not pathy related but a brake problem!

[edicer2]

I just got done putting the z32(newer 300zx) brakes on my z31 (older 300zx)and bleeding them all 4 tires(3 times with no air in the line each time). But for some reason i cant get it to pump up. When i turn the car on the pedal goes right to the floor as if there is a bunch of air in it or no fluid. I took it on the road and from 20-0 i just slam the pedal and it hardly slows down then the rear brakes lock up and i slide. the front brakes did absolutely nothing! I did not upgrade the master cylinder. DO you think i need to? my factory brakes worked fine.

 

The benefit of z32 brakes is that they are much larger and are 4 piston instead of one

 

thanks!

[nige]

It sounds like you still have some air in the lines somewhere. I had the same problem and Simon suggested i gravity bleed the brake lines. Just leave the valve open for a few minutes and lightly tap on the caliper and lines in case there are some bubbles stuck in there. I just stuck a clear hose over the bleeder and watched for solid fluid to drip out. Don't touch the pedal when you are doing this.

 

You also may have a pinhole leak in one of the rubber lines (if you still have them), a loose banjo bolt or other fitting. Do those z32 brakes call for a different type of brake fluid than the z31 system? Check the simple stuff first. It sounds like you have a leak or air somewhere in the system.

 

The other possibility is your stock MC isn't good enough for those bigger brakes. I'm sure the z32 would have a different MC than the z31 because of their 4 piston calipers.

[Simon]

Yep....gravity bleed. Make sure you work from the furthest from the MC to the closest, one bleeder at a time. So rear right, rear left, front right, front left. I'm not sure if there's any other valves or anything on the lines in those cars, but your issue could be air stuck at one of them, similar to the proportioning valve on the frame of the WD21's.

 

Oh, and keep the reservoir topped up as you're doing this.

Edited September 17, 2009 by Simon

[sammyb33]

my guess is the MC cant keep up with the extra fluid needed to push those 4 piston calipers....Do the older ZXs still have the proportioning valve on the MC like the newer ones do? If not, I would go pick up a newer MC and slap it on

[edicer2]

Well i asked a few more ppl who have already done the swap and they told me that i might have air in the lines like you guys suggested. My MC should be good to handle those brakes they didnt need to upgrade them. I will try and tighten up the brakes lines if any are lose and also try the gravity bleed.

 

Also is it posible that since they are 4 piston calipers maybe the furthest piston from everything has air traped in it on the front brakes? The back brakes seem to work just not the fronts.

 

thanks for the help so far if anyone more ideas come up let me know!

Edited September 17, 2009 by edicer2

[Precise1]

Yeah, I was guessing that there might be air trapped in the new calipers. I had this happen when I converted my bug to disk brakes. I removed the caliper and rotated it about, tapping it and ended up with the bleed nipple straight up (the highest point), and then bled them like that. Did this a couple of times and they worked. A little bit of a pain, but a 'free' fix. If you have a similiar issue, gravity bleeding will do nothing, but try it first...

 

B

[unccpathfinder]

also check your rear shoes (if it has shoes) and make sure they are adjusted correctly...I did a camry not too long ago and bled it for like 3 days and had the same thing your going through and I checked one side and it was good...anotehr guy came over and checked the other side and it wasn't adjusted...he adjusted and bam full pedal...I guess the same is true too for very worn pads...she also had no front brakes and the LR would lock up but all of the fluid was running to the RR and there wasnt enough to create enough hydraulic pressure to clamp the front calipers

[nunya]

Is it an ABS system? I've had a coupel cars that wouldn't bleed correctly with ABS unless the car was running(thing they were GMs but it's an idea)

[unccpathfinder]

that or the ABS valve is trapping air (had that trouble with a 94 pathy before)

[edicer2]

ok ill try tilting the calipers a bit. it has disk brakes all around and the rears have new pads and worked fine before swaping the front i think they still do work they just dont do much since the front does most of the braking. Also no abs came on the US models