Rear Brake problem

[pegboy]

As I rarely use my back brake, they have never been fantastic, it is now non existence. This might have been a result from the abuse it received after my track day. I got home and adjusted it up and the brake was really spongy and horrible, so I changed the fluid adjusted it up and had a full brake, but then the brakes dragged when not in use, so I loosen it off so there was minimal free play between the push rod and mastercyclinder, But now the brake does not work at all. I am thinking the rod has worn out and not enough travel to apply the brakes.

Does this sound right or do I need to look at the master cylinder, although it worked well when over adjusted?

Am I overlooking anything??

Any comment appreciated.

[big pete]

Sounds like you might have a stuck piston in the master cylinder, with not using the brake much they get a ring of debris round the seal , with you adjusting it up with the rod you may have pushed it past the ring and now its not returning. Thats a strip and clean and replace seals, on the other hand may just need bled , get a syringe and pump it back through from the caliper end at the bleed nippleto clear any air at the back and then work back from the master cylinder.

[BluprintZ]

I had the same problem last year with the rear brake sticking on.
I just removed the calliper, cleaned the pistons carefully, then put a piece of wood of a similar thickness to the pads between the pistons and pressed the brake lever until the pistons "trapped" the wood.
This enabled the pistons to come out a touch further than they would with the pads fitted, then it was just a case of lubing the pistons with brake fluid, applied with an artists brush, pushing the pistons carefully back then cleaning the excess fluid from them.
I repeated this a few times, then fitted new pads and re-assembled the calliper and all was good again.
The problem starts when the pads are allowed to wear excessively, allowing the pistons to come out more than they should, thus letting crud build up on the pistons.
Eventually, the pistons can't return and the crud causes them to stick.
It's all part of the maintainace regime, stuff like this happens from time to time, consumables like pads wear out and need replacing.

G : )

[pegboy]

Already changed the fluid but no difference, will look at it tomorrow when i have more time and remove the caliper and clean etc see what happens, hope that will sort it out.

Thanks

[big pete]

If you changed the fluid did it bleed up ok? If yes , your master cylinders ok and your caliper has seized.

[slob]

Once you've freed off the caliper, don't adjust it for zero free play, the book says 2mm free play at the master cylinder (not the pedal). It will seize on when it gets hot if you don't leave it some slack.

[pegboy]

when i changed the flluid it bled up good, but the the pads were rubbing as if they were slightly on. I assumed that the adjustable pushrod (pedal) was overadjusted so i backed that off so there was minimal freeplay but thats when i lost the brake again. It seems as if there is not enough travel in the pedal to apply the brake.

So the only time i have brake pedal is when i overadjust the rod?

I have new pads as the old ones are low but not on the wear indicators, i was going to fit them tomorrow and see if i can clean the brake system out, calipers, master etc.