Vibration after rear brake job

[astronot]

Hi all,

Yesterday I replaced my rear drum brake shoes. I also replaced all of the springs and sprayed everything down good with brake cleaner. The drum didn't look too bad. I didn't have to do too much to get the drums off, just a few knocks with a mallet.

Today, I cannot drive over 55mph without experiencing extreme vibration. The vibration feels like an extreme unbalance somewhere, but I don't understand how something could have been affected that bad from the brake job I did.

Any ideas where to start troubleshooting?

Thanks!

[RonB]

Make sure you didn't overlook something simple, like getting your lugnuts tight. The brake job should not have affected the van this way.

[CD Smalley]

Did you happen to take the driveshaft out for any reason while doing the brake job? If you did it might be 180* out of phase.

[gptunah]

Originally Posted by astronot

Hi all,

Yesterday I replaced my rear drum brake shoes. I also replaced all of the springs and sprayed everything down good with brake cleaner. The drum didn't look too bad. I didn't have to do too much to get the drums off, just a few knocks with a mallet.

Today, I cannot drive over 55mph without experiencing extreme vibration. The vibration feels like an extreme unbalance somewhere, but I don't understand how something could have been affected that bad from the brake job I did.

Any ideas where to start troubleshooting?

Thanks!

It sounds to me like the drums may be overheating. Did you have the drums turned down before putting the new shoes in? If the new shoes are too tight, they will overheat the drums and cause them to warp and vibrate.

Another possibility may be that the drums are not seated squarely on the axle hub. When you put the drum and wheel back onto the van, did you tighten the lugnuts in a cross pattern, or tighten them in a circle? If you used the circle tightening sequence, try taking the wheel and drum back off and put them back tightening the lugs with a cross pattern. If you have a torque wrench, make sure they are all the same tightness.

[BluesCruiser]

also make sure ther is not anything between the break drum and the
axel a little rust particle could do it... lift the back and spinn the tire you may see it wobble.. stealbrush everything the break drum touches

[Three_Fingers]

You wouldn't happen to remember anything falling off one of those drums when you were whacking them with the mallet, would ya?
If you happened to knock a chunk out of one of them or if you knocked one of the balance weights off (Not usually easy to do), that'd cause an imbalance.

If the drum is out of round enough, it'll bind partway around and cause the sensation of an imbalance.

[mrbreeze]

I have had the same experience twice on two different Astros. I found that the backer plate had worn spots on them where the shoes seat against them. I removed the shoes and used a dremel tool to smoothe the spots and then lubricated the area where the shoes seat against the backer plate. This cured the problem. What happens is that the shoes don't retract fully after braking and drag against the drums causing the vibration. The last van that did that heated the new shoes so much they smoked like they would if you had driven with the emergency brake on.