Cycologist

I finished up the adjustments on the brakes, MAFAC 2000 for an early, I believe 1972 PX10. I can't seem to stop the squeaking. Rims are Tubular Mavic's. The side rim does appear to have some brake debris and I purchased and installed the Kool Stop for MAFAC's but the squeak is no better and no less after the instal.

Any suggestions?

The squeak only happens on the power brake application not when I'm feathering the brakes.

Thanks

Salamandrine 

Sand the rims. Use black koolstop pads, not salmon. Unless you live in Seattle.

tiredhands 

I had to do a pretty significant amount of toe-in to get rid of the squeal on my Racers. Now that the squeal is gone, the brakes are marvelous!

markk900

+1 - toe-in seems to be the best approach.

nlerner

greg3rd48 

Once toed-in the squealing mostly ceased and boy can those brakes stop on a dime with Koolstop salmons.

fietsbob

TRP adjust in place smooth post pads work well on Mafac

and many other cantilever brakes, using that mounting style..

63rickert

Period correct sound effects don't hurt anything. Mine always sound off when it's very humid. Could probably eliminate that too but It's a good thing to hear now and then.

Cycologist

Ok, thats what I was contemplating. I'll start with a Brillo Pad and see if that does the trick.

catgita

If the bushings are getting loose, I believe the Compass rebuild kit would make them better than new.
Compass rebuild kit for centerpull brakes

jj1091

I think the brakes are just screaming at the Suntour Spirt front derailleur, "Get offa here, we're a French bike."

Yes, the braking surfaces on those rims are in terrible shape, they need to be properly sanded, not rubbed with a Brillo Pad. If you can't get them smooth, they'll never stop well. Take your time and do it right, it's a nice PX-10.

Salamandrine 

Yeah, brillo pad might help a bit, but probably won't be enough. 220 grit is about right. Don't worry it's not going to sand the rim away. One easy way to do this is to put the bike in a stand, and then spin the wheel while holding a piece of sandpaper against the rim. Be careful not to sand the tires, obviously.

I'm assuming the brakes are properly adjusted and have a slight toe in already.

Fahrenheit531 

When I finally installed the set of Mafacs I'd been hanging onto forever they were consistently loud enough, both front and rear, that the equipped bike got nicknamed "The Banshee." I swapped out the KoolStop pads for some nondescript cantilever pads from the LBS. Stopping power reduced but still more than enough, and the howl was gone. And it was a howl, I dunno what all this talk of a "squeak" or a "squeal" is about.

I've gotta admit though, I dug the way that the howl had a reverb effect when I let off the brakes. I don't know if the spokes continued to vibrate, or the brakes themselves, but it was pretty awesome. And horrible. Mostly horrible.

gugie 

Every LBS mechanic from BITD learned how to toe-in brake shoes. Do just enough to eliminate the squeeling. I run salmon pads on all of my centerpull and cantilever bikes.

dddd

I think that you hit the nail on the head here. The grippier the brake pad, the greater the tendency to squeal, and the greater the need for additional toe-in.

On certain brake setups, I sometimes adjust toe-in by removing the wheel and taking a Dremel with stone to the aft end of the brake pad's surface. This when I might otherwise have to fumble with difficult adjustments or bend arms that pivot on mere plastic bushings.
And when I do bend brake arms to effect toe-in, I try to brace the other end of the arm so as to reduce the peak torque being transmitted through the pivot. I did this just yesterday, moments before selling a flipper bike having DiaCompe centerpull calipers.

Salamandrine 

I agree with everything.

Yep, salmon pads need a little more toe in. I toe in all brakes regardless, except campy NR/SR (and the clones), which don't need it, at least not with campy pads. The OP should definitely toe in the brakes if they are not already. This is so basic to me I kind of assumed it was done. The black vs salmon argument is moot (for now!), as the provided pictures show the OP went with black.

I do the same thing to the rear of the pads when they get so worn they are flat to the rim again. Works well. I've done it with a dremel but a sanding block works too. That's a thing about toe in. When the pads get worn down, the toe in disappears, and you don't really want to keep bending the armswhenever this happens, for I think pretty obvious reasons. Besides the sand down the trailing edge trick, another way around this is is to use modern pads with toe in adjustment, or something like the Compass angled brake washer, or a DIY version of them.

IME it is always possible to get rid of the squeal in MAFAC brakes, but sometimes it takes persistence and a few tricks. I still think the culprit in this particular case is gummy dirty rims.

John E

... but can a pushrod Simplex handle a triple with a 16-tooth drop from high to low? I am a big fan of single bolt circle triples such as used here. My fave was 48-45-34 on a 110mm BCD spider on my Peugeot. Since it was a 1980 model with a modern trapezoid / swing-arm front derailleur, I didn't need no stinkin' SunTour.

That is indeed a VERY nice PX-10!

Cycologist

With the first Simplex front derailleur I wasn't able to shift from the high gear to the low gear. So, Im messing around with the configurations. I know the SunTour installation gave me some consternation, so I installed it at night when no one was looking.

Cycologist

As far as toe in. I don't have much toe in. I can't seem to get the proper adjustments. When I tighten the bolts the pads shift ever so slightly.

How do you properly adjust for toe in. What step I'm I missing.

fietsbob

I bend the post relative to the pad holder, but, in use it usually bends back after a while..

Salamandrine 

You simply bend the caliper arms. That is the correct the old school method. Park made a tool to do it, but 9/10 times I used a small crescent wrench. You may need to move the pads down or the springs out of the way to get sufficient access to the arms. Generally you're looking for about a penny thickness or a bit less at the trailing edge of the pad.

To the customer this is to be referred to as "cold set".

Alternatively, you can file a notch in the washer ring on MAFAC brakes.

I strongly recommend you don't bend the pad posts. It weakens them and it doesn't work.

This is a pretty good tutorial. It only mentions the old school method in passing, but there's a picture.

Cycologist

Thank you. I think that will solve it. I was thinking about using a small piece of inner tube on one side to adjust for the toe in.

John E

Try a ca. 1980 Simplex unit -- I **think** it's called an SJ. Anyway, it was OEM on my PKN-10 and handled my 48-45-34 triple quite nicely. When I gave the bike to my son and he wanted wider gearing, we switched to 52-45-34, pretty comparable to what you're doing, and it still works nicely.

Cycologist

Thank you.

I'm going to look for that SJ, and it will keep it all French!

vespajg

good find