rear brake rubbing, need suggestions

[JKB1957]

So I have a 1966 Sptifire Mk2 that I just rebuilt brakes. It ran fine for a few miles and then when I hit the brakes there was a "clunk" sound from the left rear drum brake followed by a "whump, whump, whump" sound that continues until I park the car. After the car sits it does the same thing, "clunk" followed by "whump". I bled the brakes on that side and loosened the adjuster. Friends think it could be the rear cylinder is loose. If so whats the fix on something like that. All the parts were new when I installed them.

 

[hondo402000]

take it back apart is the best answer

Hondo

 

[JKB1957]

I have it apart, can't see any obvious problems.

 

[Andrew Mace]

Any chance the backing plate itself is loose? The only way the wheel cylinder could be loose is if the two retaining clips went AWOL, but that should be fairly obvious (from the back side) even without pulling the drum off.

 

[bgbassplyr]

Check that the brake linings are the same radius as the drum, and that all the springs are correctly installed.

Sounds like one shoe is getting 'cocked' when applied. See if by backing up and applying the brake, the problem goes away until the next forward application.

 

[JKB1957]

Yes, after backing up the brake doesn't rub, until I hit the brakes going forward and the cycle starts again.

 

[TR4nut]

I'm assuming the cylinder is the same setup as on a TR4 - if so, can the cylinder move slightly on the backing plate? Helps to have a small amount of grease there, and it allow the brakes to stay centralized.

 

[JKB1957]

Thanks. I'm going to take the drum off tonight and take a closer look. I think I may be over looking something very simple to fix.

 

[Andrew Mace]

I suspect that WILL be the case!

 

[JKB1957]

Just to put some closure on this adventure. It turns out that the problem was with the adjuster. The adjuster is held in place by two studs that pass through the brake backing plate and are then attached with nuts and lock washers. Well one of these studs fell out. Everytime I hit the brakes the brake pressure worked on loosening the remaining stud until the entire adjuster assembly was loose. After this happened everytime I would hit the brakes the left rear shoe would come out of line and cause the rubbing.

 

[Andrew Mace]

Makes sense! Is it a new adjuster or an original? I've heard of this happening to more than one new adjuster....

 

[JKB1957]

Brand new adjuster with less then 150 miles on it.

 

[Andrew Mace]

Brand new adjuster with less then 150 miles on it.

Sad.

Still got the old one? if it's intact and the square post isn't too rounded, heat it up with a propane torch until you can turn the screw all the way out. Then hit it all with a wire wheel to clean it up, and put it back together with some white lithium grease (or whatever you prefer). Throw it on the backing plate and you'll be set for years to come!