Meritor Quadraulic Brakes Are Starting To Have Problems

[kraig]

Just something else to check!

I recently atttended a hydraulic brake training class taught by a Meritor Tech. He did give us a Bulletin TP- 10134 issued on 08-10 which is attached. There is a problem with the heads of the bridge bolts popping off. This is not a recall and it is something that does not have to replaced unless any one of the bolt heads have popped off. The bridge bolts are the 4 allen bolts on each caliber. All you would have do is visual inspection of the bolt heads. I would just call this part of your PM inspection. The fronts are easy to see and the backs, you would have to feel the bolt heads. In my opinion, I don't think this should be big problem for motor homes with low miles as compared to like school buses and commericial vehicles. I would just say to inspect it regularly and to replace the bolts right away if one bolt head breaks off, because if two break off the same side, then you have replace the caliper. The tech did say even though the bulletin says you must remove the caliper to replace the bolts, they can be replaced on the vehicle. The fronts could replaced on the vehicle, but not the rears.

[kraig]

Forgot the attachment

[takepride]

Is this year(s) specific?

[kraig]

The tech did not say anything about year specific. When he was talking about the problem he said it was with the Meritor four piston qaudraulic brake calipers, so I would assume the problem would apply to all of them. All he said about the heads popping of could be caused from corrosion. The picture I posted was of my 2007 and they have rust on the heads. I would say to be safe, these brakes should be visually inspected periodically.

[takepride]

Thanks! I will.

[EngineerMike]

My guess is that if the bolt heads popping off are a result of repeated heating/cooling (i.e. expanding/contracting) cycles over the life of the bolt & caliper, and this causes a fatigue issue. For a motorhome which has long-haul truck kinda miles per braking application, this won't be a problem. Likely short-haul truckers are seeing most of the issue.

Could also be an over torque issue, in which case it would be random. Might be a good place for ARP bolts in the 200,000 psi range if they have a head diameter/thread pitch match.

[VanDiemen23]

Sometimes this failure is caused by spec'ing a very high strength bolt that has a radius under the head, and then forgetting to chamfer the hole underneath or spec a radius washer. Tightening the bolt scores the radius and then fatigue failure finishes the job.