Z32 Brake problem

[BadMoJo]

Ok, I installed my 30mm Z32 front brakes 2 weeks ago. Brembo rotors slotted and X-drilled, Axxis metal master pads. and SS lines.

And here is the problem. They have been working fine ever since i installed them. Nice pedal feel, lots of stopping power. But today I actually had a chance to hit the twisty back roads and test them out. After a few hard stops (not to many, like 3-4) I started gettign wicked fade, and the pedal was soft. And i could smell the brakes burning! **even saw a cloud of smoke come off of them as i stopped** This didnt even happen with my stock setup. It go so bad that I could have full pedal depression and it didnt lock. I got out and looked everthing over, No leaks, fuid at the same level.

And now that they have cooled down they dont seem to bite as hard as they used to.

What gives? Could the pads just be total crap? I am out of ideas here, help me out.

[/etc/shadow]

What kind of brake fluid do you use? Dot 4 is best for daily driving... dot 3 boils too soon. Dot 5 has a higher temp range but will screw up your brake system.

[adey]

Why does DOT5 fluid "screw up" your brake system? Some explanation would be nice.

[kandyflip445]

Did you clean your new rotors before you put them on? I've heard that when you get new rotors that there is a residue on them from manufacturing...might have contaminated your pads if you didn't clean the rotor with brake cleaner. Oh and the oil from your hands is a contaminant too. Try using latex gloves or other gloves...even though oil from your hands isn't that big of a deal...

[kandyflip445]

DOT 5 is a silicon based and DOT 3 and 4 are mineral based. They DO NOT MIX. DOT 5 will also swell ALL the rubber it comes into contact with...and that rubber will wear, break, etc. That's why you don't use it in your car that was designed for DOT 3.

[BadMoJo]

Using DOT3 HD its a bit better that DOT 4 or so it says.

And the rotors were clean.

[BadMoJo]

I was thinkin I might need to re-bleed them, but that doesnt make sense cuz they were firm before hand. And that doesnt explain the smoke from the hard stop either.

[Jeff240sx]

Did you bed in the pads and break in the rotors? If you don't do it correctly, the pads will glaze over and not work correctly.
Aside from that, smoke is either a fluid leak (since you think you need to bleed, mabey there is a hole in the hose or a bad seal on the calipers). If it's from both sides, it's probably not one of those two, but bad pads.
-Jeff

[tnord]

i will concur. did you have oem pads in there? cause when i had my Z32 and i put new pads on, the next time i went to the track they smoked like a SOB. the oem pads are junk, they fade like a bastard. i'd try bleeding first, if there aren't any air bubbles in the system, then it's most likely the pads.

DOT3 and DOT4 are of same practicality for daily use, but 4 has higher boiling points, and is most likely more expensive, other than that, i don't know any downsides. oh yeah, dot3 and dot4 WILL mix. dot5 like the other dude said, is silicone based and won't mix well. there's something about what happens when water is introduced to the fluid, but i can't remember, look it up.

[BadMoJo]

how long does it take to set the pads and rotors? I think i put about 300 miles on them before i really got on it.

And I dont think its a fluid leak cuz i cant find it and i have not lost and fluid.

Has anyone heard much about the Axxis pads? I have been told they were not that great. But still, I expect better than what they are doing now.

Maybe this weekend I will check the pads out. Can I easily tell if they are glazed?

[kanekz]

Well I have heard that when using the stock brake master cylinder, it can't handle the Z's 4 piston calipers as well as the crapy stock ones. This does't really sound like you situation though. When my friend installed his 30mm z32 brakes, he had very little pedal feel and it was very soft. He took it to a pro and seem that the stock master cylinder was no good. When you are at a complete stop and on the brake pedal, does it gradually sink down? If not, this is probably not the case. When I get my Z32 30mm brakes soon, I am going to change the stock master cylinder to a Z32 one just to be on the good side.

[tnord]

i'm not saying you lost brake fluid, that wouldn't really affect pedal feel i don't think. what might have happened is you boiled your fluid, so now there is air bubbles in the system. or when you refilled your fluid one of the bleeders wasn't fully closed, then you tightened it and inbetween got some air in there, i dunno.

with 300 miles they shouldn't be glazed. go drive it now and see how it feels. if it's still mushy -- brake fluid. if it feels fine now --pads.

[BadMoJo]

its not to mushy now, it just doesnt seem to grab as hard as it did before.

and as far as boiling fluid, i dont think that could be the case, I mean, its new fluid and i wasnt even on it that hard for that long. Thats what makes me think its the pad. I just wanna for sure so i dont buy new pads and have them do the same thing.

[adey]

It doesn't matter if the fluid is new or not; you could still quite easily have boiled it if it wasn't a high quality dot 3 or 4. Granted, it doesn't sound like you really got up to temp to boil them, but it's a possibility.

From what you've said, I can imagine it being glazed pads from improper bedding of the pads/rotors... but how you can tell it's glazed, I have no idea.

[tnord]

if you really wanna know if it's pads or not, bleed the brakes.

1) it'll get out any existing air you have in the system
2) take the car out after you bleed and see how it feels
3) if it's better, then it cost you nothing but time and $1 worth of fluid
4) if that doesn't work, get new pads. although i kinda have a hard time accepting that you faded the brakes that much with a car that weighs at least 500lbs less than the car the brakes were intended for.

just thought of something, when you put the new brakes on, you did a COMPLETE SYSTEM FLUSH right? begining with the RR, then LR, then FR, then FL? maybe you got some poopy fluid still in the system and it boiled, i dunno. you're not going to find a DEFINITE answer from anybody here, you're going to have to try something yourself to figure it out.

[kandyflip445]

Originally posted by tnord
i will concur. did you have oem pads in there? cause when i had my Z32 and i put new pads on, the next time i went to the track they smoked like a SOB. the oem pads are junk, they fade like a bastard. i'd try bleeding first, if there aren't any air bubbles in the system, then it's most likely the pads.

DOT3 and DOT4 are of same practicality for daily use, but 4 has higher boiling points, and is most likely more expensive, other than that, i don't know any downsides. oh yeah, dot3 and dot4 WILL mix. dot5 like the other dude said, is silicone based and won't mix well. there's something about what happens when water is introduced to the fluid, but i can't remember, look it up.

Yes DOT3 and 4 will mix. They both, being mineral based, are hygroscopic. Which means that if you leave them in an open container then they will PULL the moisture out of the air. That's why you won't run out of fluid if you leave the container open and let it sit. BUT you don't want to do this because when water is in the fluid it lowers the boiling point of it(less temp to boil). DOT3 and 4 are a amber color and DOT5 is a purpleish color.

[kandyflip445]

Oh...if you wanna see if there is any air in the system without bleeding you can perform a Air Entrapment Test.

1) Have two ppl.
2) Check your fluid and refill. Replace the cover loosely.
3) Have one person pump the brake 20-30 times rapidly and hold down.
4) Remove the cover and have that person release the pedal.
5) Look for geyser or squirt in the MC when the pedal is released.

The rapid pumping of the pedal compresses the air in the system. When the pedal is released the air pushes the fluid back through the lines, causing a geyser/squirt.

External Leak Test

Use if pedal is low, the BRAKE lamp is on, and if the reservoir fluid level is low or empty.

1) Fill the MC to the proper level and bleed brakes.
2) Press the brake pedal several times; the pedal will go to the floor if the system is leaking.
3) Check to see if the fluid level is dropping with each pedal stroke.

If the MC is losing fluid there is a possible external fluid leak.
4) Check ALL possible leak points. Repair.
5) Bleed brakes. If you didn't find the leak then inspect the wheel cylinders or the caliper pistons.

Also check for a leak where the MC and brake booster meet. If there is more than a little seepage then repair it.

I think you just boiled your fluid though. You can buy tools to see the water content in you fluid. Go check napa or something. Or just put DOT4 in. Try to look up the boiling point of different brands and compare. Just don't use DOT5. I saw a car parked at Wal-mart and there was a BIG puddle of fluid under the front drivers side wheel. It was amber and purple but the colors were not mixed. It turns out the person put DOT5 in their system and it ruined a seal.

[kandyflip445]

Oops...just re-read your post. Says you didn't lose any fluid... Oh well.

[Dousan_PG]

if you want it to grab harder go 90 NA z32 5-speed Brake Master Cylinder. response is sharper. i like it with the stock MC. mushy but more pressure more braking. i dont want it super responsive right now. maybe later.

i used DOT 4 fluid as well. good stuff. i would never go DOT5. you need to bleed tehsystem more frequently (regularly) as well iirc.

[uuninja]

My experience with Axiss metal masters and 300zx brakes, I faded the hell out of them. Metal masters are not true racing pads and don't really need to be bedded (hence they come with no bedding instructions like all "race pads" I have ever purchased) I have found they fade quickly under hard breaking and it gets progressively worse as they heat up. I found this on a road course braking at speeds in excess of 100 mph. Your results will vary depending on you driving style and driving environment.

[BadMoJo]

Thanks for all the help tips guys. I will check it out this weekend if its not raining and let you know what I find.

[Jeff240sx]

A lot of people do not suggest replacing the MC with a z32 MC, because of the brake bias. I think that idiots have a mushy pedal, due to improper bleeding during the install and air getting in, or bad fluid mixing with new fluid from not bleeding the system. Everyone that has ever been in my car mentions how firm and responsive my brakes are.
The z32 MC swap should only be done on a car with a 4 wheel brake swap, because the z32 MC will give too much bias on the stock rear brakes, and spin out the car. That is the popular thought on FA right now.
BadMoJo... didn't I suggest EBC pads? Anyway, I hope that it's the fluid or bleeding so you don't have to buy new pads again. It really does suck bieng broke.
-Jeff

[tnord]

EBC?? do you use those jeff? i've been told by a couple sources that they are junk? what's your opinion of them?

i personally run Hawk's and am satisfied with their performance, especially for $44

[Jeff240sx]

Originally posted by tnord
EBC?? do you use those jeff? i've been told by a couple sources that they are junk? what's your opinion of them?

i personally run Hawk's and am satisfied with their performance, especially for $44

Damnit man. $44. My Hawk pads (which I HATE!) cost me like $60.
I used to have EBC and loved them, until I had to replace them, and you and DSC led me to Hawk.
The EBC have changed a lot in the past couple years. I used the greenstuff, and it was the greatest brakeing ever. They have a .46 coefficient of friction (damn near unheard of) and gripped like hell. They were practically dustfree, and lasted me 14,000 miles of streetraces and speeding (in an auto, it's hard to be kind to your pads). I have nothing but good things to say about EBC. Once my Hawk crap wears out, I'm going back to the Greens. The Hawk pads are dusty, noisy, and don't have the bite I'm used to. If I HAD to pick something to complain about the EBC pads for, it would be that they smelled like tunafish during the install.
-Jeff

[tnord]

which hawk pads are you using?

[uuninja]

I am curious as well I have used both EBC Green and Hawk Blacks. As far as bite, fade and over all wear I have to say advantage Hawk. Though I do have to say that the Hawk's were much harder on my rotors than the EBC's.

[tnord]

Hawk Black???

i know there are Hawk Blues, but do you mean the HP+'s?? cause i have they HPS (they are black) and aren't too bad on the rotors.

[Jeff240sx]

I am running Hawk HP. They should be the most gentle on my rotors, but they suck IMO. I want my EBCs back.
-Jeff

[bbp]

I have used Hawk pads in my cars for years. The blues are definately harsh for street use but their HP+ or HPS are great pads!

BTW: brake fluid can be any color the manufactuer decides to color it. Don't worry about what color it is. The different colors are helpful when flushing a system. If you have golden color fluid, it is easy to tell whne it has been replaced when the new color starts to flow into you bleeder bottle.

[C-Kwik]

If you see smoke from the calipers, it's the pads outgassing. The fade you felt was from this gas creating a boundary layer between the pad and the rotor which makes the brakes much less effective. Unless you were stopping from high speeds repeatedly in rapid succession, the brakes should not fade. If it was just braking as you enter a turn, I highly doubt it's something the system can't handle. I suspect you may have a piston in the caliper that is seized. This would hold the pad against the rotor and eventually over heat. You may need to rebuild the caliper.