Clunking sound when braking

Have a '89 S10 Blazer 2WD. When braking on a smooth road (actually any road) there is load clunk sound from the rear passenger side. The clunk usually happens about midway through stopping and usually only
occurs once. Happens while driving straight ahead or turning.
I recently changed my rear drum brakes replacing the drums, shoes, return and hold down springs (problem was ocurring before I did this and continues after the brake job) and noticed that the passenger side wheel cyliner was loose, I could turn it closewise about 1/4". The driver side was tight and had no play. I assumed that the retaining clip that holds the cylinder to the backing plate was worn and since the wheel cylinder looked questionable I decided to replace it. After installing the new wheel cylinder and new retaining clip, it's still as loose as the old one was.
Is it normal for the wheel cylinder to have a little play or should it be tight? If it should be tight and considering I've already replaced the cylinder and retaining clip, what can I do to secure it?
Thanks, John
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On 23 Dec 2003 20:55:51 -0800, snipped-for-privacy@yahoo.com (John W.) wrote:

Have the same problem, and the solution is to get a new backing plate. I fabricated a shim from the old retaining clip (I just tore off the tangs), but the cylinder still moves a little. It's really not safe like that, but it'll do until I get some time to tear apart the axle.
. Vuarra
Quid quid latine dictum sit altum videtur. (That which is said in Latin sounds profound.)
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Check with your dealer. I believe that GM has a recall on this problem.
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If it turns out not to be a recall and you need to replace the backing plate there are after market backing plates that are made in 2 pieces so you don't have to pull the axle to do the job. I'm pretty sure I got mine from NAPA for my 79 Malibu.
The old plate is cut up so it can be removed and the new one simply bolts onto the axle flange and then bolts together. Actually, pulling the axle on these rear ends is not a big deal unless the lock bolt breaks that holds the center spider gear shaft. If you do decide to pull the axles I would change the axle seals on both sides as long as I had it apart as they are about $4 each.
-- Mike.................................................... "Opportunities are spawned from crisis"
(John W.)

Check with your dealer. I believe that GM has a recall on this problem.
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On Thu, 25 Dec 2003 23:55:46 -0500, Dave in Columbus

GM Canada said that this problem was completely resolved by 1985, and there was no recall notice for my car.
I went to a local shop where I ordered a set of 2-piece backing plates for $30 CDN each. These are much cheaper than a GM retailer quoted (~$200 CDN each). I'll be installing them this week, along with a rebuilt master cylinder - it appears my juryrigging came apart very quickly :(
. Vuarra
Quid quid latine dictum sit altum videtur. (That which is said in Latin sounds profound.)
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If the wheel cylinder moves, the shoes cock, and make a clunk. A moving wheel cylinder will ruin the brake tubing. Epoxy putty can be used to shim the cylinder. A better solution is the two piece backing plates, sold at many parts stores. I'd recommend replacing the parking brake cables, as removing / reinstalling the old ones is a challenge.
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Yea, and do something very quickly because that wheel cylinder is going to blow out any time now. You'll hear it when it goes. remember to pump the pedal so you will have pressure to the front disks.
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snipped-for-privacy@yahoo.com (John W.) wrote in message

Thanks to everyone that responded. I checked out the backing plate as suggested and there was nothing wrong with it. Compared it to a new one from NAPA and they were identical (i.e., wheel cylinder fit the same, loose). I also tried shimming the retaining ring to see if I could get a tighter fit, but no luck. I ended up getting two 10-32 self-tapping machine screws and drove one through each ear of the wheel cylinder, through the backing plate and into the steel ear that comes off the axle. Now the cylinder is solid (doesn't move) and clunking sound is gone.
Still not sure was causing all the free play, but sound is gone, and screwing the cylinder down is what GM should have done in the first place rather than using just a retaining clip.
John
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