At some time during the life of your Brompton you may get some wear on the main folding hinge. Getting this repaired at a bike shop or buying the special Brompton reamer (GBP 200) is an expensive business. Here’s the cheap way to do it .
Disclaimer : If you mess this up you could damage your frame which will cost even more money, and also may need to go to your bike shop and explain why you messed it up 🙂 Attempt this at your own peril!!
Step one : Read this useful page —>>> Brompton hinge repair and buy the hinge repair set
Step two : Remove the right hand crank/ chainring and rear wheel.
Step three : Removed the 2x hinge bolts and the rear frame.
These are both installed with loctite so tighten and loosen each bolt in turn several times to break the loctite. If this doesn’t work you’ll have to drill one or both of the bolts out.
Step four : Now it gets interesting. Removed the 2x copper bushes from the frame.
Probably the best way to remove the bushes is to use a 13/32″, 7/16” or M10 tap. You screw the tap into the bush then knock it out from the other side with a drift(in theory). I didn’t have a tap so used an M10 bolt, this didn’t have quite the grip I would of liked so only worked on one side. I used a new bush to measure how far I could screw the bolt in.
Now I was stuck and tried all sorts of other things mentioned online to remove the remaining bush all with little success. In the end I had to make a custom drift that fit exactly through the shaft from the other side of the frame then knocked it through (its a very close fit).
Step five : Install the new bushes.
I used a piece of M6 threaded steel, spacers and nuts to press the bushes into place.
Step six : Reamer the bushes to the correct diameter for the new hinge.
In theory you should use the special Brompton reamer for this but at GBP200 there are cheaper solutions. I get the impression that the official Brompton reamer is in fact a taper reamer which to me seems silly when they know the size of the hinge. You can buy or borrow a 3/8″ reamer which doesn’t do the job perfectly but good enough. Reamer the bushes until the hinge is a snug fit but moves.
Step seven : Grease and install the hinge (make sure no grease gets into the threads).
Step eight : Re-install rear frame and other bits using loctite on the threads. Then fall in love with your Brompton all over again 🙂
All makes perfect sense to me. Like you, as an engineer I see no sense in using a special tapered reamer for parallel sided bearings of known diameter. A straight reamer of the right diameter to give the required fit is the ideal surely. Given that Brompton know what diameter they make their pins they ought to be able to decide what size that is!
As for the price for their reamer, words fail.
It is NOT a tapered reamer; it is a custom-designed precision double-pilot spiral reamer that enables both parallelism and precision in the delicate / tricky task of cleanly reaming the metal bushings’ interior NYLON surfaces to the exact specs to ensure maximum trouble-free life to the bearing rebuild. While a very expensive tool indeed, it is justifiably so — once you have shopped around for prices from quality reamer manufacturers to duplicate its specific required design features (sadly, I have!). Nothing else does close to as good a job!
This is a job I will have to do on one of our Bromptons in the next year. Using a bolt, nuts and washers to press in the bushes into the frame is a neat idea.
I also see no reason to buy the Brompton reaming tool either. IIRC it is actually 9.5 mm reamer which is ever so slightly smaller than 3/8″. Both are standard sizes you can buy on the internet for a fraction of the cost of the Brompton reamer. I have heard of people using a 9.5 mm drill bit to ream the bushes.
I think I’ll just be using a drill next time too 🙂
Thanks very much for this post, this is gold!
I used an 8″ drill (didn’t have a 9″ and I didn’t like the idea of removing too much of the nylon), and just worked by pusing side-wise, a slow operation, but it allowed to make it nicely tightly fitting. I used a hammer to ~gently tap the rod in.
Good news, thanks for the feedback 😉
Hi, Where do you buy the hinge repair kit. Some places I’ve seen say they are only available to be fitted by an authorised Brompton dealer?
Sorry this was almost 10 years ago so I can’t remember.
Thanks for the tip. I did the same- all reassembled and works very well.
Trial and error to check on the fit of the spindle- i was keen not to take too much off the bush.
What a superb little tutorial! A real gem!
I just changed my bushes. Thanks this was invaluable.
Used some coach bolts from ebay about £2.50.
I used a tampered reamer from ebay £14.
Loctite was £9.50 from Amazon
Brompton bearing kit £20.
I had an old tap & die set from Aldi and I was able to use it to knock the bushes out.
I used a hacksaw to remove rod out, I wasn’t careful enough and slightly damaged the frame so people be careful!
I was quoted at least £50 from Evans cycles and they would only do it during the week.
Thanks to you I’ve done it and I have the tools and knowledge to do it again if required.
Thanks.
Great job. Happy to help 🙂
Perhaps the answer is to not use either a parallel or a tapered reamer, but to use an adjustable reamer to get exactly the right fit.
eBay has adjustable reamers in the right size for less than £10
That is true in principle, but all the low-cost adjustable reamers that I can find on eBay have flutes that look like they are too short, so capable of reaming only one side at a time. Is there a way of ensuring the correct alignment of the two sides using a short reamer, or doesn’t it matter too much?
The best tutorial I found on the net. I found a good one in French to extract the piece
https://www.youtube.com/watch?v=xG8MRY8whIs&index=63&list=PL7HvT0BWDXJEmjzNncCL6vW6dX2nhHE_g&t=0s
but nothing to finish the job. Thanks a lot
Hi Bob, Nice film even though I don’t understand a word of it. Pleased to found this post useful. 🙂
Hi.
I’m currently servicing 3 bromptons, 2 of which needed new hinge pins/bushes etc.
I found that using an “easy out” of the appropriate size an excellent way to remove the old bushes. Just thread the tapered easyout in and tap it, and the bush, out from the other side using a 9mm car door hinge punch. (Or anything of the right size really).
One of the four bushes I was removing resisted this method so I carefully drilled the bush ever so slightly so that I could get a bolt in there and, again, tapped it out from the other side.
Now, I was lucky enough to have access to the correct tool, but it isn’t mine. I had thought, before actually seeing it and hearing that it cost £200, (although try actually Buying one Anywhere 😉 ), that it would be a convoluted reamer/jig arrangement to hold it Just so etcetc. Not so, just a simple bar reamer with enough length to guide it through straight. Both bikes, 4 bushes, took about 3 minutes to do, so, I am wondering how brompton justify such a ludicrous price for something so simple.
In future, and initially on one of my own bikes as a test run, I shall be trying other tools to do the job. The drilling idea would work, but you’d need a steady hand and good “engineers’ feel”.
I feel that niche tools are often marketing ploys to make money and, very often, can be gotten around with comon sense and a little care. 🙂
Regards, Maz.
I apologize. I completely forgot to say what a fabulous initial post. 🙂
haha, thanks 🙂 And thanks for your input.
Great demo, Shane. This was the most helpful one I found. I’ve just successfully replaced the bushes in my Brompton, so I thought I’d share the experience. One of the Allen bolts came out ok, but I had to drill the other. That was probably the most time consuming thing, because I kept blunting drill bits. The one the Brompton supply is a standard HSS 6.5 mm bit, which I didn’t dare use in case I damaged the frame. I found a 6 mm bit worked ok – once at the correct depth, the bolt was so weak that it snapped off easily, and then I could remove the rear swinging arm and remove the spindle. Next time I’ll use a 6 mm cobalt bit !
I managed to pick up a 13/32 tap on ebay for about £12.00, and it took the old bushes out easily once I’d tapped them and knocked it out with a drift. I used your technique of a length of studding and nuts/washers to insert the new bushes, which is an excellent idea. There was no way I was going to buy the special Brompton reamer either, so I used a 9.5 mm straight reamer (arceurotrade.co.uk, £12.87 inc. delivery) slightly tapered at the end, to widen the bush internal diameter. It’s 1 thousandth of an inch smaller than 3/8 inch, of course, but the spindle was a good close fit afterwards. I was very careful to ream dead straight – best done at eye level, I think. Maybe the fact that it is a tiny bit smaller gives you a bit of leeway. Finally, I used loctite 243 on the new bolts – hopefully that will be strong enough to get them to stay put – I’ll be keeping a close eye on these for a while. The whole job cost about £50 because of the tool purchase, but that’s cheaper than getting an approved repair done, and next time it will only cost me for the bushes.
Brompton really do need to come up with a better bush arrangement than this – it shouldn’t be necessary to replace like a consumable item. Brake blocks and cables are fair enough, even rims at a pinch, but not for something that you have to rely on to stop the back end of the bike falling apart!
Thanks again,
Steve
Hi Steve, thanks for sharing your experience too. Totally agree this this solution by Brompton sucks, especially on a part of the bike so likely to develop wear.
Enjoy your now less wobbly back end 😉
Thanks for the excellent tutorial.
I used a heat gun to heat the bolts, then the supplied allen key (with a long adjustable spanner for extra leverage) to loosen the bolts.
I had to re-tighten the first side before loosening the second one (to “break” the bond.
The old rod simply slid out, as the joint was so worn.
The bushes were problematic – solved with a 3/8 tap off Amazon. These took a LOT of force to knock out with a large hammer.
New bushes were inserted using a front wheel skewer and some washers, to gradually lever the bushes into place.
Reaming was with a 9mm drill bit, working gradually on the nylon bush facing and regularly checking for fit of the rod.
All sorted!
Thanks for the feedback 😉
Hi folks – this is brilliant! Ive just found out I need to replace the hinge pin on my Brompton. Ive had a look on eBay & now getting a bit confused as to which pin I need to get ;0. my Brompton is a m3l 2015 model. Any idea which pin I should buy?
Many thanks!
Fran
Sorry, I’ve been out of the Brompton world for a while and didn’t even know there’s different pins available. Maybe contact Brompton or SJS cycles ?
Hiya, actually im not sure there are different pins… checked on eBay and a seller seems to have different markings; so assumed diff pins… sorry I might be confusing matters! this is the listing:
Main frame hinge Spindle 6mm(QHSPINMF-6.0),
Main frame hinge Spindle 6.35mm(QHSPINMF-6.35) LWB,
Main frame hinge Spindle 6.10mm(QHSPINMF-6.10),
Rear Hinge/Bush&Spindle kit (QRHBKIT)
thanks!
OK, a quick google of the part numbers makes the answer simple, and the clue is also in the naming. Check out this page for some images (HERE)
The “Main frame hinge spindle” is for the main frame folding point, this spindle has the splines/grooves.
In the article I changed the “REAR hinge”
Therefore if you plan to change the rear hinge spindle you’ll need the QRHBKIT
Have fun
Fantastic! thanks for clearing that up. many thanks – will set about preparations!
I believe from what i know of manufacturers they need keep their product safe, they make specialised tools at stupid price to detract non-skilled from possibly botching the job and product now not being safe..
The Cynic however reckons it’s just scam to reap in more money from the unfortunate
This link is to Brompton reamer £50 hmmm… >Click<
Good price point, Would almost be tempting to buy 🙂
Hi I did mine 2.5 years ago. The only thing I can add is I used a set of screw extractors. A small one, Jamed into the open shaft screw end to lock the spindle whilst extracting the second screw. A bigger one to remove the old nylon bushes. I also used a parallel 13/32 reamer. Whilst using a smaller drill bit at the other end of the shaft in an attempt to keep the reamer ‘Parrallel’. So far i have nearly got 4000 miles out of the bush. But its tapping well now and I guess needs replacing again. B.T.W I have been know to repair car engines, Salvaged two cat 3 write offs. So consider i have a reasonable amount of mechanical knowledge.
I love that it has been years since this was initially posted and people still come here to post their experiences and tips.
Thanks to everyone for great tips!