Rogerzilla's £40 Sturmey-Archer ASC thread

[rogerzilla]

It lives!

[rogerzilla]

Modern S3X shell, needed drilling and tapping for an oiler (the cost of these little plastic oilers is horrendous because they're no longer made).  Spaced to 118mm (designed for 110mm) but that still leaves enough for full engagement of the axle nuts.  i used a torque wrench.



Very beaten-up 4 speed shifter hacked into an ASC shifter with a grinder and file.  Positions are "H", "N" and "L".  Cable tension in "L" is notoriously high because you're overcoming a lot of springs inside the hub.



1950s clubman racer, still quite capable of hanging on with a bunch of carbon bikes.  The frame is light (no-one knows what it's made from, but it's half a pound too light for 531) and it has fast tyres.



First impressions: shifts feel about the same as an S3X.  Far more efficient.  There is no perceptible drag in any gear.  It's conceptually an AW with an extra mechanism to allow the sun gear to slowly rotate in middle gear, which gives a closer ratio than you'd otherwise get by driving the gear ring and taking drive from the planet cage.  The S3X, on the other hand, uses a totally separate epicyclic for each of middle and low gears.  Slifghtly less backlash (free play) than the S3X.  Biggest ASC problem, apart from the narrow spacing, is the cable tension required to get low gear, which tends eventually to round off the shifter ratchet (so it's said).  The ratchet is reasonably easy to re-dress with a grindstone or file.

[rogerzilla]

First proper ride.  All the gears work. 

Did some very steep slopes (subway ramps, which are about 1 in 4) in low gear and it didn't slip, but I didn't have the nerve to get out of the saddle on a bike with a proper gonad-threatening top tube  .  No noise (the S3X is a bit of a coffee grinder in "1"). 

Shifter doesn't slip. 

Managed to induce hub slippage in low gear once, immediately after climbing a very steep ramp out of a subway, but only when leg-braking.  Suspect slight cable stretch, because I tightened it and it didn't do it again.

Overall, it's quite impressive but it needs a proper climbing test.  The idea is really that you leave the hub in direct drive except when you really need a lower gear to get up a hill, so it's important that the low gears don't slip under maximum load.

[Moultonaught]

Really enjoyed reading this thread.
I remember thinking what a lovely and eclectic bike on the Oxford to London ride I attended, now even more so.

[zigzag]

very interesting project and a lovely bike for the hub to be installed in. my favourite photo is:



so much metal for just two extra gears!

[clarion]

Lovely.

[Oaky]

very interesting project and a lovely bike for the hub to be installed in. my favourite photo is:



so much metal for just two extra gears!

That's made me curious - how much did the stuff in the tupperware box weigh?

[rogerzilla]

Tony Hadland's book doesn't give a weight for the ASC, but it feels a tad lighter than an FW (which is prodigiously heavy).  Almost the whole shell is full of case-hardened steel.

Did about 10 miles on it today with Miss Z, up and down some steep hills.  It slipped like buggery until I realised that the way to adjust it is simply to have no extra pull left at all on the toggle in bottom gear, which is the one that is hardest to lock in*.  This means the indicator rod is a mm or so inside the axle in middle gear, not flush with it.  ISTR one of the old CTC guys saying this was de rigeur for an AM as well, although IME the post-1950 AM is very unfussy (earlier ones are crap, slipping all the time in low gear, and Sturney-Archer redesigned the gear ring to cure it).

Anyway, once the cable was tight enough it worked flawlessly and it's extremely smooth and quiet.  I rather like it.  My oil sealing worked and it didn't lose a drop when hanging up over the last week - there are about 2 tsp in there, which is quite a lot of free oil.


*to engage low gear, the main clutch moves but it's already engaged fully with the gear ring in middle gear, so that's neither here nor there.  The important bit is that the "dog ring", a sort of secondary clutch, has to overcome the big low gear spring, unlock the primary sun from the secondary planet cage and lock it to the axle instead.  This takes a STRONG pull on the cable and there is a position between low and middle gear where the sun is not locked to anything and no drive can be transmitted (which means a gonad/top tube moment if you're honking uphill).

[rogerzilla]

OK, ASC cable adjustment 101.

Forget the indicator rod.

Cable adjustment is actually simple without it.  In high gear (direct drive), the cable should have zero slack such that the toggle chain should be at the point of moving out of the hub, but no further.  If the toggle is out of the hub at all, even 1mm, the clutch will not be fully engaged with the planet cage.

Now get it in bottom gear (the wheel and crank need to be turning so you can shift).  Pull the cable adjuster with your hand.  The toggle should not come any further out of the hub AT ALL.

Middle gear has to look after itself.

[clarion]

Remarkably similar to the procedure for an S3X IME.

[rogerzilla]

Yes, the orange band on the S3X toggle is very imprecise.

It seems very wrong to have a fixed hub that contains false neutrals, but I suppose (as there isn't a pawl in either the ASC or the S3X) there is no other way to avoid simultaneous engagement of two gears. 

The normal 3-speeds have freewheeling pawls which can be over-run (in all freewheeling 3-speeds the low gear planet cage pawls are overrun as soon as middle gear is engaged, and in the modern N.I.G hubs there is a head-scratching arrangement of shrouded two-way pawls in the driver  that also allows simultaneous engagement of middle and high gear without damage, although it also makes them unpleasant to ride as they are more prone to rattles and the pawls don't always catch first time when taking up drive - give me an older AW every time).

[rogerzilla]

The ASC has been pressed into commuting service this week.

Turned left into the last lane at the same time as another rider on a fancy road bike was turning right into the same lane (prat - should have given way).

I don't think he even got to eat my dust, I left him so far behind so quickly.  The clubman is a terrifically fast bike because it has very modern Vredestein Fortezza racing tyres.

[therealrendo]

This takes a STRONG pull on the cable and there is a position between low and middle gear where the sun is not locked to anything and no drive can be transmitted (which means a gonad/top tube moment if you're honking uphill).

Thanks for this, i guess this maybe similar to mine, and possibly the reason i think i only have two gears available. i've had the hub apart a few times to investigate, but it all looks there and in good condition.
Time to put it back in the frame and try again.

[Xc.Hamster]

Hi I also have a ASC hub and have needed some parts for it and found this website
http://www.oldbiketrader.co.uk/display_Sturmey_Archer.php?options=internalhubparts

[rogerzilla]

Yes, that's where I usually get stuff from.  Most of the consumables are available, like washers and bearings.