300zx brake help!!!

[Spiffy240]

Ok so recently I went nuts and installed/swapped the following:

front ichiba hubsrear 300zx hubs w/ ebrake and aluminum uprightslotted/drilled rotorsHPS Hawk pads300zx 30mm aluminum calipers both front and rearrebuild the fronts w/ all new piston rings/seals300zx brake master cylinder and brake boosterSPL brake linesSPL KTS Coilovers

WARNING story ahead scroll to problem if you dont feel like reading

what a mouthful, anyway to the problem...after dialing in the coilovers and bleeding the brake calipers (yes installed w/ bleeder upwards) it was time to take it out for a spin to break in the new pads. They start to break in well when all of a sudden white smoke comes pouring out from the driver side front... not good. Then as im driving back home to take a look at it, the brakes feel like there engaging without me pressing the brake pedal. I have to physically pull the brake pedal towards me so that the brakes dont engage as much. So i then go and look at the caliper and i see that caliper is leaking from the area where the two halves connect and NOT from the caliper pistons. So i decide to take them apart and what do u know, one of the o-rings is missing...

So short story, I need another o-ring thats in between the two halves of the 300zx brakes. Where can I find another oring??? Also, could the issue of the brakes engaging without me pressing the brake pedal be just the issue of the leaking caliper or could there be another issue at hand.

PLEASE HELP if you live close to me or if i ever see you ill buy u a giant COOKIE ThanksAdam

[nightsauce]

i heard that you find those seals (or something of the same size) in the rubber seal pack at autozone. I'd help you but I have no transmission on my car :|

[Spiffy240]

ok, went to ace hardware and got o-rings of the perfect size and it works!!!!brake calipers do not leak.

but the problem of the brakes engaging is still there.this starts to happen once the car is warmed up and has been driving for approx 5-6 minutes. its feels as though the brakes are engaged and it feels as though the car is slowly locking up and about to not move at all.

my friend says it might be that the axel bolt on the ichiba hub are a little too tight, although they are to spec at 105-150 ft/lbs. i believe we set the 1/2" torque wrench to 125 when we installed them.

im saying it could be a vacuum issue with the brake booster. could insufficient or too much vacuum be causing this issue. Especially since this only happens when the car is warmed up. Could too much pressure in the booster along with added heat from the engine cause the booster to have too much pressure thus causing the brakes to stay "engaged."

SOMEONE PLEASE HELP!!!

[duffman1278]

I was on the same boat as you for the brake calipers. I will advice you on one thing, even though you said the o-rings you bought fit perfect, doesn't mean they're meant for this type of use. When I went searching around I ended up finding out that I should be using, iirc Viton o-rings. It's a material that makes up the o-ring which works well with fluids.

[Spiffy240]

thanks for the advice, but the calipers are not leaking w/ the o-rings i used. The o-rings i used from ace are meant for fluid application as well.

so... after spending a day and no result, F-ING NOTHING!!!!really starting to piss me off

i got a vacuum pump and vacuum is fine on the booster and linescaliper doesnt leak

When you first drive the car everything is perfect, brake engages nicely, pedal feels great, stops on a dime, perfect i tell youThen after 5 minutes w/ moderate braking, the brake feel like they are locking up and engaging without depressing the brake pedal. Without pushing the gas pedal, the car does not move even though it is in drive. I AM STUMPED and cannot figure this out. Please Help a fellow Nico Member.

Adam

[duffman1278]

Are you sure you got all the air out of your lines after putting them back together?

When I did my swap I had to bleed the brakes like no other before I finally got them to normal. I was having a similar issue as yours. I ended up using a compressed air brake bleeder system and it sucked the air out like there was no tomorrow but I also went through alot of oil just to get it all out.

[Spiffy240]

ill try bleeding them like hell.

also, i forgot to put the fitting into the brake master cylinder. There is a little piece that goes into the bmc that you have to take out from the old bmc and put it into the center hole. I think that might be effecting the performace and flow of brake fluid.

I will update after i do some of these things.

Thanks for the help duffman

[nightsauce]

did you bench bleed the brake master cylinder....

[nightsauce]

ill try bleeding them like hell.

also, i forgot to put the fitting into the brake master cylinder. There is a little piece that goes into the bmc that you have to take out from the old bmc and put it into the center hole. I think that might be effecting the performace and flow of brake fluid.

I will update after i do some of these things.

Thanks for the help duffman

i never took that out of the old BMC. My old BMC had major problems

ill try bleeding them like hell.

also, i forgot to put the fitting into the brake master cylinder. There is a little piece that goes into the bmc that you have to take out from the old bmc and put it into the center hole. I think that might be effecting the performace and flow of brake fluid.

I will update after i do some of these things.

Thanks for the help duffman

i dont think so...i didnt put that piece in from the old bmc.

[Spiffy240]

how do u bench bleed the brake master cylinder....i think i forgot that step.

never saw a writeup on it or anything specifying to bench bleed the brake master. Also i feel its only the front brakes that are locking up when they heat up.

[nightsauce]

you have to manually pump the rear of the BMC until all the bubbles come out....

heres a video...i used a 3/8 ratchet extension to push it inhttp://www.youtube.com/watch?v=_VMXC2xsy2s

[nightsauce]

any luck? hope it was just bleeding the brake MC that was the problem...i got my transmission up and running now :] kinda excited...

[Spiffy240]

well not really

so i bleed the bmc and the lines again (w/ and w/o a vacuum pump) and everything worked so i took it out and drove it for about 25 minutes and i went a little nuts b/c of the new brakes and coilovers.

Then later on that night, i went to go out with some friends w/ my car because everything worked and i washed and waxed the car really nicely. The problem popped back up......from the time it worked to the time it didnt all i did was tighten down the brake lines connected to the bmc b/c a tiny amount was leaking out. i think its the center brake line connection to the bmc b/c the little black flare fitting is not in the whole. I found something on ebay that connects to the bmc that i think will solve the problem

link to ebay:http://cgi.ebay.com/ebaymotors...ories

[94_240sx]

Oh! You didn't take care of middle fitting. It's very important. I've seen some bad reviews on aftermarket adaptor fitting. Best thing is OEM BMC with middle fitting already pressed in, but if you can't get that one, you can take one out of old s13 BMC or something. Good luck with your fix.

I've heard that you don't need to bench bleed z32 BMC. You just pour brake fluid and air bubbles will come out if you press pedal several times and that should tale care of it. I didn't bench bleed mine and it's been working perfectly.

[nightsauce]

Oh! You didn't take care of middle fitting. It's very important. I've seen some bad reviews on aftermarket adaptor fitting. Best thing is OEM BMC with middle fitting already pressed in, but if you can't get that one, you can take one out of old s13 BMC or something. Good luck with your fix.

I've heard that you don't need to bench bleed z32 BMC. You just pour brake fluid and air bubbles will come out if you press pedal several times and that should tale care of it. I didn't bench bleed mine and it's been working perfectly.

what makes that soooo important?? I didnt put that in and my brakes work just fine. In my s13 brake MC the hard lines wouldnt come off so i just said f**k it and just kept it moving.

[SmithSR]

Oh! You didn't take care of middle fitting. It's very important.

I've heard that you don't need to bench bleed z32 BMC. You just pour brake fluid and air bubbles will come out if you press pedal several times and that should tale care of it. I didn't bench bleed mine and it's been working perfectly.

You should always bench bleed the MC before installing it. By installing it and THEN pouring in fluid and pressing the brake pedal, you are doing the same thing... just not with as much precision. You want the MC to be free of air so you don't introduce air into the system. This stuff should be obvious.

The master cylinder you should have is Nissan Part Number 46010-30P22.Direct bolt in, no issues with the fitting, and it actually works. Gasp!

To the OP I would start with making sure you have the MC i listed, bench bleed, make sure you're using the stock pushrod into the MC. Install and bleed the MC again, using pedal pressure and have a friend run the wrench, starting with the fitting farthest away from the firewall. bleed system at the wheels, test drive.

[Spiffy240]

Thanks for all the help.

For everyones information, it was a bad Brake Booster b/c it was retaining too much vacuum causing to engage without pressing the pedal thus prematurely engaging the brakes.

So for anyone with a similar situation, its the brake booster that was causing it. Im looking for another one or possibly just picking one up from my local auto parts stores.

[numbnuts240]

ace hardware huh? i've been on a wild goose chase for those same rings. they're actually quadra rings, not o-rings (i just learned this today lol). double check that the rings you bought are good for this application. they may be for a fluid application, but not necessarily an automotive brake fluid application. i spoke to a guy in great length earlier about different types of materials and which will stand up to brake fluid. he had the right size and profile that i need, but the material wouldn't stand up to brake fluid. double check those rings, you don't want the fluid to break them down and all of a sudden your brake fluid starts pissing out the seams in your calipers while you're driving. i'm going to look into them since there's an ace hardware not too far, hopefully they check out and those of us rebuilding z/skyline brakes can finally have a solution to this issue.

[Spiffy240]

hopefully someone can find the solution to the whole gasket issue between the calipers and find replacement gaskets for people looking to completely rebuild their 300zx calipers.

IF ANYONE has any insight on this issue, please post and moderators, if the information FINALLY surfaces, could this be stickied???

THANKS

[numbnuts240]

i've found that the three materials which will hold up to automotive brake fluid are

-aflas-viton

i've been calling various places around the country and it seems that the size quad rings we need in the appropriate material is an item that is quite hard to come by. i'm still searching for a viable source.

edit - i may have a lead in louisiana. i'm waiting for a call back. if this pans out, i'll pass on the info and price.

Modified by numbnuts240 at 12:56 PM 9/17/2009
Modified by numbnuts240 at 12:57 PM 9/17/2009

[numbnuts240]

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