Ghey Ghey Ghey 300zx Brake Mushiness

[opponheimer]

Just installed 300zx 26mil calipers and rotors and pads, with splparts lines, tightened them way the fuck down, no fluid leaks at all. The car when OFF the brakes feel stiff.

When the car is on, the initial press of the brake pedal feels mushy as hell. As you pump the brakes it gains pressure and when you let off, it loses all pressure, yet NO fluid leaks.

What am I missing here? ps. the bmc and drum worked fine on stock S14 brakes. (Car was an auto too).


THanks!

[95Kouki]

did you happen to re-bleed the brakes after you put the new calipers on?...also abs equipped?

[opponheimer]

Rebled for 2 hours straight, no abs

[95Kouki]

did you use a vac bleeder or did you pump the pedal...how many miles on the chassis?

[articdragon192]

Stock or Z32 brake master and brake booster?

[c2autoinc]

Either there's a leak or you're not bleeding them right. The only

[Helghast]

Use braided Lines.
Bleed Properly.
Will still be mushy.
Update BMC and Brakebooster.

Search.

[69datsun510]

Your description of your problem is still air in the system. While you spent the time bleeding the brakes by hand, you still need to bleed them in the correct sequence and using correct method. Make sure you bleed them correctly, all four corners, and in the correct sequence. I usually bleed them good enough to get it to a shop or someone who has a pressurized brake bleeding system. Make sure you use new copper washers and don't over tighten the banjo bolts. I have often bleed systems by hand, only to still have air in them. I've been so mad, I was going to buy the professional bleeding setup. I think they go for around $300. There is just no substitute for pressurizing the system and bleeding out the pockets of air. It takes just a few minutes per corner. I hope this helps you out and good luck. I feel your pain!!!

[boycelaforest707]

Either there's a leak or you're not bleeding them right. The only

I am same problem but replaced brake booster, rubber inside had small hole.. everything worked great.
:bigok:

[koukimonster139]

same problem ^


its the brake boostttteerrrr

[Racer X]

read a haynes manual you described a mc leak almost word for word

[unwtdhero]

when ever you bled the system did you make sure the brake cylinder always had fluid in it? its a duh question, but it happens.

[opponheimer]

Im going to bleed rears tomorrow.

[articdragon192]

Stock or Z32 brake master and brake booster?

Hmmmm ?

[projectRDM]

Are the bleeders at the top of the calipers? If not, switch sides.

[nissan_driver24]

sounds like you still have air in the system. usaually when the brake master cylinder is out the pedal will drop to the floor even without the booster work (or when the car is on). My suggestion is to rebleed all four corners... starting from the futhest wheel from the bmc... which be passenger rear.... then driver rear... then passenger front... last driver front.... i did my full z32 brake swap not too long ago and didn't have a problem just did when i stated above. good luck

[opponheimer]

Are the bleeders at the top of the calipers? If not, switch sides.

The bleeders are not at the tops, is it customary to switch the bleeders and the line positions?

[projectRDM]

The bleeders are not at the tops, is it customary to switch the bleeders and the line positions?

Bingo. The bleeder has to to be at the top side of the caliper, otherwise you're trapping air in the bottom that won't press out. Swap calipers from side to side.

[Dripht240]

everything ive ever EVER read about the 26mm z32 brake swap is that you absolutely MUST use the z32 BMC, otherwise youre not going to be putting enough fluid pressure to the brakes, thus leaving soft mushy brakes... do a search and youll see... gl

[opponheimer]

everything ive ever EVER read about the 26mm z32 brake swap is that you absolutely MUST use the z32 BMC, otherwise youre not going to be putting enough fluid pressure to the brakes, thus leaving soft mushy brakes... do a search and youll see... gl

Well I think R240NA is right, went bleeding the brakes for an hour and at random times nothing/no fluid would even come out. So I guess ill have to swap calipers.

[RUTH'LESSDET]

had same problem with mushy brakes 26mm @ first bleed them correctly added braided lines front and rear good 2 go now

[opponheimer]

Swapped calipers and bang, everything works, +1 for r240na, saved me for the millionth time. Thanks man!

[burnsauto]

everything ive ever EVER read about the 26mm z32 brake swap is that you absolutely MUST use the z32 BMC, otherwise youre not going to be putting enough fluid pressure to the brakes, thus leaving soft mushy brakes... do a search and youll see... gl

well its not really a MUST. plus...hes got an automatic setup anyways, so his booster/master are a little larger compared to the 5 speed versions..

[projectRDM]

The auto S14 MC/booster setup does fine with Z32 brakes, fronts only or all four corners. The MC is 15/16", the booster is a dual chamber, 205mm/180mm unit. Plenty of pressure for the larger calipers.

[cdlong]

everything ive ever EVER read about the 26mm z32 brake swap is that you absolutely MUST use the z32 BMC, otherwise youre not going to be putting enough fluid pressure to the brakes, thus leaving soft mushy brakes... do a search and youll see... gl

people often lump mushy and long travel together. you could have a stock MC free of air and it will still stop the car fine, the travel will just be long and it will be easier to push. with a z32 MC the pedal would be harder to push, but you could still have a mushy pedal if there's air in the system.

random note, i'm not sure if you meant it this way or not, but there's no difference in pedal feel between the 26mm and 30mm brakes.

[opponheimer]

Well these brakes feel phenomenal and are easily controllable. They don't just lock up unless I want them to. Great with the auto brake mc and drum. Excellent upgrade imo... glad i pieced it together.

[Tenchuu]

glad you fixed it, it is surprising how many people overlook that bleeder issue.

[articdragon192]

Haha, I remember I did that with my Q45s. Good to hear you got it fixed.

[opponheimer]

Thanks guys.................

[scarecrow27]

if your going to upgrade your car at least do it right think about it your going up to 4 pot calipers ur gonna need the corrisponding brake cylinder and booster.

[ALEXTHESUS*PECT]

we just went through this yesterday night when changing the brakes over!

[projectRDM]

if your going to upgrade your car at least do it right think about it your going up to 4 pot calipers ur gonna need the corrisponding brake cylinder and booster.

No, you're not. As already discussed the auto MC and booster work fine.

[AbsoluteZero]

we just went through this yesterday night when changing the brakes over!

Yes we did! Now its fixed though! Swapped sides last night and everything works perfectly! :bigok: