[CR]brake arm breakage / toe-in / breakage in general / request for a bolt

(Example: Racing:Beryl Burton)

From: <"tom.ward@juno.com">
Date: Mon, 29 Jan 2007 04:16:35 GMT
To: classicrendezvous@bikelist.org
Subject: [CR]brake arm breakage / toe-in / breakage in general / request for a bolt

Sean and colleagues, esteemed Mark B., Sheldon: I hope much of what I am about to write bears the fact that it may, inde ed, will, be a sort of repetition. There are many cautionary essays and so on regarding toe-in out there in net-land; for example: http://www.sheldonbrown.com/brandt/brake-squeal.html contains a nice pie ce by Jobst Brandt on Sheldon's site. It's about brakes in general, not specifically Universal or Mafac (or Altenburger).

What we're most concerned about is the brake pad contacting the rim--the point of contact--maybe let the brake arm take care of itself, and: sha pe the shoe. Bending--or trying to bend-- the brake arm is a less-direct way of addressing the issue or problem, namely, controlling where the p oint-of-cantact of pad to rim occurs. The operative idea seems to be tha t superior and less-destructive results may be obtained by slightly resh aping new brake pads with a bit of sandpaper (flat on the workbench surf ace, I should think) rather than attempting to cold-set out-of-productio n brake arms. Of course some alloys will be softer and some more brittle ; must we test them in the vice (or with the old adj. end wrench)? We wo uld be asking too much of ourselves to think we would always sense what we "can get away with". Okay, in the last few days we've heard of pounding (on headset cups), st ubborn torqueing, marks on the inside of hubs and their dustcaps. I remi nd you all, this stuff isn't being made anymore. It may pay you to slow down! Think about pressing rather than pounding, take paths of least res istance, get a touch Taoist about it, like Alan Watts' 'Watercourse Way' . Don't let the frantic joy of reaching the end of assembly induce a man ia that you'll regret later!

Certainly taking more care is valuable for the altruistic extension of c lassic bicycle culture out into the future, too. Somebody somewhere down the line is going to need these parts as badly as we do now. A better t echnique is, at this point, probably documented here in the archives, or elsewhere on the net, just a google away. People here are sharing their experience in part for this reason, that the preservation and use of th ese cycles and components can be conducted in an enlightened way, rather than just folklore-ically, or through the ravages (and expense) of tria l and error. Not that I haven't damaged a thread in my time. Here's hoping someone has half of a Universal 68 in their parts bin for Sean. Best Regards, Tom (new cancer survivor at 39; still recuperating) Ward New York City recently by way of Neutron Beam Therapy at UW, Seattle, WA (December into January).

P.S. If anyone has one of the two pivot bolts for a Universal mod. 61 ce ntrepull in their parts collection, suitable for cannibalization, I coul d use one for a front brake. One of the bolts on one of mine was replace d somewhere along the way (before I got it) with a bolt with slots for a Philips-head screwdriver; a little too funky looking for my (intended) purposes. Thanks!

Sean Flores had written::
>So my brake saga continues. Found a drop bolt for the rear (thanks Oti s).
>But today, as I was giving the front caliper a quick toe-in adjustment, the
>arm snapped. No more front brake. Argh. Sorta¹ new it was a bad idea going
>in, but my stubbornness prevailed. At any rate, I need either a front
>(longer) caliper right side arm or a front (longer reach) brake. I
>purchased a set from Raleighchopper on eBay, but he can take some time to
>ship. So if anyone has the part in the interim, PLEASE let me know.
>BTW, is this common for these brakes, should I worry about failure or w as it
>just the amount of torque I was using?
>Here are some pics:

http://www.assemblylinecollective.com/ebay/img/universal2.JPG

http://www.assemblylinecollective.com/ebay/img/universal1.JPG
>The arm measures about 75mm from the center or the center bolt to the b ottom
>of the arm (going straight down). Sorry, but the shorter of the two si mply
>won¹t reach for me.

Thanks all.

Sean Flores San Francisco, CA


>Sean Flores wrote:
>> as I was giving the front caliper a quick toe-in adjustment,
>> the arm snapped. [snip]
>>
>> BTW, is this common for these brakes, should I worry about
>> failure or was it just the amount of torque I was using?
>Universal arms are famous for snapping while being toed-in, to the
>extent that I tell people to never toe them in by bending, not even a
>little. Talking mostly about 61s and 68s here, I don't have enough
>experience with other models to say.
>Maybe they were cast rather than forged? I don't know the metallurgica l
>cause, but they are more brittle than most other brands of brakes in th e
>classic era.
>Never saw one snap from normal use though, they seem to be plenty tough
>enough for the strongest braking.
>Mark Bulgier
>Seattle WA USA