tucker442

After spending 35 years trying to beat the Flat Rate Clock I got a job in a school bus garage. We have a fleet of Big buses and 3500 Chevy Van buses, seems the newer vans, 2008 and up have premature rear brake wear. We've tried the Bendix heavy duty pads, changed calipers and hoses, always lube all the slides and still seems the Right Rear Inner Pad wears out more than the rest. Has anybody else had this same issue? We do bring in the buses for a 90 day inspection so catch it most of the time before it gets to the rotor but just seems to wear way to fast. Any help would be appreciated

canucklehead

Try bleeding the left side only.

tucker442

I don't think only bleeding one side would be a good idea with 22 kids on board, but thanks for the comment

canucklehead

? Huh? You don't bleed it with kids on board. You bleed in the shop, but you know that.
See if there is any air in the line to the left side. If there is it could cause right side wear. Shot in the dark, but you have an odd issue. Have you wrote to GM about it?

tucker442

I did contact the local dealer, matter of fact 2 of them, they have no updated parts or no notes from GM about the issue. I have talked to other bus garages that have the same chassis buses and one garage has said the same thing. The earlier rear disc brake buses don't have this issue just the latest design which I think started with 2008 or 2009 production. Our older van buses with rear drum brakes go almost 40 thousand miles before replacement these new design rear disc ones don't go 15K before an issue. By law I can't reduce the pressure to the rear brakes like using a reducer or something, were not allowed to change anything because of the liability involved. If it was my own I would change the brake bias to the rear wheels.

canucklehead

That is so odd. The rears don't do as much braking as the front. Is it possible that this wear is being caused by a dragging pad rather than extra braking force? Maybe there is a clearance problem and the inner pad is not retracting far enough and dragging on the disc. How to check or fix that? not too sure.

tucker442

I thought about the dragging pad also but we have 3 of the same design chassis doing the same thing. I did leave the bottom clip that holds the pad tight from rattling off the last time I did the brakes and it seems they are all wearing even now but still a lot faster wear than the fronts, personally I feel the brake bias is just not calibrated correctly, I think there is too much braking being done by the back brakes but like I said earlier because it is a bus that carries kids I'm not allowed to re engineer anything. Thanks to all for your thoughts and comments.

tucker442

Read in the IATN Forum today the same issue someone else is having with a 2009 van so I guess it's not just mine. At this point I am seriously thinking about leaving a bit of air in the line and check the stopping distance, if that's within specs maybe that would help. Just this past Friday 10-9-14 van came in with the brakes metal to metal, I got under the van to look and sure enough right rear inner pad again. Now time for another rotor, and pad replacement because we have refinished that rotor twice before. This is crazy and we keep buying them for replacements of the old vans going out of service that had rear drum brakes that lasted a very long time.

canucklehead

What is the design? Dual piston or single piston floating? If its floating is it not floating properly? What about a line restriction that does not allow the pressure to bleed back from the piston once the pedal is left off....that would cause prolonged drag....

tucker442

It's a floating caliper with pins that are lubed very well, 2 piston on the inside, when released on the lift it spins free right away, no dragging, it just has something to do with the design I guess.