5 replies to this topic

[Ricester]

Hey,

 

I managed to take my car on a very light maiden drive the other day. Happy with how the engine went. However, on braking, I noted there was barely anything there. I was not confident and even pushing the pedal all the way down I could feel the master cylinder piston on full travel but nothing from the brakes. 

 

Ive stripped the rear drums off to find one of them was soaking in brake fluid. It looks like the cylinder, which is brand new, has leaked. I stripped the shoes off, cleaned up and tried to bleed. I got a weak bleed off that side. I then bled the other side and the front and retried the brakes. On pumping the brake pedal with all bleed nipples closed and master topped up, the OTHER cylinder went! I heard a "psssssst" and saw the fluid on the floor. see attached pic. 

 

Its leaked from the outer rubber part which, as far as I am led to believe, should have grease inside it, not brake fluid. Does that mean an inner seal has failed? If so, its happened on both sides, one while driving. And these are brand new. Car has literally been driven less than a mile with them. 

 

Is there something Ive done wrong here? Before I go back to the seller. 

Attached Files

•  brake cylinder leak.jpg   32.09K   2 downloads

[imack]

I'd say somethings fitted incorrectly as it looks like the piston has popped out of the cylinder. More photos showing the entire back plate a shoe assembly would be helpful.

[Quinlan minor]

Hard to be sure from that photograph, but it looks like the piston has exceeded it's travel limit, in which case it will be past the seal.

 

Are the shoes new? It's best to replace them if they have been contaminated with brake fluid.

Have they been adjusted properly? Are the return springs new/on the right way?

[Ricester]

Thanks guys, so the first one that went (when driving) the shoes werent adjusted. Id forgotten to go back to them and adjust, so it is likely that the piston exceeded travel and popped past the seal. 

 

The second one, I was pumping the brake without the drum on, so it most likely went past the travel and done the same. I now understand this, I didnt even think about it. Thanks again. 

 

Assuming I can strip the cylinders down and the seals arent ripped, is it just a case of popping the piston back in and giving them a good clean, grease the pistons again etc or are they gone and I need new? 

 

Yes, I had to bin new shoes on one side. Frustrating. 

[Spider]

Assuming I can strip the cylinders down and the seals arent ripped, is it just a case of popping the piston back in and giving them a good clean, grease the pistons again etc or are they gone and I need new?

 

Yes however be aware that for rubber parts like in these you would use Rubber Grease. Ordinary Grease will destroy the rubber.
 

[Quinlan minor]

Is it just a case of popping the piston back in and giving them a good clean, grease the pistons again etc or are they gone and I need new? 

 

It should be. Don't grease them, just lube them with brake fluid and gently push them in, don't screw them in.