The Stovebolt Site Forums The Shop Area Driveline Brake change on 56 3100

I have just recently changed all the hardware (shoes, wheel cylinders, etc.) for the 1st time on my '56 Chevy 3100. My question is on the rear brakes. When I reinstalled the drums after changing everything, the shoes drag pretty good against the drum. The adjusting screw has been backed all the way off and they still drag. I have not installed the new brake lines so there is pressure on the shoes.

Any advice before I move forward would be greatly appreciated.

Kent Butler
'56 Chevy 3100
Houston, TX

Did you have the drums turned?? they might be out of round..another possibility is the linings need to be trued on a grinder...any competent brake shop can do both of these for you...

yes, shoes probably need arcing - good fat new shoes in good drums will usually be "too thick", but if the adjusters are really backed off alla way, the shoes need to be shaped to the drum, then run in and adjusted after they wear a bit

Bill

From what I have heard, you do not want to get these old drums turned it will ruin them, but I don't remember why.

Kent,
You should probably do a sanity check on the installation before you go any further. Check to see that the shoes are seated correctly on all the contact points including the parking brake crossbar. Make sure the springs are holding the brake shoes all the way against the center post and into the cylinder.
You can't damage the drums by turning them, however the more times they are turned the more material is removed. There are limits on how much can be removed, usually .060.
Fred

It's been a while since I've been in one of those olds brake drums. BUT, also check the backing plate. If there are wear pads for the shoes to ride on and they have a ridge, the shoe might be catching on it and hanging up. Smoothing that ridge will fix that. Putting a dab of white lithium will help assure smooth operation.

To add to what Fred says about drums, turning will make sure you have a good / full and flat surface for shoe contact. Not turning your drums means that they will wear past the maximum diameter that they were designed for and you would never know! Then you will run into such problems as over heating drums and wheel cylinders being pushed past their design limits. Not pretty when a piston comes popping out of a wheel cylinder or caliper. Especially when you want to stop!

With rear brakes there is the possibilty of the emergency brake hardware causing a problem. I personally have not heard of new shoes being too thick.

Along the parking brake hang up possibility, the shoes could be mis-positioned on the equizer bar (the bar that's in between the shoes on the rear). The parking brake lever actuates against this bar to transfer the motion to the shoes. If they're mispositioned, it will make the brakes drag.
The only old drums that there really is any issue with machining is the old Buick aluminum drums. The steel inserts have a nasty habit of separating from the drum during the machining process. Your drums should be avle to be machined just fine, provided that they're within spec (11.060" max).
One more thing, most brake shops do not grind shoes anymore. With most modern cars and trucks using 4 wheel disk and the aftermarket manufacturing pre-fitted shoes, there's not much call fo it anymore. Plus there's the OSHA and EPA liabilities concerning the dust from the grinding operation. There's a possability that a shop that services over the road trucks that re-line the shoes themselves might still do it, though.

I also had the suspicion that it could have something to do with the parking brake. However the previous owner had cut the line or it broke on him and was never replaced. I have checked and checked again to make sure that everything was put back in the same way that it came off. However, I am going to check again.

I feel as if something is wrong since the wheel turned freely before changing the brakes. Also, the fact that the adjuster screw is all the way out and there is still alot of drag. If I tighten the adjuster screw even a few turns, the wheels lock up to where I can't turn them by hand.

Thanks for all of the feed back received so far.

Kent Butler
'56 Chevy 3100
Houston, TX

"all the way out"?
the adjuster should be all the way in to have slack shoes

have a shop manual? it shows all the details about the brakes and is really useful - putting things back "the way they came off" doesn't necessarily mean it's done right, especially if it wasn't workin perfectly to begin with

Bill

Well, I did the reality/sanity check. Took it all apart and put in all back together again. The right seemed alot better, but the left side still had the consistent strong rubbing.

Took the drums to the local parts store to be turned. And the proceeded to screw them up and dig big grooves in one of them (maybe 57_StepSide you are on to something). Well those have been ruined now. They gave me one new drum free, but I had to purchase the second one so that they would match.

Now, the new problem is that there is even less clearance and the new drums will not even fit over the new brake shoes.

Any advice would be greatly appreciated.

Kent

Have you made sure that the adjuster screw is all the way back in? Plus, the parking brake might be a little tight, too. Try adjusting it back as well. As far as the drums go, it had nothing to do with them being old, it was the guy who attempted to turn them being incopetent. If it dug grooves in them, either the bits were dull, they tried to take too much out in one pass (trying to get it done in a hurry), or the feed rate was too high (again, in to much of a hurry), or most likely a combination of the those. I would almost suspect that they either gave you the wrong part (unlikely, the drums are the same '51-'70), or more likely, el cheapo overseas cast drums. We run into that one regularly when the customer wants to do the job as cheap as possible. Have the drums mic'd. They should come out to a nominal size of 10.090" to 11".

Kent,
I'm not convinced that you still don't have a problem with the parking brake hardware. You stated previously that the PO had cut the parking brake cables. Go back and remove any parts that connect the brake shoes to the parking brake, the crossbar and the arm that connects to the shoe. This essentially makes the rears like the fronts. See if you can get the drums on, if so it means that whatever was left of the cable is probably stuck and forcing the the parking brake to engage.
Fred

Maybe you could try the following:
put the shoes on one side without the parking brake cross bar and hardware in place. You have to start somewhere with the process of elimination.