Drum Brake Grabbing

[66 Sat]

This should be a simple question for someone - I searched and found something recently on a similar situation this but can't find it now.

• The drum brake is grabbing on the passenger side rear - not much, but the wheel is warmer to touch than the other side and you can feel it when going very slowly.

• The car will still creep in Drive, but not as fast.
  
• The grabbing seems to come and go.
• I jacked the car up in the air and turned the rear wheels forward by hand - they turned about half a turn and locked up. I turned them backwards and they turned as many revolutions as as I wanted. Tried forward again and they locked up.
  
• I pulled the passenger rear wheel off and took the drum off - photos attached. Now they turned forward as much as I wanted with no lock up.
• I put the drum back on and they still turned freely - asked my son to push the brake while I turning. After he released the brakes the wheels were totally locked up turning them forwards. I turned them in reverse and they turned ok, and then if I tried to go forwards they turned fine. Repeated this a few times, same each time - locked in forward, reverse turns and also releases them.
• The shoes seem to have excessive wear on the lower quarter of the shoe - I assume this is where they are dragging. The cylinder also looks like it's leaking a little.
• Brakes were bled recently after I changed an axle seal on the other side - it's only started grabbing since then.

Any ideas what's going on?

 

[R413]

#1 make sure the parking brake is releasing the shoes 100%. It looks like the arm hooked to the shoe is pulled forward slightly. Both shoes at the top need to be contacting the center pin.
#2 fluid on the shoes will make them grab the drum and not let it rotate how it should.
#3 does the axle flange move up and down at all? is the axle shaft end play correct? If to loose the axle is not centered on the bearing and it will drag the brakes. Is that adjuster stop tab home made? Fine if it is but it Needs to hold the adjuster ring from turning. It’s probably OK or the other side would be off also.
#4 the bottom 1/3rd of the rear shoe has brake dust covering it. That Means it is not touching the drum like the rest of the shoe is. Why not?

 

[66 Sat]

Ok, so the parking brake doesn't get used much as it doesn't release fully, unless I get under the car and just tweak the bracket that divides the 2 cables - then it's fine. I save it for special occasions and usually use a block of wood in front of the tire instead (I know, I know, but it's on my list to fix). It seems ok - the arm will move when pushed against - I don't think it's pulling the shoe forward.
The cylinder is weeping slightly but the shoes are dry. I was going to try to get a rebuild kit tomorrow.
The axle is tight up and down with only a tiny amount of end play - I set it by hand. I don't know what it measures but it's very minor. The adjuster lock is homemade and temporary - there wasn't one on there when I went to set the end play so I knocked up something and will replace it with the proper one when I change the axle seals and bearings on this side (they aren't leaking but I've done one side so will do the other).
You're right about the brake dust - I thought it was extra wear on the bottom but I just put my finger on it and it's dust alright - I have no idea why it's not touching there on either shoe.

 

[R413]

OK the park brake needs to return all they way or it will cause you trouble and grabbing. There is a gap between the shoe and lever. Should not look like this. This is likely causing your problem right now.

the cylinder leaking is bad, fix it when you can. It will get the shoes wet even though you cannot see it. Spray them with brake cleaner and wiper with paper towelSeveral times.

It’s good the axle is tight up and down

the home made tab is fine to use as long and the adjuster won’t turn you can use it.

if the axle seal is not leaking then leave it alone.

the shoes are not touching 100% because the drum is a larger diameter than the shoe arc. This will wear in and they will reach full contact later.

 

[66 Sat]

Ok thanks for the help. I'm going to pull it all apart tomorrow and clean and lubricate everything and hopefully fix the cylinder too. I hate drum brakes, they are both simple and complicated at the same time somehow.

 

[Big Bad Dad]

You know about needing a small dab of hi temp grease on the spots where the brake shoes contact the backing plates so they can move freely?

 

[66Satellite47]

That's a lot of non-contact area on that shoe.

 

[vance.dykes]

ok you have the wrong adjuster for the brakes and spring and no lever that i saw. so how do you adjust your brakes even and keep them that way. i just went to napa to get wheel cylinder kits they were 15 bucks but a replacement part was 12 buck . go to my mopar .com and look at a factory service manual for reference.

back in the day we would ark the brake shoes to match the drums that is why there is no ware on the bottom it will ware in over time.

 

[MoparLeo]

I would suggest you upgrade to the self adjusters, minimal cost. Replace instead of trying to rebuild the wheel cylinders and use new, bonded linings. Replace all hardware. Really brakes are the most important system on any car. Better to have all new components and know that all the parts are matched and current. Make sure that your brake drums are still within usable specs. The size is cast/stamped on the outside of the drum. The service manual calls for no more than .060 oversize.. The drums dimensions should be matched as closely as possible. Example 1 drum 10.060 left side and new drum 10.000. on the right side. Not a good situation. One drum will grip harder than the other and will always be un equal in performance. Brake component and service manuals always recommend that you replace drums/ rotors in pairs. Just like have a worn tire on one side sand a new tire on the other side will not be prefered during hard cornering and braking. Brake systems corrode from the inside out. Brake fluid is hygroscopic meaning it absorbs water. Water lowers the effective boiling point of the fluid, meaning more chance to boil, evaporate during hard or repeated braking that heats up the fluid.; Also the moisture causes rust to form inside the lines and wheel cylinders, master cylinder eventually causing hydraulic failure. Thoroughly flush the entire system with a new, sealed container of high quality brake fluid. Should be replaced at the same schedule as coolant, 3 years. Here is just one of many videos that help with re assembling the brakes. Best to take pictures during disassembly anyway.

 

[66Satellite47]

With manual adjusters, which I prefer on my Satellite, you do need to check them periodically. I suspect the shoe is binding a bit on the backing plate, disassemble and wire brush clean contact points. I'd also replace the wheel cylinder for sure, it may not be retracting properly.

Edit: If you can find a brake shop that still does "shoe arching" to match the actual drum diameter, that really helps. The shoes don't usually "wear in" very fast, resulting in the lack of full contact of the shoe.

 

[66 Sat]

ok you have the wrong adjuster for the brakes and spring and no lever that i saw. .

They are correct - they just don't self adjust. They are the 11" drums, the set-up is as per the Police/Heavy Duty as shown in the FSM.

 

[khryslerkid]

I pulled the passenger rear wheel off and took the drum off - photos attached. Now they turned forward as much as I wanted with no lock up.

Drum is probably out of round and hangs up in that spot.

The cylinder also looks like it's leaking a little.

Pull the rubber boot back and check. If it's wet then rebuild or replace both cylinders. Might be why the one side is not returning. Corrosion inside goes hand and hand with a leaking cylinder. The corrosion won't let the cylinder return where it should.

Nothing wrong with your manual adjuster. Just have to check them periodically.

 

[66 Sat]

Drum is probably out of round and hangs up in that spot.



Pull the rubber boot back and check. If it's wet then rebuild or replace both cylinders. Might be why the one side is not returning. Corrosion inside goes hand and hand with a leaking cylinder. The corrosion won't let the cylinder return where it should.

Nothing wrong with your manual adjuster. Just have to check them periodically.

I thought about the drum being out last night, the way it turns and then locks when turning by hand, and also the feeling of grab/release when rolling down an incline in neutral - I'll get it checked. The other side is fine - I had the whole lot off a few weeks back when I did the axle seal. Everything was cleaned up, I lubricated the contact points and painted the outside of the backing plate and drum - the amount of dirt and dust all around that area was unbelievable. Now I'm sorting this issue I'll do the same to this side.

 

[66 Sat]

Well I've pulled it all apart and the wheel cylinder and seals are in good shape (I had them rebuilt by a local brake shop a few years ago). One of the pushrods had some dirt and corrosion on it though, and that might have caused it to hang up on the outer boot. Also one of the bases of the shoe retaining springs was missing, so the spring was sitting against the shoe - that might have caused some binding too. I'll clean it all up and see how I go.

 

[66 Sat]

Brakes are fixed! I noticed the cylinder boots had splits in them so replaced them along with new seals (you can't just buy new correct Chrysler cylinders at the local auto store here is Australia). I cleaned the push rods up, and lightly honed the inside of the cylinder. Cleaned everything thoroughly and lubricated the relevant points, adjusted the shoes properly on both sides, bled them and voila! Working brakes with the best pedal feel since I had the car on the road 2 years ago. Total cost $13 for the cylinder rebuild and $4 for the brake grease. I'm pretty peeved with the brake shop as I'd asked them to check the rear brakes when they run new lines for me, but it's clear they didn't do much of a job. Thanks for all the advice everyone.

 

[MOPAR MARTY]

This should be a simple question for someone - I searched and found something recently on a similar situation this but can't find it now.

• The drum brake is grabbing on the passenger side rear - not much, but the wheel is warmer to touch than the other side and you can feel it when going very slowly.

• The car will still creep in Drive, but not as fast.
  
• The grabbing seems to come and go.
• I jacked the car up in the air and turned the rear wheels forward by hand - they turned about half a turn and locked up. I turned them backwards and they turned as many revolutions as as I wanted. Tried forward again and they locked up.
  
• I pulled the passenger rear wheel off and took the drum off - photos attached. Now they turned forward as much as I wanted with no lock up.
• I put the drum back on and they still turned freely - asked my son to push the brake while I turning. After he released the brakes the wheels were totally locked up turning them forwards. I turned them in reverse and they turned ok, and then if I tried to go forwards they turned fine. Repeated this a few times, same each time - locked in forward, reverse turns and also releases them.
• The shoes seem to have excessive wear on the lower quarter of the shoe - I assume this is where they are dragging. The cylinder also looks like it's leaking a little.
• Brakes were bled recently after I changed an axle seal on the other side - it's only started grabbing since then.

Any ideas what's going on?
View attachment 987170 View attachment 987171 View attachment 987172 View attachment 987173

the shoes got wet @ some point in time try replacing them