How easy is it to dismantle a Brompton for a re-finish?

[GrahamG]

I've got an old brompton that is getting decidedly rusty in places - to the extent that it really could do with a re-finish. I'm happy just using it until it dies but on the other hand, if I can give it a fresh powder coat, it'll probably outlive me with the amount of use it gets. Is it a royal PITA given the folding joints/parts?

[rogerzilla]

I did this two years ago.  Not too bad, until you come to the rear hinge.  Try a little heat and an allen key first, as you might get lucky.  The bolts probably won't budge, so you have to drill the heads off.  This took me two whole evenings.  Use a hand drill (eggbeater type) and lots of cheap 6.5mm HSS bits.  Turn the chuck, not the crank handle, with all your weight on the drill.  A bit of cutting oil may help.  Do not use any speed as this just heats and hardens the bolt even more.

Once the bolt head are off, the spindle comes out.  Now screw an M10 tap into one of the bushes, far enough to get a decent grip, then drift it out from the other side.  It will bring ther bush with it very neatly.  Repeat for the opposite side.

The seatpost bush can just be broken into bits and pulled out.  Clean away any residual glue.  Contrary to urban legend, a new bush is easy to fit with a spot of rubberised glue (don't bother with the special Brompton stuff) and does not need reaming in situ.  Actually, I think I have one kicking around if you'd like it, because they come in packs of two for no reason and they are both the same size.

You should leave the pins in the stem and main frame hinges; they don't need to be removed for enamelling, and if you do have them removed the hinges will need reaming for oversize pins - a factory job.  Argos just freed them up afterwards, and they do lots of Bromptons.

The headset cups need to be knocked out as per usual, as does the crown race.  You may find the lower cup is loose, as the head tube has become ovalised.  If this is the case you may be able to get the tube filled with a bit of braze and re-reamed to the correct ID.

The new rear bushes WILL need to be fitted and (usually) reamed by a Brompton dealer but this is cheap (I paid a tenner); the bit they hate is drilling out the old bolts.

Finally, check the rear triangle very carefully for corrosion.  They are not painted inside the tubes, which are open to the elements.  The powdercoat holds it all together until one day it just cracks, having become wafer-thin.  This is the time to buy a new rear triangle if your old one looks a bit iffy; don;t waste money painting the old one if in doubt.

[GrahamG]

Cheers, Roger - it's the rear triangle that does look decidedly iffy. I'll hold off until I can afford to get argos to do it then.

[rogerzilla]

Argos will also make sure they clean all the threads, of which there are many on a Brompton, and not all of standard sizes.  For instance, there's the M8 hinge clamp bolt threads and the external thread for the stem "nipple".  It's also advisable not to get too much paint in the holes where the rear hinge bushes sit, or the bushes won't go in properly.

I've just realised that post mentioned nipples, holes, bushes and the potential spoonerism "hinges" 

[nobby]

There is a lot of information, including reaming the bushes yourself with a single sided reamer, on the Brompton Yahoo group.
I stripped and rebuilt mine last year without ant great difficulty.