rear drum brake drag

[Billccm]

Car is a 1968 Road Runner, stock rear 11 inch drums, WITHOUT self adjusters.

Drove the car Friday night and noticed when braking from 45MPH I would hear a clunk from the right rear. It sounded like the old self adjusting when you back up and brake kind of clunk. As time went on with every clunk I could tell the right rear brake was starting to drag.

Got the rear wheels off and the right rear drum was much hotter than the left. The left rear drum slide off with some walking (like normal), the right rear drum required many, many turns of the adjuster to get the drum off. It was not near locked, but it had massive drag.

I see nothing visibly wrong. All hardware and springs are in place. Shoes look good. No leaks or wetness from the wheel cylinder.

Re-adjusted the drums and went for a test drive. All is well. No clunk-No drag, and a few panic stops from 45MPH are really good!

Drove to a car show without issues last night until returning home. Stopped from 45MPH and heard the right rear 'self adjusting' clunk. After three stops I could tell I had brake drag on the right rear.

Not sure where to start? Any help is appreciated.

 

[dadsbee]

My Bee use to do that and I had to remember to stick my toe under the brake pedal and lift it up or my RR would drag, as the master cylinder spool wasn't fully returning without lifting the pedal.

 

[Billccm]

My Bee use to do that and I had to remember to stick my toe under the brake pedal and lift it up or my RR would drag, as the master cylinder spool wasn't fully returning without lifting the pedal.

Did you hear a 'clunk'? I wonder why only the right rear would be effected? The master circuit splits evenly at the junction block to both wheel cylinders?

 

[dadsbee]

I think with mine the other three wheels probably had better return spring tension and the RR was the weak wheel so it dragged vs being able to fight the residual line pressure. If I lifted the pedal it would release. Just throwing it out there as an easy thing to try before tearing into things. I don't remember a clunk, but it was 20+ year ago and I don't remember lunch yesterday! LOL

 

[threewood]

Return springs worn?
Soft line to drum bad, causing one way valve affect?
When was the last time you had them apart? No self adjusters, just the star wheel held by spring pressure?

 

[pnora]

Make sure you have it adjusted correctly. Parking brake has to be fully backed off or else the shoes will not sit on the anchors. So fully back off the park brake, adjust the service brakes and then adjust the park brake.

 

[Billccm]

Return springs worn?
Soft line to drum bad, causing one way valve affect?
When was the last time you had them apart? No self adjusters, just the star wheel held by spring pressure?

I think the only soft line is to the junction block that splits to both rear drums. All of the lines, soft and hard are less than 6 years old.
No self adjusters as stock.
Maybe I will get a hardware kit and change out the springs?
Question: Most parts houses only list 'front' for 11 inch drum hardware kit and NO rear kit? I assume front an drear are the same hardware?

 

[Billccm]

Make sure you have it adjusted correctly. Parking brake has to be fully backed off or else the shoes will not sit on the anchors. So fully back off the park brake, adjust the service brakes and then adjust the park brake.

Good point here. In fact I have ordered a new parking brake cable as the release has become hokey from time to time.

 

[Billccm]

Another question: can I use this kit and just leave off the self adjuster hardware?
https://www.ebay.com/itm/224468264079?hash=item344359e48f:g:uFMAAOSwlStaw~GM

 

[Photon440]

Could you not use that kit to get the self adjuster option?

 

[oldbee]

Good point here. In fact I have ordered a new parking brake cable as the release has become hokey from time to time.

Could be the rt.rear park cable is sticking also.

 

[oldbee]

Another question: can I use this kit and just leave off the self adjuster hardware?
https://www.ebay.com/itm/224468264079?hash=item344359e48f:g:uFMAAOSwlStaw~GM

You could, but have to use the original spring over the adjuster. It's different. I cannot tell you how many brakes I've seen with problems from a broken adjuster cable(for self-adjusters) . Usually not a problem with our low mileage cars,tho.

 

[Fran Blacker]

Spring keep adjuster from turning. Do you have this spring?

 

[Billccm]

Spring keep adjuster from turning. Do you have this spring?View attachment 1156208

Yep the spring is over the adjuster and turning the adjuster takes some effort to click with the spring.
The clunk noise is a clue, but I can't figure it out.
Park brake cable may be part of the cause. New one ordered and I'm just going to do the $9 brake hardware kit from O'Reilly as a precaution.

 

[Cranky]

The clunk might be the backing plate loose?

 

[Fran Blacker]

Is it possible one of the spring studs that hold shoes in place is to long? Shoe moving around. Like the e brake idea. Wonder if rubber hose internal may effect passengers more because it's further away?

 

[Billccm]

I read the "Service Brakes 10-11" section of my factory service manual. Under symptoms for brake drag parking brake cable adjustment and weak return springs are possible causes 3 and 4.
Drawings for the parking brake cable are not the best so it is difficult to visualize replacement.
Hopefully I'll have the new cable so I can tackle this next weekend.

 

[dadsbee]

If you are doing the rears, this is how to remove the cable from the backing plate. 14mm box end will depress all the tabs..

 

[Billccm]

If you are doing the rears, this is how to remove the cable from the backing plate. 14mm box end will depress all the tabs..
View attachment 1156277 View attachment 1156278

Appreciate the tip.