Z32 BMC does NOT lock up brakes

[barshroom]

searched on every forum and it seems like everyone else has the opposite problem I do. Put in a Z32 BMC from togue factory to replace my stock S14 brake master cylinder. the brake pedal feel is absolutely great, much harder and not as mushy as it was before. The issue is that the car requires plenty of effort just to stop at any speed. brakes were bled plenty and it does not feel like theres any air in the lines. no leaks either. What could be causing this?


Z32 BMC 1-1/16
S14 chassis/skinny brake booster
Z32 front calipers
stock rear calipers

[S14rebuild]

Shitty brake pads cause this.... what are u running? Pads and rotors

[dorkidori_s13]

did you bench bleed the master cylinder prior to install?

and why are you using a z32 master cylinder? you dont need it if you are running Z32 fronts only.

[barshroom]

basic autozone brake pads and rotors. Never gave me any issues on old master. Running a z32 master because the pedal feel on stock MC was mushy and too soft for me.

[dorkidori_s13]

basic autozone brake pads and rotors. Never gave me any issues on old master. Running a z32 master because the pedal feel on stock MC was mushy and too soft for me.

ummmmk... i will ask again. did you bench bleed the master cylinder before installing? becaaaaaaaaaause if you installed the master cylinders straight out of the box without bench bleeding youre gonna have a bad time... get what im saying?

also, if your setup was spongy with the stock master cylinder... your problem lies elsewhere. my last S13 with Z32 fronts and stock rears felt pretty much like the OE setup on the factory S13 master cylinder, fronts locked up without issue and i never had a soft pedal feel.

might be time for you to check out either your brake booster or your one way check valve (or even the vacuum lines going from the booster).

[S14rebuild]

ummmmk... i will ask again. did you bench bleed the master cylinder before installing? becaaaaaaaaaause if you installed the master cylinders straight out of the box without bench bleeding youre gonna have a bad time... get what im saying?

also, if your setup was spongy with the stock master cylinder... your problem lies elsewhere. my last S13 with Z32 fronts and stock rears felt pretty much like the OE setup on the factory S13 master cylinder, fronts locked up without issue and i never had a soft pedal feel.

might be time for you to check out either your brake booster or your one way check valve (or even the vacuum lines going from the booster).


He states, the pedal isnt mushy, no long travel, and a hard pedal...all signs that there is no air in the system, and the master is functioning properly

[S14rebuild]

Calipers are mounted properly(bleeder at top)

But if ur 100% sure no air in system and u have a good pedal, then id say ur pads are shitty..or rotors glazed

Spend a little coin on nice ceramic pads, seat them in properly and report back..

[barshroom]

yeah my bad I forgot to mention that. bench bled the master until i had fluid coming out of the ports. made a mess but not my first rodeo. pedal feels extremely solid ill mention that again. Ive read that when swapping over to these MCs that people have issues not locking up their brakes. Im the complete opposite. I could put my entire weight on the brake pedal and it wouldnt lock. current brake pads have about 50% life on em.

[TheRealSy90]

Your tires are too grippy. Get less grippy tires and the brakes will lock up easier.

[dorkidori_s13]

I could put my entire weight on the brake pedal and it wouldnt lock. current brake pads have about 50% life on em.

might be time for some quality rotors and pads then. also Sy made a good point above... if youre running super grippy tires, youll be less likely to lock up.

[barshroom]

It’s not the fact that I’m terribly horny to lock up my tires (granted, I was able to do it on the old setup), it’s that the braking/stopping power of the car does not feel like it’s there.

[S14rebuild]

Change ur rotors and put good pads on..



Dont take the advice...

[barshroom]

ordered stoptech pads will let you know how it goes once theyre on

[dorkidori_s13]

ordered stoptech pads will let you know how it goes once theyre on

buy new rotors as well... or at least have your current ones turned (if they can be turned). no sense in bedding brand new pads into worn out or warped rotors.

[Bleakley]

Wouldn’t let me post last night...

Sorry for the f***ing million posts. Kept getting an error 403 or something every time I tried to post this sh*t all at once.

[Bleakley]

Still won’t let me post everything. What in the f*** zilvia.
I typed up a nice paragraph last night. Wouldn’t let me post. I’ll try and retype.
I’ve never really had issue with Autozone pads and rotors. I use them on all my cars. If tracked I use it there as well or name brand parts like hawk, brembo, etc.
The information being relayed here is misleading. Hope you don’t end up spending money you otherwise didn’t have to.

You’re not the only one who’s had issue with hard braking with this combination. (17/16” MC, Z32 front/stock rear, Manual booster).

If I have unusually high pedal effort and not enough braking torque in return, I would immediately question a caliper, or brake booster. (Unless the master cylinder to piston area is WAY OFF)

[Bleakley]

In your case / scenario, I’d verify brake booster is good, then maybe look into either a 1” master cylinder or an automatic booster if everything else checks out.

[Bleakley]

Verify engine vacuum, verify check valve, verify vacuum present at brake booster, diagnose / quick check brake booster (pretty easy).

[S14rebuild]

Verify engine vacuum, verify check valve, verify vacuum present at brake booster, diagnose / quick check brake booster (pretty easy).

Did u ready anything the op posted?

[anti tyler]

In a layman way of saying it, I get what's going on here.

On my first S13 I did a Q45 swap, and ended up with similar problems.

doing drive way brake bleeds aren't fun when you don't work in a shop with a fancy brake bleeding machine, but you should entertain the idea of changing your MC and booster combination to achieve a nicer pedal feel.

Stop wasting your time and money swapping pads and rotors around.

[S14rebuild]

In a layman way of saying it, I get what's going on here.

On my first S13 I did a Q45 swap, and ended up with similar problems.

doing drive way brake bleeds aren't fun when you don't work in a shop with a fancy brake bleeding machine, but you should entertain the idea of changing your MC and booster combination to achieve a nicer pedal feel.

Stop wasting your time and money swapping pads and rotors around.


Ops first post states he replaced the bmc with a new z32 one

[Bleakley]

In a layman way of saying it, I get what's going on here.

On my first S13 I did a Q45 swap, and ended up with similar problems.

doing drive way brake bleeds aren't fun when you don't work in a shop with a fancy brake bleeding machine, but you should entertain the idea of changing your MC and booster combination to achieve a nicer pedal feel.

Stop wasting your time and money swapping pads and rotors around.

Exactly.
I actually bought the Branick bleeder so I could have something similar at home. A little cumbersome getting it all setup and ready to use and whatnot for just ONE vehicle. But bleeding is so nice and pedal feel has always been great.


Did u ready anything the op posted?

Did you?

[S14rebuild]

Exactly.
I actually bought the Branick bleeder so I could have something similar at home. A little cumbersome getting it all setup and ready to use and whatnot for just ONE vehicle. But bleeding is so nice and pedal feel has always been great.




Did you?


Op states, no weird or unusual pedal feel or height......

[slow_sr20]

In my experience the z32 brakes even with the corresponding master just Do not work well. I was never able to get mine to lock up. Ran a similar setup on a m30 and only the rears would lock up. My car doesn’t make big power (not sure your needs) I’ll never mess with anything more than q45’s and some stainless lines. It works well. Plenty cheap and no caliper clearance issues.

Other random though... there was a correct z32 master, and a z32 master that was missing some sort of internal reducer fitting. Some of the z32 masters required that the fitting be cut out of your old master and pressed into the Z32. Good luck.

[Tempo]

Some of the z32 masters required that the fitting be cut out of your old master and pressed into the Z32. Good luck.

I had lots of trouble attempting to get that fitting out without damaging it. Ended up finding and using an Earl's fitting that did the same thing. Wish I had known about it before going through all that trouble :duh:

[S14rebuild]

In my experience the z32 brakes even with the corresponding master just Do not work well. I was never able to get mine to lock up. Ran a similar setup on a m30 and only the rears would lock up. My car doesn’t make big power (not sure your needs) I’ll never mess with anything more than q45’s and some stainless lines. It works well. Plenty cheap and no caliper clearance issues.

Other random though... there was a correct z32 master, and a z32 master that was missing some sort of internal reducer fitting. Some of the z32 masters required that the fitting be cut out of your old master and pressed into the Z32. Good luck.



With out that fitting installed the brake line could not be seated and would leak..that fitting has no effect on the workings of the bmc

[Bleakley]

And not to mention a moot point in this thread. The Touge Factory unit comes with a fitting installed prior.
I haven’t had actual first hand experience driving a car with ONLY z32 fronts installed, so no comments there.

Overall though, if you’re not able to lock up a portion of your brakes in a straight line test, you should put a little more effort into your system design. That’s performance being left on the table.
The edge of that tire to road contact threshold is the peak of braking performance.

I have a LOOTT of measurements regarding the S and Z chassis and will eventually compile it all into a thread here for those that are interested. Some of the things I still need to take measurements of are the pedals and pad heights for the S and Z chassis combinations.

[jedi03]

what silent points do we have on this thread? do you mean moot? I had this setup and worked great...pulled fitting using a screw on one and a pick on another...just slides right in and the brake line pushes it down...I would agree if the check valve is gone/reversed or the vacuum to the intake not correct then the assist wont work...sometimes a bad booster can cause it, otherwise would be needing to be bled more...

[jr_ss]

A 17/16 master from an S14 and auto booster ran my Z32fronts beautifully. I could lock them up if I wanted to, but that doesn’t aid in braking.

Have you tried an auto booster? I didn’t see any indication of it weeding through the verbal diarrhea above.

[barshroom]

I specifically went with the TF MC just so i wouldnt have to deal with the fitting BS. tested check valve, works good doesnt leak any air into booster. Yesterday morning I drove for a bit and in the first 10 minutes of driving around the pedal feel was different and I was able to lock the brakes rather easily. After getting out of my neighborhood the pedal feel went back to what it was before and no matter what I wasnt able to lock the brakes again... What the hell could it be?