300zx F&R caliper swap after install help

[silvia_s14]

i just did a full front and rear caliper swap on my 95 240sx with abs. installed the calipers, used stock 300zx lines and a 300zx bmc.
when i go to bleed the calipers from driver rear, pass rear, pass front, driver front i get a solid pedal feel. but once i hit the street and make my first stop my pedal goes real soft all the way to the ground. almost like i have no brakes.

please help. i tried bleeding with negative cable off. i hear something bout bleeding abs module but havnt tried that yet. kinda scared to touch that lol. thanks


*UPDATE*
so after 3 bottles of brake fluid and hours of head scratching thinking WTF!! :faint: is wrong with this swap, i found the problem. i had thee master cylinders that were all messed up. one was stuck, one was leaking fluid, and the other was leaking thru one of the brake line screws. so i fixed the threads on the master with the screw leak and connected it back up and pressure bleed it. damn the breaks breaks feel amazing!!!! thanks for everyones help :bowdown: . i picked at the car when ever i had time, sorry for the late update but its finally over.

[herbieS13]

got the front calipers on the right side? i made that mistake once did the exact same thing

[Giebs]

got the front calipers on the right side? i made that mistake once did the exact same thing

to check that, the bleeder screw must be towards the top of the caliper.

[hulkster_s13]

Do you have the z32 booster

[Chrischeezer]

probably a big air bubble stuck in the system. Its common when pulling everything apart like that.

bleed bleed bleed...

[silvia_s14]

to check that, the bleeder screw must be towards the top of the caliper.

yup, checked they are on top.
Do you have the z32 booster

nope im am not running run right now. should i tho?
probably a big air bubble stuck in the system. Its common when pulling everything apart like that.

bleed bleed bleed...

i have bleed these brakes so many times. i gone thru a big and small bottle of brake fluid lol

thanks for the replys guys keep them coming :hsdance:

[1quk240]

the little valve thats between Intake manifold/brake booster could be bad. no real way to know, only to change it.

[silvia_s14]

the little valve thats between Intake manifold/brake booster could be bad. no real way to know, only to change it.

Are u talking about the. Egr? That's what I was thinking too

[stinky_180]

EGR effecting braking? I think not! The valve in the vacuum line going to the brake booster is a check valve. It is a 'one way' valve so that you wont push air back into the vacuum line when pushing on the brake.

Definitely sounds like your system needs more bleeding.

[silvia_s14]

Lol that was the only valve I could remember. I know which one tho. I try n swap it out I guess give that a try n yes I will keep on trying to bleed. Just to make sure in what order do I bleed n do I need to unplug neg cable n bleed the abs? I researched a little n found that info

[silvia_s14]

Did some more bleeding today. Did it another four timez bleed drive nothing bleed drive still nothing. How can u tell if booster is working?

[Shadowhunter]

Did you bench bleed the master cylinder? Is the master new and if not how do you know that it is good?

[Def]

You have air in the system.

A bad booster, check valve to the booster or anything involving the booster will make the pedal HARD - not soft.

A bad master cylinder could potentially cause it as well.


Engage ABS a few times on the street to see if that gets air bubbles out of the module, but it honestly sounds like you don't know how to bleed brakes (no offense, but that's what I'm thinking reading this).

[nismolvr]

Assuming the MBC is good , Bench bleed the Master cylinder first. Then buy a piece of clear tubing about the same size of reg vacuum hose.Start to bleed your rear calipers first from RR.LR,RF and last LF. put your 10mm box end on bleeder fitting and then put clear hose on bleeder fitting make sure its tight if you have to use a zip tie do it. take the other end of hose to a plastic clear water bottle.Bleed away and now you can see all the air being expelled from calipers. Make sure your assistant does not release the brake pedal while bleeder fitting is open. Good luck...

[Dustxking]

Do you have the z32 booster

This would help for sure!

[mendozasport]

you do not need the z32 booster........ it is exactly the same as a s14 auto booster and the same as abs equipped s14, don't even spend money on that
your abs unit is full of air, you have pushed air in to it bleeding
first tell us if your bleeding properly
this is how i have done it with good results since i was 14 and had my first car
grab a friend and bribe him to sit like a dumb ass pumping a brake pedal
if the car is running brake pedal gets easier to push the first fue times
but not necessary, if you have the car running remove the abs fuse
fill reservoir and keep cover of, have you friend pump the brake pedal rhythmically and watch the bottle to see movement , if it spits out like a gassier you have a bad master cylinder if not continue to cover
go to the furthest wheel which is the passenger side rear wheel
( here are things i do i normally raise the rear of the car as high as it can be remove both wheels connect the tubing and have ever thing ready before i start , not sure if it is possible for you but i have jack stands that place the rear calipers level with brake master cylinder) have your friend keep the pedal down until you release the liquid and have tighten the bleeder again have him pump again about 6 full strokes and bleed again do this 3 times then move on to the drivers side
check the fluid and be sure its full before you begin
for the front i normally remove both wheels and do the same
passenger side the drivers,

recently i built a jig with and empty cylinder , i connect a refrigeration vacuum pump and it has a port with a close valve that i connect a Tri-y hose set up and while the pump creates a negative pressure in the tank i open the valve and feed fluid through the MC bottle until i see clear fluid through the rear tube

[silvia_s14]

You have air in the system.

A bad booster, check valve to the booster or anything involving the booster will make the pedal HARD - not soft.

A bad master cylinder could potentially cause it as well.


Engage ABS a few times on the street to see if that gets air bubbles out of the module, but it honestly sounds like you don't know how to bleed brakes (no offense, but that's what I'm thinking reading this).
Nno offense taken at all. I'm starting to think I don't lol. I started at both ends rr, rl . I start. With car not on I have bro press n hold brake pedal, I open then close it then tell him to let go n we repeat it over again. Does car have to be on with abs fuse out?

Assuming the MBC is good , Bench bleed the Master cylinder first. Then buy a piece of clear tubing about the same size of reg vacuum hose.Start to bleed your rear calipers first from RR.LR,RF and last LF. put your 10mm box end on bleeder fitting and then put clear hose on bleeder fitting make sure its tight if you have to use a zip tie do it. take the other end of hose to a plastic clear water bottle.Bleed away and now you can see all the air being expelled from calipers. Make sure your assistant does not release the brake pedal while bleeder fitting is open. Good luck...
I never benched bleed iit but have heard bout it. Not sure how to but will look it up thanks. I've tried 3 master cylinder n all do the same. Being all used from a working 300zx. I still have them.thanks

you do not need the z32 booster........ it is exactly the same as a s14 auto booster and the same as abs equipped s14, don't even spend money on that
your abs unit is full of air, you have pushed air in to it bleeding
first tell us if your bleeding properly
this is how i have done it with good results since i was 14 and had my first car
grab a friend and bribe him to sit like a dumb ass pumping a brake pedal
if the car is running brake pedal gets easier to push the first fue times
but not necessary, if you have the car running remove the abs fuse
fill reservoir and keep cover of, have you friend pump the brake pedal rhythmically and watch the bottle to see movement , if it spits out like a gassier you have a bad master cylinder if not continue to cover
go to the furthest wheel which is the passenger side rear wheel
( here are things i do i normally raise the rear of the car as high as it can be remove both wheels connect the tubing and have ever thing ready before i start , not sure if it is possible for you but i have jack stands that place the rear calipers level with brake master cylinder) have your friend keep the pedal down until you release the liquid and have tighten the bleeder again have him pump again about 6 full strokes and bleed again do this 3 times then move on to the drivers side
check the fluid and be sure its full before you begin
for the front i normally remove both wheels and do the same
passenger side the drivers,

recently i built a jig with and empty cylinder , i connect a refrigeration vacuum pump and it has a port with a close valve that i connect a Tri-y hose set up and while the pump creates a negative pressure in the tank i open the valve and feed fluid through the MC bottle until i see clear fluid through the rear tubethank u too. Iwill keep on trying till I get it lol. As soon as I do ill update this asap. Thanks a lot guys