Author Topic: Play in Brompton front caliper  (Read 1331 times)

Play in Brompton front caliper
« on: December 12, 2018, 01:34:17 pm »
After I upgraded my brake pads, as in the other thread, my brakes improved, but I noticed that the front didn't seem as strong compared to the rear as I expected. On looking further, I found that there is play in the "outer" or "front" arm; I can wiggle it around a bit on its pivot bolt. I can't tighten the bolt/nut that secures it, or at least not using any reasonable level of force. It's not coming loose or anything, clearly, and I don't think it's enough to be a safety issue, but I've never seen play like this in any decent dual-pivot caliper before. Is it normal?

The result seems to be that the arm moves a little before the pads grip the rim properly, which presumably accounts for the slightly-less-positive feel when I brake.

Obviously I could just replace it, but there wouldn't be much point if a new one would be similar. The bike is probably seven or eight years old, so not the latest caliper model. It's lightly-used, so wear is unlikely.

Gattopardo

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Re: Play in Brompton front caliper
« Reply #1 on: December 12, 2018, 02:07:12 pm »
Single or dual pivot?

Re: Play in Brompton front caliper
« Reply #2 on: December 12, 2018, 08:36:13 pm »
Sorry, dual - this one.

I'd forgotten that early models would have had single.

Re: Play in Brompton front caliper
« Reply #3 on: December 12, 2018, 10:09:22 pm »
I have this exact issue  on my front shimano BR-R451 caliper.   

Gattopardo

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Re: Play in Brompton front caliper
« Reply #4 on: December 12, 2018, 10:18:21 pm »
Sorry, dual - this one.

I'd forgotten that early models would have had single.

Has something worn?  As I don't thing that there should be play.

Re: Play in Brompton front caliper
« Reply #5 on: December 12, 2018, 10:27:57 pm »
That's what I'm trying to work out. I could order a new one, but it's a waste if the play I'm finding is normal. I'll try wobbling a few brakes on tomorrow's train into London, and see whether anyone punches me in the face ;D

Gattopardo

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Re: Play in Brompton front caliper
« Reply #6 on: December 12, 2018, 10:29:39 pm »
http://si.shimano.com/pdfs/ev/EV-BR-6500-1681A.pdf

Looks as if something is worn in the no1 nut and bolt.

Re: Play in Brompton front caliper
« Reply #7 on: December 12, 2018, 10:37:43 pm »
The back-most portion of the Brompton calliper is threaded, so to tighten the bolt that holds the front arm on you may need to first slack off the nyloc nut at the other end.

I have a brand new calliper of this type in front of me - it has no play in it. There's a plastic washer between the two halves that I suppose may wear.

That Shimano one looks to be quite a bit different in construction - the pivot bolt is reversed and the whole thing is flipped left-to-right.

Re: Play in Brompton front caliper
« Reply #8 on: December 12, 2018, 11:37:06 pm »
Thanks. I didn't think of slackening the nut off first. I agree that wear is possible but, as I said, this bike is lightly used. Well, OK, it's got a heavier rider now ;D

Useful to know there should definitely be no slack. I'll see what I can do with your suggestions. Otherwise, maybe it's a replacement.

Torslanda

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Re: Play in Brompton front caliper
« Reply #9 on: December 13, 2018, 10:10:24 am »
Some dual pivot calipers use a tiny grub screw to lock the pivot bolt in place.

Please check before giving it big licks with the hex keys...
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.