cerami50

Before I spend any more time and money chasing a ghost, I want to make sure my next move is the right move, using your opinions and suggestions.

Symptom: Brakes pulse during braking, can feel slight rub while creeping forward. With RR wheel jacked up, wheel drags over same arc with every rotation. With wheel jacked up so it barely touches the ground but can still rotate, one spot shows drag over a larger tire patch than others.

Troubleshooting: Rebuilt rear drums including new shoes and drums. Had new drums turned. Replaced RR axle (due to perceived bend from 'touch' test above). Disconnected parking brake cable.

Next move - replace RR wheel cylinder. I think this became more obvious today when I had the drum torn apart again and noticed the forward plunger will move while the rear plunger seems to be bound solid.

Sound about right? If the wheel cylinder was only applying pressure to the forward shoe, could that explain a once-per-rev pulse (I would think it would be constant)?

THanks in advance.

ChippyDiese1

You may just need to space the shoes manually because your star thingy which is supposed to automatically space them is stuck. Those parts can get very rusty. Some PB, flat head screw driver and a hammer should get it loose again. Look up how to space drum brakes. The shoes should slightly touch the drum, space until tight then come one click back.

One way to test this would be to have a buddy watch the star thingy and pull on the e-brake (assuming you have it reconnected). If it doesnt move, then your brakes are not adjusting themselves outward as the shoes wear down. They should be checked/adjusted periodically. Also don't forget to bleed your brakes, that side might just have an air bubble. Replacing anything upside down, which may not be possible with shoes, I can't remember. But... if you put your calipers on upside down and the bleeder is at the bottom you will never be able to get the air out while bleeding, therefore you will never get a hard brake pedal (kind of unrelated but thought I would share from experience). Ask me how I know, spend like 2 hours bleeding my system before realizing.

Another thing to consider is your axle shaft, is the tire rotating true or does it have a wobble? I had an awful clunking noise coming from my disks after an 8.8 swap that was due to a bent axle shaft. Every rotation the caliper was being forced open then closing then being forced open again.

firehawk618

Since you replaced all the rear brake hardware and drum I am thinking your axle shaft may be slightly bent.

Check it out.

mentalbreakdown00

yes both pistons in wc should more free and with each other

cerami50

Thanks for the replies, guys. The star adjuster isn't causing the issue as it is brand new and I just adjusted it back to 'zero' and the issue still exists. Also, I replaced the RR axle shaft, and the issue persists at the same magnitude.

ehall

If it rubs one spot then something on the spinning half is out of round.

drum is deformed
drum slightly crooked
axle slightly bent
axle bearings damaged

Stuff that is mounted to the backing plate should not move around

cerami50

Maybe I didn't do a good job of explaining what I've done so far.

"drum is deformed" - issue existed with both old drums, brand new drum, and brand new drum after turning.
"drum slightly crooked" - see above
"axle slightly bent" - issue persisted after axle shaft swap
"axle bearings damaged" - one of the few remaining possibilities, though on visual check when I swapped the axle it looked and felt fine.

Nothing on the backing plate has moved as far as I can tell, though like I said, the rear-facing plunger of the wheel cylinder will not depress and presumably therefore will not travel outboard either.

mentalbreakdown00

I have experinced a few shoes in all my years from advanced and AZ, that were too thick causing me problems.... Maybe this is an issue?

firehawk618

Maybe the brake hardware "adjuster" they gave you is wrong.

It very well could be too long.

Did you compare it closely?

Turbo X_J

Perhaps you can provide a pic or diagram to make the issue a little more understandable.

cerami50

In the event another researcher stumbles onto this thread with a similar issue, I should probably post some closure. I replaced the discrepant rear wheel cylinder and the issue seems to have gone away. It has been two months now and I have not noticed any of the pulsing or rubbing sounds that I had before. With that being said, my brakes do seem to lock up prematurely lately, though that could be due to another brake element warping while I was fixated on this wheel or due to the rear leaf springs I have that are long overdue for replacement (weight balance). Cheers, and thanks for the help guys!

Turbo X_J

Are you sure the rear flexible hose isn't defective (collapsed)?

Bustedback

Replace both wheel cylinders. If one is defective it will cause some strange things to happen.

Fred/N0AZZ

I had no problem reading what you posted and you did everything correctly that I would started with, except maybe the axle.


I must agree with the last few posts about the wheel cyd's (both) and replace the brake lines. Can you see any where on the backing plate where there is, or has been a problem of any kind?

cerami50

You guys make a good point - for $8 a pop there's no reason I shouldn't have replaced both wheel cylinders and been done with it. The rear hard lines along the axle I replaced about 18 months/20k miles ago and don't see any sort of damage on the lines or at the backing plate. The flex line looks fine visually and I ran my fingers along the length squeezing it and there were no soft spots as far as I can tell. Once my roommate wakes up I'll ask him to stand on the brakes as I watch the line to see if it deforms, but it sounds to me like I should just be less lazy when changing wheel cylinders.