Horrible brakes vibration!

[turbokinetic]

When I apply the brakes on my 86 Century; there is a very rough vibration in the rear brakes. It is at 2x wheel speed. On any sort of wet road, the right-rear wheel will lock and slide at low speed. The car has conventional drum brakes on rear.
First I thought it was a wheel cylinder that had leaked brake fluid on the shoe pads, so I replaced the wheel cylinder and shoes. There was a SLIGHT seepage on the cylinder. The problem was fixed temporarily but gradually re-occured over about 5000 miles. This time all components were dry. I replaced both drums and the problem went away, temporarily.
Now, it is back again! About another 5000 miles have passed. I have isolated the rear brakes by capping the fluid lines to the rear and test-driving the car. With only the front brakes working, the car stops straight and vibration-free. With only the right-rear capped, the car pulls left and stops vibration free.
It looks like the drum on this right-rear brake is warped AGAIN. What could be causing this? The automatic slack adjuster is working on both rear brakes. The shoes have mostly full pad (afterall they ahve been changed so many times!!).
Why the right-rear, repeatedly? I've had this car 13 years and never had this before. I've got another set of drums to put on after Christmas celebration tomorrow.
Thanks,
David

[Zaloryan]

I have a similar problem, but my right rear brake doesn't vibrate violenty. It justs drags ever once in awhile.

[85_Ciera_Rebuild]

When I apply the brakes on my 86 Century; there is a very rough vibration in the rear brakes

Jack up that side...grab top and bottom side of tire, and push forward on top-side and backward on bottom-side...and repeat this in opposite direction...if there is extra free play, replace your wheel bearings...on both sides.

Compare to other side....

Spin wheel and listen...do you hear a dry bearing sound....if your bearings have not been replaced...chances are...

[turbokinetic]

Could very well be bearing. I hadn't thought about that! Car is 21 years old with unknown miles. I've never replaced the bearings. Will check tomorrow after our Christmas celebration.

[LordDurock]

while your at it check for a leaky wheel cyclinder (a its good pratice) if you find one i would replace both sides.

[BignastyGS]

Maybe a dumb thing,but if it has aluminum wheels especially, make sure the lug nuts are tight. My Grand Cherokee has 1 wheel that the lug nuts loosen after several miles after I have rotated them. Done it twice in less than 1000 miles. I thought someone was loosening them on purpose, but it will do it every time.

[turbokinetic]

Well, it was the drums. Thanks for the advice to check the bearings, they were fine on both sides though. Glad of that!
The right drum was awful. There were external heat marks on the drum in 2 positions 180° apart, as well as cracks visible on the friction surface.
The drum is highly oval, so bad it can be noticed with a ruler.
See pictures. I had to install another Chinese drum because this was so unsafe and I have to drive the car before I will be able to get some American-made ones. Thanks!
David

http://68.209.87.173/Temp/drum_1.jpg
http://68.209.87.173/Temp/drum_2.jpg

[Tonglebeak]

My right rear drum is definitely not round (damaged it while replacing a wheel stud), so all I get is a grinding noise when applying the brakes >_>

Can't wait until I got those damn brackets so I can go rear disc.

[turbokinetic]

Can't wait until I got those damn brackets so I can go rear disc.

Hey would you mind explaining your rear-disc conversion? I've thought about using the rear brakes from a 6000. However those are in such short supply I doubt I'll find one with all the pieces and parts still there.
Thanks,
David

[Tonglebeak]

mickstan, want to step in? LOL

6000 is what's needed, and I'm trying to get some mounting brackets.

http://www.cardomain.com/ride/805391/21

[turbokinetic]

Okay that looks awesome, Mickstan has done a great job documenting it. Hopefully will come across a suitable donor car.
David

[Tonglebeak]

IF you do, and happen to find another car perhaps...lemme know.

[86euro]

IF you do, and happen to find another car perhaps...lemme know.

Not to be a party-pooper, but there's a pretty fat chance of that happening. The one set I came across is the ONLY set I have came across. I've been keeping my eyes open for you though, and if I come across a complete car in the area for a reasonable price, I will buy it for that reason alone. Or just take mine back apart and have new ones made, if need be.

[Tonglebeak]

http://cgi.ebay.com/ebaymotors/Ponti...QQcmdZViewItem



Lol. I wouldn't want someone buying a whole car just for brackets though.

[86euro]

Just a little too far away