Why do my brakes chatter when backing up?

[belfert]

My front brakes chatter when braking while backing up.  The noise is pretty bad.  The brakes work just fine when braking in the forward direction with no noises?  Any ideas here?

[dbenck]

My shoe brakes do this if they sit and get rust on them. Driving foward and good brake applications clears it up.
David

[belfert]

I wonder why this would start happening now?  I believe it happens even after a trip of some miles.  I can't recall if it did it when I backed into my driveway after getting home from my 4,000 mile trip.

I think I'll take the bus out for some driving on city streets next weekend if it stays nice and see if it clears up after a number of stops.  It has hardly rained at all here since I got back from my trip so I don't see how they would rust too badly, but even my car brakes will sometimes squeal a bit after just sitting overnight.

[luvrbus]

Brake shoes develop a wear pattern in the forward braking a little rust and moisture just about all buses will chatter in reverse after setting for a couple of weeks, out of adjustment brakes the more the chatter, did not your Bendix instructor in Bendix class you were in not cover that ?

[chessie4905]

part of the shoe must be dragging on part of the uneven surface of drum. If they aren't touching the drum, they aren't going to chatter. Take drums off and check for uneven wear on drums and shoes and grease or oil on linings or drum surface. Maybe your brake system is different than most coaches?

[belfert]

Brake shoes develop a wear pattern in the forward braking a little rust and moisture just about all buses will chatter in reverse after setting for a couple of weeks, out of adjustment brakes the more the chatter, did not your Bendix instructor in Bendix class you were in not cover that ?

The Bendix instructor didn't cover much about wheel end stuff.  I don't recall anything about chatter, but I don't remember everything from class either.

As to Chessie4905's point, this happens only when actually using the brakes.  Dina uses a fairly standard Q brake system.  Pulling any drums will have to wait until the weather warms up.

[luvrbus]

All good bus brake shops will turn a new drum so the shoe will run inwards instead of outwards inside the drum (per Meritor/Rockwell and Webb) that will cause chatter after setting for long periods when backing up

 I would not worry about if you have had new drums installed in the last few years at a good shop


good luck

[wg4t50]

Good time to check and adjust slack adjusters ..
Dave

[hargreaves]

Our city buses squeel at times, sometimes unbearably loud. We have a spot in the yard where we back up at about 10 miles per hr. and jam on the brakes. They would chatter and howl and deposit all the dirt and grunge on the ground from the front suspension. We did this about 3 or 4 times and the chatter would go away and the squeeling in forward would be gone.  As Clifford says they build up a pattern on the shoes and also some glaze. this process removes it.    Cheers   Gerry

[gumpy]

one side on mine does it every time I back out of the driveway after sitting for several weeks. It's caused by a film rust on the drum surface, and potentially slightly out of adjustment. It clears up immediately when I run it forward and apply the brakes. Only happens when the bus has been sitting for long periods of time.

Check your adjustment and don't worry about it. Just apply more brake the first time you use them backing up after sitting for a long time.