Brake chatter in reverse

[captain ron]

I have a herndous brake chatter when backing up. mostly noticed when wet or very cold. sounds like the front end is coming out from under me. I assume it's in the front. any help?

[gumpy]

Yeah, I get the same thing on the front brake when it's been parked for awhile and I start backing out of the driveway. Only happens once and then I don't hear it again until it's been sitting for awhile. I think it's caused by corrosion on the drum, which gets worn off quickly.

[Nick Badame Refrig/ACC]

Hi Ron & Craig,

I also get the same noise while backing up after sitting a few weeks.

And I have brand new breaks and drums......

Nick-

[NJT5047]

Yep.  Sounds familiar.  Mine has done this since I bought it.  All brakes are in like-new condition.  Park brake release (almost always) without issues.  Just does it when backing up after it has set for a while.  I don't think its rust as the bus stays inside where it's dry.  Just cold does it.  Once warmed up, no problem.   My noise comes from either the tags or drive axle.
I know of others also that have the same issue....doesn't seem to a solution, nor does it seem to be a problem worth persuing...assuming that your brake system is otherwise in good condition.
I was told by a truck guy that the secondary shoe would try to grab when in reverse due to the way the friciton material wears.   Sez not to worry, unless it starts doing it going forward when at operating temps.
Cheers, JR

[Beatenbo]

I don't claim to be a know i t all, but I've owned 10 buses and nearly all have done this. Your wheels turn in a forward motion that puts a wear pattern on the shoes and drrums and when you back up you are going against the grain so to say. Damp or cold weather does seem to effect it more.

[gumpy]

I think mine has done it since I put new brakes on and turned the drums. I know the equipment is good. It only occurs once after sitting for awhile, and it seems to only be on the right front. Since it doesn't do it when going forward, or after the initial backup, I've never worried about it. Sure gets my wife's attention, though.

[RJ]

Captain Ron -

I worked in the bus industry for 25 years, and nearly every bus I dealt with would chatter the front brakes somewhat in reverse, primarily when cold.

I agree with others' comments that it has something to do with the brake geometry.

FWIW. . .