Going down hill, hard brake, bam foot to the floor. Right rear wheel cylinder spat it's seal. Replaced it with a brand new one, didn't do the other side because I cbf'ed. Bleed up, go down street to test it, bam the left rear goes. (Karma). Replace that side too.. And this is what confuses me, start bleeding the brakes with my brother pumping the pedal up when all of a sudden the brand new right rear cylinder pops.

 

Back to square one. Can't work out why it would pop a new one? Read through a couple threads and this is what I've put it down to.

 

1. AE86 JDM Brakes up front somehow causing the brake bias to be out and too much pressure going to the rear thus blowing seals.

2. Drum shoes are low and drums themselves are old (Most probably never been replaced) with 280xxxkms on the car. Pushing piston too far?

3. Car hates me.

 

Was driving around for ages with the two old cylinders and the brakes bled but not 100% and had no problems til I stomped the brake.

Didn't fully adjust up my right rear shoes when I put the new one in. (Still ebrakes fine).

When I had only one new cylinder in, fully bled with a really firm pedal. Pushed down, was braking really well for a distance then went pop.

 

 

Any ideas/help would be greatly appreciated.

By now the shoes are full of oil anyway, so go buy two new slaves and a set of shoes. New slaves are less that $30 each. Start from scratch and get everything set up right.

 

I can't see how a piston can ever come out of a slave cylinder enough to let the seal out, so something is very wrong in your setup. Even with worn shoes and worn drums it shouldn't happen.

Your brake drum inner diameter is too large like a rotor wearing thin. There could be a blockage in the primary lines over pressurising your rear cylinders or yes rear brake linings too thin.

The ae86 and ke70 front piston diameter are very close if not the same.