This is about to drive us crazy!! Replaced rear shoes and drums. Wagner shoes. Noticed on the inside of the old drum, it looked like the shoe had been " skipping along' the inside of the drum. This is only on the right side. After replacing the rear brakes, went on an unloaded test drive, brakes perfect, no vibration. Pulled horse trailer appx 4 hours, toward the end of the drive, thought I MIGHT be feeling the vibration again. Pulled trailer again yesterday, vibration bad as ever. They are not being overheated, I've got my elec brakes working overtime to compensate for the crappy truck brakes. This truck does have the HD brake option, hydro-boost. also have replaced rear shocks. Did have a vibration all the time, worse when braking, discovered it was two problems, rear shocks too stiff combined with e rated tires. New shocks make the ride much smoother, now just can't find the brake-related vibration!

 

Brake cylinders sticking maybe?

 

possibility. I was thinking of that on my way in the house a few minutes ago, If I just hit the brakes, I get the vibration, If I let off the pedal a bit then re-apply it is smoother. I work at a parts store, and I am concerned about the quality of any replacement parts, so I do my reseach here before I go to buy. I know some folks have talked about a brake cylinder upgrade, however I have seen posts where trucks with the hydro boost have not responded favourably, seem to remember a brake lock up issue??

 

Outer bearings worn out causing wobble?

 

That's the other thing that came to my mind.........

 

But would wheel bearings only act up when we hit the brakes? It did temporarily get better when we changed shoes/drums. And I could feel better braking on the first trial run, truck stopped like it should! I have been reading older posts on brake issues. My husband is an ase certified master tech, and he checked the wheel cylinders, and we were planning on replacing the other side soon. There was evidence on the inside of the right side drum that the shoes are not engaging smoothly, but " skipping" along the drum. So I do believe the problem is in the brake itself. After reading other posts, wondering about the proportioning valve, and should I do the GM wheel cylinder swap, might as well change them since they are cheap and easiest in the process of elimination.. Also mentions building an adjustable linkage...