Drum brakes keep binding

[DeVilliers]

Morning all,

I've been having an issue with the drum brakes binding. Even from just in and out the garage with the restoration process.
The rear drums would lock up so hard, that the car doesn't want to move forward, but it moves in reverse.

So, I think I may have found the problem, but I need confirmation.
Google led me to believe that the springs are swapped, left and right.

The picture below is what is currently looks like.
2022-07-28_07-04-00 by DeVilliers Buys, on Flickr

From searching, I realized two things.
1. There should be a short shoe at the front and a longer shoe at the back
2. The white spring should be on the back shoe, not the front shoe like mine is.
3. My repair manual has got an inverted picture, hence it's the wrong way round.

Would this account for the brakes binding? I believe so.

My proposed solution is
1. Swap the left and right spring kits, so that the assembly with the white spring moves to the back shoe.
2. Remove some material on two of the shoes to have a shorter one at the front.

Any input on this would be appreciated.

Thanks 

[81Blackbird]

I haven't had drum brakes in decades, but it seems that the longer shoe should be on the forward side of the axle being most of the energy needed to stop would be on that side.
Not sure of the rest.

[tinpusher]

Off my 74 Ta, I believe it’s still virgin.

[tinpusher]

There is a straight flat bar that is under the rear cylinder that attaches to each shoe …..not pictured. …I believe one end has a spring on it that pushes against the emergency brake lever.

[Wallington]

Brake drums rebuilt4 3_12 by Aus78Formula, on Flickr

These use the automatic ratcheting and self-adjusting park brake cable. Normally you hit the brakes in reverse and it tightens to a preset level. Sounds like it's possibly doing the same, possibly forwards also. The lower red spring, if turned the wrong way, can also get caught in the teeth of the sprocket and not adjust at all, and not be apparent until after fully assembled.

The longer brake shoe is the primary, so to the rear.

[Gene-73]

I just did my drum brakes recently on my '73. It is easy to mix things up. Below are a couple photos.

Can't tell from the OP's photo if it's showing the driver or passenger side. As mentioned already the short shoe goes in front and long shoe in back, although yours look like they are both long. Did you check the other side of the car to see if they installed two short shoes over there?

I would think that it's kind of hard to swap sides on the springs since they orient with the adjuster bracket and the parking brake cable defines where that goes.  Your adjuster bracket looks different than what I'm familiar with but not sure if these changed in later years.

You shouldn't have to remove material from any of the shoes (as mentioned). If all four of your shoes are the same, I would start to suspect that the wrong kit is installed. That could be the source of your problem.

[DeVilliers]

So I swapped the spring kits around. Left to Right and Right to left.

Now at least it looks like the pictures above.
The only thing that is missing from it is the spring on the park brake adjuster. (The light blue one in Ben's pic or the white one in Gene's pic)

How significant would this be?

[Wallington]

I think it locates it, the tension holds it in place, without the spring would fall out. Although possibly only with drum removed.

[Gene-73]

That lower spring on the adjuster actually goes on to a separate small pivot piece, not the adjuster bracket itself. That looks like it's missing also.
Below is the exploded assembly from the Pontiac Service Manual that might help. FYI, a new kit with springs, brackets, adjuster, etc. are very common and cost around $10 per side.

Also here is a YouTube video that I found extremely helpful in sorting through the assembly (even though he forgets to install one of the pieces).
https://www.youtube.com/watch?v=P8qMfFtj6Vo

[JJ 109]

Good opportunity to convert to disc

[Wallington]

Sorry, I'm talking about a different spring, and a different colour! I'd expect swapping to problematic rear discs is even more difficult than finding the right arrangement of a few drum brake springs!

[DeVilliers]

Strange days, very strange.

I'm thinking the problem is either a bleeding issue or the master.
The only spring missing is the override spring on the adjuster lever.

Over the weekend I put in new wheel cylinders, applied grease where required and re-assembled.
Same problem again.

Drums run free, until you bleed the brakes, then it's rock solid.
The moment you release one of the bleeder nipples, the system releases. Drum run free again. Apply brakes and release and stays stuck again.
So, I pulled off the drum to see what is happening. When you step on the brake pedal the cylinder pushes out and stays there, the shoes do not return to position.

Regarding the bleeding procedure.
I always start at the wheel furthest away from the master.
However, the Pontiac manual indicates to start with the wheel closest to the MS, being Left Front (LF), then RF, then move to the back, LR then RR. Is this correct?

[aussieta]

have you adjusted the power booster pushrod to master cylinder
https://www.google.com/search?q=adjust+power+booster+pushrod&rlz=1C1GIGM_enAU962AU962&oq=adjust+power+booster+pushrod&aqs=chrome..69i57j0i5i13i30j0i390l4.12914j0j15&sourceid=chrome&ie=UTF-8

[Wallington]

The adjusting screw at base with sprocket is also side specific. When new one is plated silver, the other gold, LH or RH threaded. Make sure they aren't on wrong sides or that along with the automatic park brake adjustment could see them tightening when hitting the brakes.

Yes, start at furthest point from MC, being the RH rear wheel with the longer line to rear junction. You can now pick up the threaded tools that replace the combination valve switch during bleeding, but this is really an extra, just in case. I never had a problem before without one.