Sticking Brakes

[joef]

Hey Guys,

I have a problem with my brakes ... they stick on! This has come and gone over the past few months but has got worse recently. At first i thought it was a problem with the front brakes so I rebuilt them using a new piston seal kit. I have also changed the front pads and rear shoes, and checked and cleaned everything.

What happens is that sometimes the brake pedal gets harder and harder with the brakes jamming on more and more. It seems only to be the front as they start to get hot and smell. I have found that if I pull over and wait for 5-10mins they are fine again and it then will not happen for a few weeks or a few 1000km. Then, suddenly for no reason I will start the engine after putting in some gas and within 5mins of driving off the brakes are jammed on...!

Years ago I had a similar problem with an old ford and it turned out to be the diaphragm on the master cylinder, we only worked this out after replacing every other part of the brake system.

Has anyone had any other problems like this? Any ideas how to work out what i need to replace. If it is the master cylinder can I just buy a diaphragm.

Once again a big thanks in advance

 

[ellington12]

joe,

i've seen this before and pinpointing the exact cause can be time consuming. there are a couple of things to try; (i suspect faulty brake hoses...they wear out from the inside and can start to act as a sort of one way check valve.)

once the calipers are locked up, crack open the bleed screw and see if the caliper frees up. if so, then you can rule out the caliper. it goes without saying but DO NOT DRIVE THE CAR WITH THE BLEED SCREW LOOSENED. if the caliper remains locked up despite opening the bleed screw, then the caliper is the culprit. (be sure however that the pads themselves aren't seized up in the caliper.)

if the caliper checks out, get them to lock up again and then loosen the fitting where the rubber brake hose meets the hardline. if the caliper now frees up, you've got bad rubber brake lines.

what did your brake fluid look like before you rebuilt the front calipers? if it looked like mud, you may want to pressure bleed the system with nice clean brake fluid.

 

[joef]

Thats great advice ... We are using the cruzer this weekend so I will take some tools and see if I can pin point the problem.

Thanks alot

 

[Toyrod]

Check the free-play between the pedal stop on the bucket and the brake pedal. Also, if the master cylinder was off prior to this problem, there is a clearance between the rod that extends from the booster and the piston in the master cylinder. If either of these clearances are too tight, or there is something preventing your brake pedal from fully disengaging, it could cause this problem.

Good luck!!

 

[joef]

Hey Guys,

Yesterday I finally got around to playing with my brakes. I got the brakes to jam on and opened the bleed screw on the front right hand caliper. Within a second the brakes freed up and I was able to drive again. Since then I have not been able to make them jam on again...why?

From what you wrote I must have problem with the caliper but now they seem ok, well until next time! I think I will strip down the caliper (again) and see if I can see any wear or anything that would cause them to jam on.

Thanks for you help.

 

[superjuice]

I had this same problem only it happend more often than not. I rebuilt everything short of the master, including the proportioning valve, calipers, lines etc. still locked up after only a few stops. I would carry a 10mm wrench and momentarily open the bleeder to releive the pressure (i got extremely effecient at this). long story short it was my master cylinder, i suggest you replace that before sinking as much money as i did into replacing perfectly good parts. Good luck bro and dont forget to grab that wrench

 

[joef]

Fixed I think

Hi Guys,

I stripped down the front brakes and blew the pipes out with compressed air. I also replaced all flex hoses and then bled the system with clean new fluid.

So far after 500km much on dirt roads up and down in the high Andes they have been fine....

Wish me luck

 

[joef]

Hey Guys,

Unfortunately it happened again. After a few 1000kms the front brakes locked on solid.....ahhhhhh. This time I have stripped down the master cylinder and cleaned it out. I would buy a new one but I could not find one in the small town I was in.

Better luck this time hey....!! There is nothing left to clean or change now!