Clean the rims with scotchbrite and rubbing alcohol, or ssimichrome- and take a file to the pads to remove glazing. That should help the squealing. I guess you can hunt around for the 'perfect' spare part for the centerpulls to make them perform better, but sometimes a simple cleaning works wonders......
Tom Martin Oakland CA Rainy season has (hopefully) ended- time to wipe down the winter commuter.
-----Original Message----- From: HM & SS Sachs [mailto:sachs@erols.com] Sent: Thursday, May 12, 2005 8:44 AM To: Jan Heine Cc: classicrendezvous@bikelist.org Subject: Re: [CR]mafac brake question
In response to my tongue-in-cheek harangue about Mafac brakes, Jan Heine
wrote:
> Jan - Mafac brakes: It is the pads that cause the chatter. The "cheap"
> plastic bushings actually wear less than the brass ones... (and even
> those take decades to develop play.) With different pads (Matthauser
> mtb ones work great), you will have a hard time to get brake squeal
> from a Mafac centerpull brake. And chatter like on many modern
> cantilevers is unheard of in centerpull brakes anyhow.
Harvey: On one level, Jan, you are absolutely right: chatter starts
when the pad alternately sticks and slips against the rim, so changing
pad, approach angle (toe-in) and such can certainly help. On the other
hand, it is also a system issue. The bearing pivot design and
clearances, the arm lengths, and the stiffness of the arms all would
seem to be important.For example, it is not unreasonable that the
plastic pivots would have damped oscillations better than the bronze
ones. Among other things, these interactions among parts will set the
frequency of the chatter. I'm not sure that I'd mind chatter that
shifted to ultrasonic by human standards.
> Jan: The one thing Mafac Racers lack is snob appeal. They are so
> common, and were spec'd on such cheap bikes, that it probably is
> embarrassing to some that they also were and are spec'd on the most
> expensive Alex Singer bikes. (And Rene Herse used the even cheaper
> Weinmanns!) On the other hand, almost any used bike store will be able
> to provide you with spares for a dollar or two! (To be honest, the
> chrome-plating on the Mafac steel hardware does rust more readily than
> that on Campagnolo brakes.)
Harvey: To snobbery I'd add fashion. My first great road bike, in 1963, came with Mafacs. I converted my next one, a Paramount, to Mafacs, because that was the "in" thing back then. Since then, I've come to prefer the Universal 61, but it is only a preference. The Universal has demonstrably less leverage (with its native lever) than the Mafac, so it has more of an On-Off feel than a progressive feel. I like that, but it is preference, not performance, and one of the things that keeps the list fun.
harvey sachs
mcLean va