Brakes are locking up on me. PLEASE HELP

[shotgunhunter4]

I have already searched and searched and because i search so much I have close to no posts at all. Heres my situation, about a year ago I bought a 95 240sx with a blown engine off here and finally about a month ago was finally able to get it to run. I knew i would have to change the brakes so thats what i did. I changed all the pads (I have all disc brakes) and turned the rotors. I then took if for a test drive about about 5 mins into it, I noticed i wasnt coasting very far and it was taking much more gas to keep the car moving. By the time I got home they were smoking like crazy. I then rebuilt all of the calipers and lubed the pins that slide the caliper on and off the rotor and made sure they were working well. I then took it out for another test drive and about 5 min later the same thing started to happen again. So I went oh here to figure out what the problem could be and I guess it could be a bad vacum line from the brake booster. but my question is how do I check the brake booster and master cylinder? What do i look for when inspecting the lines? Could a slight crack in one of the hard lines from the master cylinder do this? What else could this be from, am I missing anything? I really want to get this car up and running. Thank you for anything and everything.

[Var]

I'm not to good with brakes..but from what you stated, all those problems would reduce pressure, not increase it.

[mrmephistopheles]

adjust your brake booster rod (unbolt MC and use small crescent or 6mm(?) wrench).

[shotgunhunter4]

The thing is is that its a gradual thing and gets worse and worse but i only start to notice it after about 5 min. and if i go back out a hour or two later i can drive it for another 5 min or so.

[mrmephistopheles]

yeah i get it. your brake booster rod is extended too far which is causing your brakes to drag.
as they drag they buildup heat.
Once the rotors expand and the pads get hot, they lock the wheels up.

DO WHAT I SUGGESTED, AND IT WILL BE FIXED.
I'd recommend a full clockwise turn to start with.

[shotgunhunter4]

alright man sounds good. Ill let ya know how it goes. THANKS


-Jeff

[Phlip]

^^^ He was right when he told me to do the same thing on my car... I also took the precaution of going ahead and getting new pads AGAIN and changing ALL of my brake fluid as well, zero issue since.

[270R]

bleed your lines, maybe theres moisture in the lines. you do know water expands when hot right?

[Bryants95240sx]

need to adjust the brake booster. had the exact think happen on my 280zx

[270R]

would'nt the booster give problems as soon as you get going.

He says after ...5 mins.... the car goes into lock. wont it take about 5 mins for heat to build? or is there something about the booster that im missing out on?. just want the knowlege lol...

[Bryants95240sx]

no b/c as the booster is used more it affects the brakes more. This is how it happend on my 280 it would be fine when you first started driving but as you used the brakes more and more they would begin to lock up. Then we would let the car sit for a while and it would be fine. then the same thing would happen again

[dunno]

Is your e-brake on? :)

[270R]

ok. ill go with what your saying b/c u had this problem before. but all I ask is mechanically explain yourself.. that sitting for awhile you speak of can let the lines cool down and the moisture condense again... atleast thats what I was told...

[270R]

whatever get on with life now........ :barf:

[mrmephistopheles]

270R, i'll break it down Barney-style for you:
The rod in the booster is too long for him right now.
That means it's just's like he's resting his foot on the brake pedal.
Because of that, his brakes are heating up and eventually locking.
Once they cool, he can keep going,
but until he 'takes his foot off the brake'
he'll keep having this problem.

It's not a moisture issue. Water in the lines would cause inadequate pressure to the caliper pistons and insufficient braking.

[shotgunhunter4]

Thanks mrmephistopheles, I took my entire brake booster off and fiddled around with it. It seemed like the rod was just getting stuck somehow. So i just kept working it and getting it loose and put it all back together and took it out for probably a whole 10 min run lol. But it seems to be working now. Thanks guys.

[ranisron]

I got the same problem with mine right now... trying to fix it tomorrow yay!

[hegamiz]

hmm... ok I have a question now....
Well I have the same issue with brake drag...
did rebuild, bleed the lines, new rotors, new pads blah blah blah...

but my question is
mrmephistopheles recommended one full clockwise, which i did, plus another 1/2 turn... still have brake drag
so
is there a downside to turning the rod too much??

adjust your brake booster rod (unbolt MC and use small crescent or 6mm(?) wrench).

BTW it's a 7mm wrench for anyone who'd care