Squealing Brakes

[RPGR90s]

Although I've owned my '74 R90s for almost 40 years now, (140k), I've never been able to solve or even reduce the amount of front brake squealing. I've tried the goop on the rear of the pads, checked the solid (oem discs) for warpage (there is none), different pads, clean the pads and rotors with brake cleaner, and even some very fine sandpaper, all to no avail.

I will see the squealing abate for about 20 miles or so, right after cleaning the pads and rotors, but it always comes back. What's really strange is even rolling the bike down the driveway, and if I tap the front brake, it squeals.

The pads are adjusted correctly and overall, the front brakes work excellent for a 40 year old bike and don't squeal when I grab a handful. It's just that initial pulling of the lever that seems to be causing the problem.

Would appreciate any insight.


Thanks,
RPGR90s

[Kurt in S.A.]

Can't say as I've had much in the way of squealing on my single ATE /7 front brake. I've always run OEM pads with the spring and o-ring on the back of the pad. I work to get the eccentric adjusted but that's seems to be more of an art than science...but I'm getting there. I'm generally not that aggressive of a rider.

You've probably read Snowbum's page on brakes. About the only thing he talks about for the ATEs is that if not occasionally used hard, the surface changes chemical composition that promotes the squeal from time to time. But you mention grabbing a handful so it would seem you're doing that.

Tom Cutter mentions something about those phenolic buttons that are used at the bottom of the caliper. He was discussing a "clunk" that a poster had but he said those buttons serve to both take up the space and reduce the cluck but also act as a damper to counteract squealing. Tom also has another "racer fix"...stay on the gas longer, use the brake harder!

So, say you do grab that handful...you get the initial squeak and then it's fine. Say you don't really use the brake for another 5 miles. Does the squeak come back that next time? All the time?

Kurt in S.A.

[RPGR90s]

good info Kurt. And thanks.

"You've probably read Snowbum's page on brakes. About the only thing he talks about for the ATEs is that if not occasionally used hard, the surface changes chemical composition that promotes the squeal from time to time. But you mention grabbing a handful so it would seem you're doing that. I've done a bunch of Track days on this bike so I tend to be a late, aggressive braker.

Tom Cutter mentions something about those phenolic buttons that are used at the bottom of the caliper. He was discussing a "clunk" that a poster had but he said those buttons serve to both take up the space and reduce the cluck but also act as a damper to counteract squealing. Tom also has another "racer fix"...stay on the gas longer, use the brake harder! I've had some issues with the buttons. The right side definitely has some play that I've been experimenting closing the gap with. Currently have both sides with about .003" clearance which should be close to stock.

So, say you do grab that handful...you get the initial squeak and then it's fine. Say you don't really use the brake for another 5 miles. Does the squeak come back that next time? All the time?"Not exactly. If I lightly grab the lever and keep the pressure consistent, it squeals. If I increase the pressure after the initial squealing, it goes completely silent

I used to have stock Ferodo pads but they almost never grabbed unless they were warmed up so I switched to EBC I believe, which do grab even when cold. Maybe the pad material is an issue with the old, OEM discs.

[RPGR90s]

Further answering your post Kurt,

So, say you do grab that handful...you get the initial squeak and then it's fine. Say you don't really use the brake for another 5 miles. Does the squeak come back that next time? All the time?If I brake aggressively, then it doesn't squeak. If I ride another five miles and brake hard again, the same level squealing is there. About the only thing I've found that temporarily eliminates the noise is cleaning the rotors with brake cleaner. Then ride a few miles with very reduced brake performance. About the time the brakes start biting again, the squeal returns.

[Kurt in S.A.]

I've never experimented with brake pads...always went to BMW for theirs. Maybe I don't know what I'm missing, but squealing is definitely one thing that I am missing!

Kurt in S.A.

[MikeL46]

I'm under the impression that the solid discs are more prone to squealing than the drilled discs are.

Mike

[Rob Frankham]

IIRC, the main reason for the move to pierced discs was that the solid discs squealed... try a pair of pierced rotors, see if it makes any difference...

Rob

[MikeL46]

The solid discs have braking issues in the rain. First application takes a bit to squeeze out the water and by then you've squeezed harder and BAM you have brakes. The drilled ones have a place for the water to go and work from the start. The issue seems more pronounced with BMW stainless brakes, not so much with cast iron brakes.

Mike

[barryh]

Besides improvement in wet braking the holes also improve dry braking by allowing the pads to "gas off"

I wonder if this gassing off can cause squealing on a solid disc. Perhaps not as the pads don't gas off until they get hot.

[gspd]

Brake squealing/squeaking is RARELY caused by the pad to disc contact.
It is almost always caused by the brake pad backing plate vibrating against the caliper.
If you remove your squealing pads and examine the pad back plate, especially the edges, you will see that some areas are shiny bare metal where they contact the caliper.
Solution: LIBERALLY coat all the surfaces of the brake pad back plate and the caliper areas that touch those edges with hi temp grease or anti-seize and the squealing will cease.

This works every time, be it a motorcycle or car.

Money back guarantee. ; )