Z32 front calipers, stock rears not working

[khilgers]

I recently upgraded to 30MM Z32 calipers up front and left the stock calipers in the back. After getting everything bolted up, front caliper, HPS pads, stainless lines it appears that my rear brakes are not really doing anything. Yes, I bled the entire system to ensure that their is no air in the lines, but the rear brakes don't seem to be doing anything. I figured it could be a couple of things:

1) I need to use DOT 5.1 brake fluid, I used DOT3,4 compliant fluid.
2) I need to upgrade to a bigger master cylinder.

Currently I am running the stock master cylinder with the automatic brake booster on my '97 240SX. If I need to upgrade the master cylinder which one would you suggest, 1" or 17/16" Or should I start off by changing out the fluid and go from there?

[Ricks15]

Dot 5 is over kill sick with 4 if you still useing the stock brake MC then thats the reason why, you're brake bias isnt dialed in right you need something a little better in the rear.

[khilgers]

Dot 5 is over kill sick with 4 if you still useing the stock brake MC then thats the reason why, you're brake bias isnt dialed in right you need something a little better in the rear.

I am using DOT 4 fluid, but what do you mean by something better for the rear? Like Z32 calipers or what?????? I don't want to go through putting the Z32 calipers in the rear, that's why I decided to keep the stock ones, but just upgrade the pads and lines.

As for brake bias am I better of getting a different master cylinder?

[Ricks15]

what I meant was something better like a bigger caliper or some shit like that, Change the MC its a must put better pads in the rear and lines maybe that will give you more brake strengh.

[khilgers]

I kept the stock rear calipers, but upgraded pads and stainless lines already. Is a MC my best bet at this point? And if so which one 1" or 17/16"?

[aznpoopy]

was your car auto stock?

15/16 master cylinder is what the general consensus was for a z32 front stock s14 rear set up. and if your car was auto, then that's the master cylinder you already have.

[khilgers]

was your car auto stock?

15/16 master cylinder is what the general consensus was for a z32 front stock s14 rear set up. and if your car was auto, then that's the master cylinder you already have.

Yes it is an automatic. When I was finishing things up and the car was still on jack stands, just for shits and giggles I decided to put the car in gear and see how well the rears were still working. At 10MPH the rears WERE NOT working at all. The wheel stopped eventually, but it's as if I had no rear brakes what so ever. Opinions?

[aznpoopy]

your rear brakes may simply be shot.

a month ago i put on 4 calipers i got with my 5 lug swap. bled and everything. no brake pressure at all. thought it was the m/c. drove around on an ebrake and engine braking. mad scary. next week, we swapped the master cylinder to a new one. STILL no brake pressure. in desperation, i put my old calipers back on and bled em. voila, good as new.

still don't know why the other calipers didn't work. no external leaks or anything. sometimes they're just shot, instead of frozen.

[khilgers]

so it may NOT be a proportioning issue that I could solve with a bigger MC, but simply that the rear calipers are "shot". I just have a hard time buying that. Seeing is there are no leaks, they are not frozen. I mean a caliper just doesn't go bad without signs of wear, tear, and eventual breakdown....does it?????

[aznpoopy]

that's what i thought until i had my little problem.

no leaks or anything. looked like regular old s14 calipers.

throwing on my old calipers at 8pm was really out of desperation. not a calculated fix.

[khilgers]

I've got to get some sleep, but we'll continue this tomorrow. Thanks.

[g6civcx]

The piston may be seized. You won't be able to tell unless you took off the caliper and inspect.

[cgguy]

Simply replacing the fronts with the 300zx parts is not going to change proportioning to the point that your rears dont engage. If you didn't break anything durring your install it likely one of 2 things.

Did your rears work fine before the swap? If not check the rear calipers to see if the sliders are siezed. The sliders should move freely with very little effort. If they dont then you need to un-sieze them and clean them up. (I can go into detail later if that's your problem)

If everything was fine before the swap then I'd say it's 99% chance you need to re-bleed the whole system.

Follow this bleeding order:

1) Bleed the Master (make sure it stays full during the rest of the bleed...get a friend to help)
I'm assuming you have ABS so turn off the ignition and disconect your battery.

2) Go in this order: Right Rear, Leftr Rear, Right front, Left Front

3) Use a friend..I dont trust speed bleeders.

good luck.

[g6civcx]

FYI for those who have S13s. This is from the S13 FSM.

http://g6civcx.angryhosting.com/S13/Tech/BleedBrakes.jpg

[Nostradamus]

I have 30mm fronts and stock rears on my 98 and the proportion is PERFECT. I don't think it could get any better. I used Blue Racing fluid and I bled passenger rear, driver rear, passenger front, driver front so the above post ^^^ is interesting since I've always thought you should do the furthest calipers first. The best thing about using the blue fluid is you can see when it’s coming out because it’s blue. :bigok: I don’t think it’s your MC.

[cgguy]

I bled passenger rear, driver rear, passenger front, driver front so the above post ^^^ is interesting since I've always thought you should do the furthest calipers first.

You're right about that, BUT, on S14's with ABS the MC feeds the ABS actuator which is located on the passenger side firewall. So, in reality the drivers side front caliper is further away from the MC than the passenger side front. (based on length of brake line to the ABS actuator.)

As for the rears physical distance from the MC is roughtly the same since the brake line splits at the rear axle, BUT, Nissan says you should bleed the Driver side rear first so that's the way I do it.

FYI, like most other people here I have 30mm fronts and stock rears with stock MC and the proportioning seems fine, besides, with ABS propotioning becomes sort of a mute point anyways.

[Nostradamus]

You're right about that, BUT, on S14's with ABS the MC feeds the ABS actuator which is located on the passenger side firewall. So, in reality the drivers side front caliper is further away from the MC than the passenger side front. (based on length of brake line to the ABS actuator.)


I don't have ABS so I don't see why bleed the driver sides first.

[aznpoopy]

the brake lines are laid out so that the two lines that go to the rear run along the passenger side of the car. so the line that extends from the rear running to the driver side rear is actually longer then the line that extends going to the passenger side rear.

edit: ok that was mad confusing. a picture is worth a thousand words.

http://i10.photobucket.com/albums/a104/kirinpoopy/brakelines.jpg

[Nostradamus]

Ahhh yes, just a tad longer the driver sides are.

[khilgers]

The brakes were working fine before the swap, because when I changed out the brake pads I had to push the piston in, in order to get the new pads in. As for the slides I pulled all of them out, cleaned them up, and regreased accordingly.

As for bleeding the master cylinder, how exactly do you accomplish this? This may be my problem since I just bled the right rear, left rear, right front, then left front.

[cgguy]

The brakes were working fine before the swap, because when I changed out the brake pads I had to push the piston in, in order to get the new pads in. As for the slides I pulled all of them out, cleaned them up, and regreased accordingly.

As for bleeding the master cylinder, how exactly do you accomplish this? This may be my problem since I just bled the right rear, left rear, right front, then left front.


Hmmm, well that might be your problem right there. The rear caliper pistons MUST be turned back in (clockwise) never pushed in with force. Hopefully you didn't toast the inner assembly parts. Rotate them back out (counter-clockwise) then rotate them back correctly.

Otherwise bleeding the MC is pretty much the same as bleeding calipers. It has its own bleeder. Using a piece of tubing and a cup will make things a lot easier and save your paint.

[aznpoopy]

+1 rear pistons are screwed in. you only do the fronts with a clamp. rears you need needle nose pliers or a brake cube socket thinger.

the bleeder nipple is on the left side of the m/c, if you're facing the car. can't miss it.