S14 Brakes lock up. Lock hard. No release.

[DeeJay1337]

Ok, I have no clue as to what this is... I'll be driving and use my brakes and they will release only a little bit. And then i'll brake agian and will only release a little bit agian... so now its braking on its own. it will get to a point where teh car will no longer drive. brakes will just lock up.

So i release the fluid on the bleeder and its fine agian until i start braking agian.


I thought this was my front calipers, so i upgraded to brembo's off a g35....then I thought this was a bubble in my brake lines so I bleeded the lines... agian same thing... I thought this was my Brake master cylinder, so i upgraded to a bm57... still same thing!

any ideas?

Car is a 97, KA-T (if it matters) fronts are Brembo calipers from G35 rears are stock...

i bleeded the entire system like 3 times already... I cant get a clue as to what is going on!

[iLagX]

brake booster? z32? s14 auto brake booster will help.

[Hashiriya415]

Misadjusted push rod from pedal to booster

[DeeJay1337]

But why would it get misadjusted out of no where? How do I adjust it back?

[essforteen]

Boiling Brake lines from your KA-T manifold?

[Rabboni]

Did you change the lines when you did the upgrades? Ive heard of rubber lines degrading internally and forming a flap that allows fluid past but doesnt allow it to return. Its rare, and Ive never personally seen it, but it is possible.

[Hashiriya415]

Originally Posted by DeeJay1337

But why would it get misadjusted out of no where? How do I adjust it back?

See there is a lot you need to learn, you need freeplay. Best for you to open up the service manual and get familiar with the brake pedal adjustment procedure. Who knows you might even have something stuck between the pedal, that is not letting it travel all the way back. Might even have some bent parts, you should inspect and adjust. And yes heat can cause fluid to expand, but if correctly adjusted the return valve always stays open letting the fluid go back up into the reservoir.

[klits562]

Originally Posted by Rabboni

Did you change the lines when you did the upgrades? Ive heard of rubber lines degrading internally and forming a flap that allows fluid past but doesnt allow it to return. Its rare, and Ive never personally seen it, but it is possible.

He speaks the truth!

Also im assuming you changed the fluid when you upgraded to the brembos right?

[DeeJay1337]

Its not the boling fluid trust me guys... The turbo doesnt even get hot, trust me its like driving a couple of blocks.

[hulkster_s13]

pushrod to brake master. the one behind the master cylinder. turn it in like 1.5 turns. same thing happened to me. brakes gradually locked up.

[driftlife]

hahahaha the same thing happen to me s14 but mine was a 96 n/a.....i did the same thing you did but they still locked up....it sucked [email protected] just traded it for a s13

[xtopgun32x]

mastercylinder could be dead. or it could be too weak for your upgrade so it doesnt return the pistons completely. and if the master cylinder is good you could try synthetic brake fluid(assuming youre not using it already) because it could withstand higher temps to prevent boiling from the turbo/manifold heat. ive also seen heat blankets on master cylinders/resevoirs.

[xtopgun32x]

im just saying its really common to upgrade the brakes and shit goes wrong. when you think about it youre putting brand new awesome brake calipers on a 10-20 year old master cylinder. that piece of sh*t is probably worn out..not to mention it wasnt built for z32 or z33 brakes or calipers with at least 4 pistons...

[dalers08]

same thing happened to me. brake booster

[xtopgun32x]

i keep replying like an ass. but i just remembered when i did a z32 upgrade. i did a bleed at the the calipers and my brakes were tight. then i did a bleed at the master cylinder and with one pump they were magically working. like i said i hate to keep replying but thats what fixed my brake tight issue.

[dalers08]

Heres what you do. Drive around the block until the brakes lock up again. Pull off the vacuum hose to the brake booster. If the car starts rolling away get a new brake booster.

[DeeJay1337]

So... Here's what happens. dalers08 was right. My brake booster is shot. I unplug the vacume line on teh booster and it starts sucking like crazy, (car still on) plug it back in and viola! Car goes rolling easlily.


So my question is now, A new Brake booster, does it matter ABS or not? also years matter?


So here's my upgrade setup for all you to know

G35 Brembo Calipers, With Brembo Solid rotors. SS Brake lines. BM57 and Dot 4 Brake fluid. Rears are just slotted and drilled rotors.

Such a hard thing to get teh 300zx Ebrake assembly and ebrake cables oh such a headache. But its ok! i'll get my rear brembo's too!

[DeeJay1337]

Stil need some help, wondering if ABS or non abs brake boosters matter.

[endlessboost]

I dont think it would matter since you've got upgraded brakes. I'd get a z32 brake booster since its dual diaphram. It'll def help with brake pedal feel.

[projectRDM]

S14 auto and ABS boosters are also dual diaphragm. 205mm/180mm versus the single 230mm unit found on manual and non ABS cars.