brake locking up

[rps13 SR]

Hey guys i have a problem... i changed my master cylinder and a caliper!!! ok my car runs for like 10 miles and the brakes slowly locks up till i cant move... then i gotta let it cool for 20-30 min for it to free up again... and same thing happens.. i pulled off the my friend pulled off the brake booster hose and it helps a lot but will get stiff again... i dont know whats the problem... please help me..

[adey]

I would check the MC/booster to pedal linkage, you may have to adjust the pedal play (you can do that on our cars, right?), and pull the pedal up... that is, your pedal, when fully up (not stepped on) may still be putting pressure on/through the lines... um... that's all I can really think of. good luck?

[rps13 SR]

that dont seem to be the problem... i dont know what to do.. i'm gonna check the calipers pins and the shims... shims are rusted.. would that be a problem.. and also one of the pins were hard to pull out from the caliper.. maybe its bent so that can be a it right.. what u guys think

[formeRiceR]

this might be far fetched but I'm wondering if you properly bled the calipers and MC, having taken a few Chem classes maybe if there were a lil air still trapped, as you drive the brakes and calpiers get hot, the gas expands and clamping the rotors...strictly theoretical but hey it's food for thought...

[transient]

Air in the lines would expand when it got hot, but air is quite easy to compress and I don't think it would be able to hold the pressure like that.

[twitchy]

sometimes, and dont ask me why, I know it sounds retarded, but when you get grease on the rotors if thats possible, it does the opposite of what you think and makes the brakes lock up, but not like what your saying. It sounds like the caliper seal isnt pulling the pads back off.. I would check that out, and make sure you have lots of brake lube on the pins, can never have enough of that. Also while your at it, scuff up your rotors with some light sandpaper, that might help.

Honestly though it sounds like your seal, when you release the pedal, that seal is what pulls back on the pad to release it, if thats not doing its job, the pad will rub, possibly locking up.

[Rocketman]

Yeah i am still a newb to the boards but not to cars by any means.

couple questions first.
1 Do you have aftermarket brake lines installed?
2 Was it doing this before you put the caliper on?
3 Is it only one wheel or two?

Most likely if you haven't changed the brake lines it is either a bad brake line on the offending caliper, or the pins are bad or not lubrictated well enough.

When lines go bad, often times the form a valve inside that allowsw pressure to pass to the caliper but not back. A one way valve inside the lines so to say.

If so its a perfect time for braided lines :D

Hope that helps.
If not answer the questions and i should be able to tell you better. Be sure you got a good amount of syl-glide (brake caliper grease) on the pins too.

Rick
----------------------------
97 240sx base model, no mods yet. need to figure out what i want to do. :)
92 Sentra SE-R
CAI, ACT clutch, Fidanza flywheel, B&M shifter, NX brakes.

[kandyflip445]

Do you have ABS?

[rps13 SR]

thanks guys but i'm gonna figure it out tomorrow... kenny says it might be the pins cause when i changed the caliper one of the pins was dry and was hard to take out and put on the new caliper... bu the thing is that the brake pedal gets real hard to push down too.. and i think that both front brakes do it and maybe the back too... i'm not sure forgot cause when i had the car jacked up all the wheels were stuck while car was in nuetral and ebrake was off... ohh well hope i solve this soon