Over-enthusiastic rear brakes...

A slightly odd, but probably very straightforward question tonight...

I've got all the brakes buttoned back up, and all seem to be happy. BUT... the rears are a bit over-enthusiastic when you turn the wheel backwards. They'll go, at most, half a rotation, then they stop. Most of the time, they pick up almost immediately. They turn forwards until the cows come home, though.

At a guess, the top edge of the rear shoe is picking up on the drum and biting - because the hold-off spring is less than strong. It really is a bit half-hearted, tbh. It'll hold the shoe against the cylinder quite happily, but not a lot more. It's certainly not a patch on any of the other springs in the brakes.

Do I have some seriously time-expired springs? Are they located wrongly, very near the lower pivot? They appear to be right, going by the parts book and workshop manual PDFs.

Or will just chamfering the top edge of the shoe persuade it?

('80 88")

I recently had a similar issue on my 88" series 3, i'd fitted new shoes and springs all round and when rotating the rear wheels backwards they would lock up. I filed a small amount of material off of the top edge of the shoes and this has solved the issue.

However (from memory) i believe only the forward facing shoe has a top return spring, and if the rear shoe was the same i dont think the issue would occur.

A bit of chamfering helps but I've never 100% cured it on new shoes for mine - however after the first few reversing sessions they seem to settle down a bit.

dominicbeesley said:

A bit of chamfering helps but I've never 100% cured it on new shoes for mine - however after the first few reversing sessions they seem to settle down a bit.

Click to expand...

Thanks, guys.

Yes, the upper spring is only on the front shoe, and the back is more-or-less left to fend for itself. The lower springs are fairly weak, too. I've got some new ones on the way, and might even double-up, plus a bit of chamfer.

Don't overdo the springs by doubling up. If there's too much spring it will push the cylinder back in to quick and reduce the ability to do an emergency stop by double pumping the brakes...

I've chamfered the top of the shoe on one side today - and it doesn't grab any more. No, it just chatters badly instead. Definitely needs a better spring!

You are backing off by 2 clicks on the adjusters from just touching when rolling forward are you?

dominicbeesley said:

You are backing off by 2 clicks on the adjusters from just touching when rolling forward are you?

Click to expand...

Yep. Even backed right off, it's doing it.

The adjuster is, of course, on the other shoe.

Sorry, not spotted the 88"...rimmer bros do springs for a few quid so worth a try...

As I said previously mine did fart and clatter about when reversing for a while after fitting new pads but settled down in short time with no noticeable ill effects...

Well, the new springs were visibly shorter and feelibly(?) stronger... and sho' nuff, it works just fine.