (and maybe csk) and tightened to the point where the end float is taken out, but rotation is still good. One of the nuts could be permanently welded or brazed to the threaded rod, etc.
Top hat bushes could also be used, but I suspect the end wear would be way more than the bush wear, so it would be nice to make the washers separately replaceable.
This would then allow the rear hinge to be easily disassembled by removing one nut for regular greasing.
I've priced it up and parts cost is less than a Brompton hinge kit with bushes!!!
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If you add a grease nipple into the frame, bush wear stops.
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I don't like the need for a special reamer (which Brompton will no longer sell you, bur Brommieplus will) but it is surprisingly long-lived compared to the similar Oilite-bushed arrangement on a Moulton TSR. The glacier bushes have an incredibly high load capacity, it rarely corrodes because the nylon washers make a good dirt seal, and it retains grease well. It also benefits from the frequent folding action, which redistributes grease around the whole bearing. These pivots barely move when riding.
Overall it is better-engineered than Moulton's rear pivot (little changed since 1962), it's just not very home mechanic-friendly. Best left as designed. The bushes, bolts and washers are standard engineering parts and the sleeve/journal barely wears so can be re-used. The long piloted 3/8" reamer is the challenge.
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If you add a grease nipple into the frame, bush wear stops.
It's still a PIA to dismantle and replacements are still expensive from a small number of outlets. A grease nipple could be used on my proposed arrangement.
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I don't like the need for a special reamer (which Brompton will no longer sell you, bur Brommieplus will) but it is surprisingly long-lived compared to the similar Oilite-bushed arrangement on a Moulton TSR. The glacier bushes have an incredibly high load capacity, it rarely corrodes because the nylon washers make a good dirt seal, and it retains grease well. It also benefits from the frequent folding action, which redistributes grease around the whole bearing. These pivots barely move when riding.
Overall it is better-engineered than Moulton's rear pivot (little changed since 1962), it's just not very home mechanic-friendly. Best left as designed. The bushes, bolts and washers are standard engineering parts and the sleeve/journal barely wears so can be re-used. The long piloted 3/8" reamer is the challenge.
There are countless bikes with hinges for rear suspension and I have never come across one which was such a PIA to dismantle and would wear so much yet be so difficult to renovate. Generally wearable parts should be easy to replace. Many also use bushes, but they also have proper seals, so wear even less.
Ideally the bushes should be recessed so that seals could be fitted and then the endfloat washers, which will wear as they are soft, would only have to be endfloat washers.
I have owned many 1960s and 70s British cars and this has so many of their PIA to work on, or weird parts characteristics. They even had the mix of metric and imperial! I know many standard bike parts are still imperial, for historical interchangeability reasons, but why on earth do Brompton use imperial parts in some of the custom parts and not others?
Ease of dismantling for maintenance is my primary motivation for changing it. Secondarily the ease of obtaining parts.
Using metric csk cylinder nuts will make removal a 2 minute job.
(https://i.ibb.co/grmnRSW/Cylinder-Nut.jpg) (https://ibb.co/sgbBVK1)
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The stainless tube is 3/8" (exactly). The bushes are, from memory, 06DX06 which are 17/32" OD and nominally 3/8" ID, but will generally need reaming as they shrink when pressed in. The bolts are high tensile steel and 1/4" UNF 28tpi. There's nothing metric in the rear hinge.
Dismantling is a lot easier if you use the correct hex key bit - 5/32", NOT 4mm. It's also easier when doing it for a second time, as I suspect the factory uses a far stronger grade of threadlock than necessary. A 7/16" tap will drift out bushes easily, unless they have become corroded to the frame tube. I've only had to cut and collapse one set.
I don't think the countersinking is an anti-precession measure - it's just a way to fit the pivot arrangement into a very tight space at the back of the bike.
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The stainless tube is 3/8" (exactly). The bushes are, from memory, 06DX06 which are 17/32" OD and nominally 3/8" ID, but will generally need reaming as they shrink when pressed in. The bolts are high tensile steel and 1/4" UNF 28tpi. There's nothing metric in the rear hinge.
Dismantling is a lot easier if you use the correct hex key bit - 5/32", NOT 4mm. It's also easier when doing it for a second time, as I suspect the factory uses a far stronger grade of threadlock than necessary. A 7/16" tap will drift out bushes easily, unless they have become corroded to the frame tube. I've only had to cut and collapse one set.
I don't think the countersinking is an anti-precession measure - it's just a way to fit the pivot arrangement into a very tight space at the back of the bike.
Many thanks, those dimensions seem right, but the stainless part is not a tube, it's drilled and tapped either ends on the bike I have here.
I had no problems fitting bits into the hex heads using an Irish screwdriver (no malice towards the Irish intended). I could put way more torque than needed, but once one side was loose, unless you have an imperial bolt and nut to put into the loose side (all metric in Germany), it was almost impossible to lock the stainless rod sufficiently to put enough torque on the other bolt. A threaded hole in the centre of the frame tube would allow a bolt to be inserted to lock it, particularly if there were a flat on it in the middle. The same threaded hole could be used for a grease nipple.
I suspect most Brompton dealers use the same locking gunge. Note than many Loctite thread locking products are made to soften at specific temperatures. The red type is around 350C from memory, so a bit high. I have no idea which one Brompton use.
I agree that with the current design, the countersinking is needed to minimise protrusions. However it could have been better designed. I have an ultralight recumbent with 20" wheels made from some grade of high tensile aluminium (much thinner tubes than most aluminium bikes), all well under 10kg. The rear hinge for the suspension uses a much larger outer frame tube, about 25mm or so, with larger holes in the suspension arms and aluminium cups. A relatively standard bolt and nylock nut holds it together with the nut, bolt and bushes completely recessed and sealed. The larger diameter means much larger bearing surface to take loads. It seems like a much better arrangement and dead simple to take apart.
Off topic, but I wonder why there's never been an aluminium Brompton??? Titanium is so expensive and very specialised to weld but needed less redesign. I know aluminium would need a complete redesign and unless a high tensile grade was used, weight is not necessarily saved. However my lightweight recumbent is almost all aluminium and much larger than the Brompton, yet lower weight. OK, no hinges etc. to add weight. Due to back issues, I now prefer recumbents or more precisely semi recumbents and a 'bent which folded to the size of a Brompton would be nice.
I have an aluminium Dahon, which is much heavier than a Brompton, but it feels so much sturdier to ride. I have an ancient Bickerton, which feels like riding something made of chocolate (not ridden for decades), which is why I went for the sturdier but heavier Dahon.
The only problem with my proposed change I can foresee is the possibility of the csk cylinder nuts rotating in the rear frame. The standard design should clamp the stainless rod against one side of the rear frame or the other. Some Locktite should easily prevent that. There are csk screws with grooves to lock them, but That could cause wear, which would not be good.
FYI I have made my own bikes and trikes. My daily ride is the opposite end of the spectrum to the Brompton, a >50kg non electric, self built semi recumbent trike. The seat is a converted garden sun lounger and it can carry 2 crates of beer in the boot! It has over 20,000km on it mostly around town, although I've done some day rides over 60km. I weld and machine everything myself, so I know what I'm talking about, although it's not my day job. My current project is a carbon leaning trike for day touring.
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The hinges, which are normally very effective, have to be very hard, and tube diameters are limited by the need to fold, which is why they can't be aluminium. I suspect the titanium ones will also suffer recalls while they sort out teething troubles. The basic product hasn't changed much in 30 years, and Brompton have a bit of history in failed updates.
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The hinges, which are normally very effective, have to be very hard, and tube diameters are limited by the need to fold, which is why they can't be aluminium. I suspect the titanium ones will also suffer recalls while they sort out teething troubles. The basic product hasn't changed much in 30 years, and Brompton have a bit of history in failed updates.
The tubes can be made oval, which also has other advantages. There is a carbon fibre Brompton copy which uses oval tubes.
The frame hinge on my aluminium Dahon is a much nicer mechanism, using an adjustable over centre lock, similar to some old suitcase latches. No winding of nuts or bolts needed to lock in place and no hard metal mating surfaces needed.
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The hinges, which are normally very effective, have to be very hard, and tube diameters are limited by the need to fold, which is why they can't be aluminium. I suspect the titanium ones will also suffer recalls while they sort out teething troubles. The basic product hasn't changed much in 30 years, and Brompton have a bit of history in failed updates.
The T-Line has been thought about, but owner self maintenance appears never to be a Brompton consideration.
The main hinges on the T-Line use bushes (presumably because titanium would wear quicker than cast or forged steel) and the pin is a bolt with a nut on the end. Much nicer than the main hinges on the steel frames as it is easy to maintain and replace the bushes with no custom tools.
The rear hinge on the T Line seems to be identical to the steel frames, the parts are even interchangeable.
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My main concern would be cracking at the welds. Titanium is treacherous stuff unless you have the very best (or automated) TIG welding, with no overheating and absolutely no oxygen contamination. Brazing hi-tensile steel is child's play by comparison.
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My main concern would be cracking at the welds. Titanium is treacherous stuff unless you have the very best (or automated) TIG welding, with no overheating and absolutely no oxygen contamination. Brazing hi-tensile steel is child's play by comparison.
Yes, apart from the cost, that's why it's rarely used, except single piece cnc'd parts.
However the Brompton web site shows pictures of the titanium frames being welded and you can see the fittings to fill the tubes with argon while welding, etc.
The titanium is thicker than the steel frames (it only needs to be about 10% thicker, but it looks more). It's particularly noticeable on the main hinges, which look chunkier and because they use bushes, it looks like 8mm OD bushes, they need more metal around them.
The Ti frames do look much more professional, as they look more like moulded parts. The steel frames still look like pre 80s non waterformed / non welded (brazed with brackets) bikes.
Typical old British manufacturer under investing.
However I applaud them for not taking the easy route and move manufacturing to China.
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There must be a Chinese copy available somewhere.
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There are, in varying degrees of crapness and unsupportability. Some are better than others. The aluminium Merc was supposedly quite good, if you were lucky enough to get one where the seatpost didn't slip. The 3Sixty is the current clone of choice.
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There must be a Chinese copy available somewhere.
This one's not Chinese, Korean carbon fibre. Actually looks pretty good. Not a huge weight saving though.
http://chedech.com/?ckattempt=1
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I'm posting my hinge modification on another thread, because it's associated with the main hinge repair I've been doing.
https://yacf.co.uk/forum/index.php?topic=124758.25
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looking at replacing the rear triangle, as it is all rusty… bushes are fine, no play, so I was thinking a straightforward swap. Any thought on these replicas fron China? I can’t afford a shop replacement
https://www.aliexpress.com/item/1005005182570031.html?src=google&src=google&albch=shopping&acnt=548-301-0399&slnk=&plac=&mtctp=&albbt=Google_7_shopping&gclsrc=aw.ds&albagn=888888&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005005182570031&ds_e_product_merchant_id=670068893&ds_e_product_country=GB&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=20331137754&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gclid=CjwKCAiAibeuBhAAEiwAiXBoJAdSXfM6UGpb0Ydh41wnoyskrxdtArV0qORWoW3_JF9cjZMLV4HXwRoCtJAQAvD_BwE&aff_fcid=6133ea4abeb74c7e8e879e27157cac7c-1708018389211-03697-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=6133ea4abeb74c7e8e879e27157cac7c-1708018389211-03697-UneMJZVf&terminal_id=4ef24ec12a9544c5810a3ad130fd554c&afSmartRedirect=y
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It's probably from a 3Sixty or similar clone. The Brompton ones are no great shakes so I wouldn't worry too much about strength; whether it will actually fit properly is the question.
If you're going to the trouble of removing the twin bolts of hell, you will want to change the bushes.
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I looked at a video, it seems all I have to do is to undo a 5 mm Allen key, there should be no need to remove the bushes, use taps and all that stuff…
The rear frame is Aceoffix
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Good luck.
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I looked at a video, it seems all I have to do is to undo a 5 mm Allen key, there should be no need to remove the bushes, use taps and all that stuff…
The rear frame is Aceoffix
How-to videos are not to be trusted. You need a 5/32" allen key. Do not attempt to use a metric one (4mm seems right but isn't), as it will not fully engage and you may round the hex. The bolts are normally impossibly tight and I have always had to drill the heads off them. Once you've spent two hours getting it apart, it is very much worth having a Brompton dealer fit and ream new bushes.
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Well, some years after doing that friend's bike (see up-thread), it looks like it's time to do mine. Although I borrowed LWaB's reamer last time, I've since managed to obtain one. Wish me luck ;D
I did manage to replace the seat post sleeve, which was another reaming job. That's worked really well :thumbsup:
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Right, so not as simple... I suspect it is down to the heavy duty threadlock they use.
The toolset required to replace the bushes, as far as I can see is not worth investing in for a job that I will likely never do again. Equally, paying a shop to do the all job, including paying for an original rear frame is likely to cost several hundreds... so again, not worth it...
Alternative could be having a total respray/coat, but I would need to separate the rear triangle, so the same problem exists.
Sounds like the best course of action is to let it rot until it fails and at that point sell it on Ebay for parts or take it to the local recycling centre. It might well last another 5 years problem free. Could be double that, if I didn't use it in winter... but then I would be looking at 15-20 quid per week in bus fares... 250 pounds in public transport per winter, give or take.
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Where are you and is the issue removing the bushes, or the reaming, or both?
For the removal, see comments above on the size of Allen key and the hacksaw trick, which is what I'm planning to use for my second replacement job (but carefully!)
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The only real special tool is the reamer. My local Brompton dealer charges a minimal amount to fit and ream new bushes if you do the grim job of removing all the old stuff. The old bushes generally come out with a 7/16" tap (yes, more imperial tools*) and a drift from the other side.
*an M10 tap works most of the time but can just rip out. They are glacier bushes; an unholy laminate of bronze, steel and dimpled plastic, which is the actual bearing surface. An M10 tap only grips the soft plastic.
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Hmm. The screws actually both came out with an Allen key, albeit using a ratchet handle and not the toy that comes with the Brompton kit. But the bushes are stuck fast. The tap holds fine in the bush, but nothing moves when I hit the drift (I'm using the old spindle). I've seen advice elsewhere to consider cutting through them (carefully!) with a hacksaw blade, and then working round them knocking them free. Anyone tried GT85 or similar successfully?
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I tried all sorts before I cut them out. There is some kind of dissimilar metal corrosion going on.
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Thanks - saved me a lot of time looking for other methods, anyway! I'll give it a go at the weekend, when I can spend a little time. Obviously it was your post that I saw in the thread elsewhere (https://forum.cyclinguk.org/viewtopic.php?t=79561).
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It is not terribly easy. A razor file might be a better tool than a junior hacksaw blade. When you have made a slot (or two), carefully tap it inwards with something pointy and a mallet. It will let go eventually.
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I've ordered a handle for the blade (because, obviously, a normal junior hacksaw frame isn't going to work). Hoping that helps, but will consider a file if not.
I did wonder whether it's possible to drive the tap in too far, to the point that it engages in the tube beyond the bush, but I don't think that's the issue.
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I've never done this job so, by all means, confine me to the 'doesn't know what he's talking about' bin, but a jeweller's piercing saw, with a deep throat, could be the easiest solution here.
Were it me, I'd probably make two cuts, as close to 180° opposite each other as poss, then give it some hammer and drift.
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And I've never seen a jeweller's piercing saw ;D
The ones I've just Googled are hacksaw-like. The problem with that is that we're discussing cutting a small, circular bush that has been inserted into the end of a tube. So a "framed" saw isn't going to fit. I don't think feeding the blade through, putting the saw back together, and doing both bushes at once would work, because I believe it would foul the central part of the tube, which is not reamed as are the ends. But any suggestion that makes it easier is really welcome, and I'll happily report back!
Here's Shane Cycles discussing the issue (http://www.shanecycles.com/brompton-hinge-repair/), and one of their photos showing the problem area:
(http://farm4.staticflickr.com/3823/9300174841_94aee96ece_z.jpg)
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Ugh..USian grammar, "fit" rather than "fitted"
A custom drift only works when one bush is already out.
It's a crap design that lasts longer than it should based on the tiny bearing area, but at the cost of maintanability. It's easier to change the hinge on a Moulton TSR, although they don't last long.
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And I've never seen a jeweller's piercing saw ;D
As an aside, after discovering parallel action pliers, I can thoroughly recommend an hour spent down the learning-about-jewellers'-tools rabbit hole. Some of them are surprisingly useful.
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(https://www.dropbox.com/scl/fi/h0y4zuevgp63x8r20ohli/Brompton-bushes-small.jpg?rlkey=nisdx0o4re8g6xy3wevaiqsqb&raw=1)
New bush for comparison. Wasn't too bad actually. To get enough pressure on the hacksaw, I had to feed the blade along the tube and then reassemble it onto its handle. Then I sawed both bushes at once. I got through the thickness easily, as you'd expect, but then had to chisel the bits out with a screwdriver and the butt of my hand. One fell out when I wasn't looking, which confused me, in spite of being corroded in solid when I started. It seemed as though each bush had one patch of corrosion somewhere, and would shift once that was freed.
I put a thin film of copper grease on the outside of the new bushes. Hope that helps next time!
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Mine looked even uglier than that by the time they came out!
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Hmmm. Now I've got a constant rattle (https://yacf.co.uk/forum/index.php?topic=113845#msg_2879229). Any ideas? Probably better in that linked thread, unless you think it's the new hinges (I don't).
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Rattle is usually the rear hub. Squeak is usually the suspension block bolt.
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What rattles in the hub? Not the 3-speed presumably, so the sprockets and Brompton-specific parts? It does sound rather like a badly-running chain except that, as I said, it happens when I'm not pedalling just as much as when I am.
Should the suspension bolt contact the seat bolt? Presumably not?
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Yes, the 3-speeds rattle, especially the BSR/SRF3 with its pawl actuator plate.
If it's chain rattle, check the chainline with a straight edge. The new hinge may have displaced the rear triangle slightly to one side. You can move spacer washers about to get the jockey wheels and sprocket in line.
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Not chain rattle I think because, as I said, it happens whether or not I'm pedalling.
I'll have to take another look at the weekend. Thanks for the advice. Would still appreciate comment on whether those two bolts should make contact, and/or photos of how they look on other people's bikes.
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For update see the other thread (https://yacf.co.uk/forum/index.php?topic=113845#msg_2879229) (definitely not hinge-related, so not so relevant here). Thanks to all contributors.