Bouncing bed.

[thz71]

If your gona do that make sure its nice and sturdy on the jackstands and the blocks are tight to the tires

sent from my outdated S3

 

[oohunter04oo]

Did it do this before the new tires?

 

[poncho62]

Are you saying that it is bouncing like the rear brakes are locking up?.....Is it like your ABS is coming on?

How are your front brakes and master cylinder?

 

[97DD]

Sorry didnt reply sooner. OT at work. front brakes are good. master cylinder was replaced by previous owner before i got the truck. the rear brakes dont lock up, the back end of the truck feels like its bouncing up and down if I brake at higher speeds to come to a stop. country roads out here are 45-50 in most places so thats the speeds i brake from. hopefully i get time this weekend to jack the back end up and take a look.

 

[Ruger_556]

You put new drums on it? Something isn't round if it's doing that. You check your wheel end bearings?

 

[97DD]

I didnt put new drums on, I had them resurfaced and put new shoes on.

 

[Ruger_556]

I didnt put new drums on, I had them resurfaced and put new shoes on.

Check your wheel end bearings then...

 

[97DD]

Will do. Thanks!!!

 

[great white]

Assuming it didnt do this before the rear brake work and given the "weirdness" of the described behavior in light or turned drums, new shoes and vibration braking above 50 mph, the only thing that comes to mind is oil on the shoes in one spot making them grab/chatter.

This could be a leaking axle seal or poor installation procedures. It could be a leaking wheel cylinder, but that would show up as a brake light on the dash eventually or at least a dropping master cylinder level.

If you did this job yourself and are no very experienced at it, it is possible you have two primary shoes on one side and two secondary shoes on the other. The other possibility is something is installed wrong or something has come adrift inside the drum. Installed wrong is hard to do in a spring/drum type brake system, but can be done with the right (wrong?) determination. Something adrift usually makes scrapping noises all the time.

The drum could also be turned too thin, causing it to warp from the heat. The shop should have measured them, but you never know.

Another thing that comes to mind is a hard spot on the drum surface. This can make it grab in one spot. This is pretty rare in a drum brake though...rotor is more likely to suffer this, a drum not so much but possible.

You could also have wrong "pads" on the backing plate where the shoes ride. If they are grooved from age/use and not letting the shoes move in and out smoothly you could be in a grabbing situation. They are also supposed to be lubricated with some high temp brake grease, but this is unlikely to be the sole cause of the behviour you describe.

One last suggestion is chuck a torque wrench on your lug nuts and make sure they haven't losssened off. Easy to miss if you have hub/lug caps or some sort.

EXTREMELY unlikely this is an abs fault since abs is inactive above 10mph, but you can pull the fault codes and check. The paperclip method works on obdII trucks for abs. Iirc, the pins are A and H in the data line connector and you watch the abs light in the dash for the flash out codes. Its extremely limited though as the abs module only holds 1 or two codes at a time.

Good luck.

Here's a little info on rear brakes and some issues, with pictures!

http://www.agcoauto.com/content/news/p2_articleid/187

 

[sewlow]

The paperclip method works on obdII trucks for abs. Iirc, the pins are A and H in the data line connector and you watch the abs light in the dash for the flash out codes. Its extremely limited though as the abs module only holds 1 or two codes at a time.

BJ, shouldn't that be for OBD1? Typo?

O.P., another thought on this. Has the box ever been off to your knowledge? Possible that those bolts are loose?