1996 GMC Suburban 2500 Violent Wheel Shake Please Help.

[daxr]

For the left rear to be not braking currently, but braking enough to wear out the shoes at some other point - I'd say the wheel cylinder is most likely. When a cylinder starts to freeze up it will still apply, but it won't back off under spring tension - so your brakes drag on that wheel. When it fully seizes up, then the shoes won't apply at all.

 

Its easy to check - open the bleeder at that corner while someone presses the brake pedal. If fluid squirts out, then its all good up to the cylinder. With the drum off use a screwdriver or prybar to shift the top of the shoes from side to side. They bear on the wheel cylinder pistons, and if they won't budge then the cylinder is frozen.

[Airwolf2tv]

Dax:

 

Thanks for the suggestions, this is helpful.

 

My STS guys also suspected the wheel cylinders and replaced them both. Further examination reveals that the left rear drum is twice the temperature of the right side. So it seems like the left rear is inexplicably overheating.....and I guess that is resulting in braking stress on the left front after things get toasty!! It seems like anything can be rationalized!! Also, until that left rear really gets heated up after driving some distance (5-10 miles), the front left/right caliper and rotor temperatures are identical...so I think that rules out problems up front.

 

I saw another forum article about a guy (and dealers and shops) who could not resolve a hot left rear situation on same vehicle. His final root cause ended up being the random brake shoes which were installed or purchased from an auto-parts counter. Three shops later they determined the shoe compostion (or something) was causing them to overheat. Changed shoes and it fixed his problem instantly.

 

I'm ordering all new OEM springs and hardware for my drums....replace shoes with Delco or Raybestos...and see what happens!! I don't recall, but I may have put some PepBoys springs on there in the past. Broke my cardinal rule about "the right part for the right fit"!!