Dream240

I have the 300zx brake upgrade all the way around and I'm running into warped rotors!! I just replaced the rear rotors, which were cheap ebay rotors, with Brembo blanks. The heavy vibration I had at highs speed braking disappeared instantly. So I knew that was the problem. Well, about three days ago my brakes started sqeaking out of nowhere, WTF? I figured they were just dirty, so i washed the car and sprayed down the brakes with the hose. ALOT of black crap came off the wheels and brakes. Squeak was gone. Then yesterday I started to notice the high speed vibration under braking again!! So WTF I warped them already? It's only been a couple weeks!! I broke them in like i was supposed to, easy braking under the first 500 miles. I'm at a loss, the only thing I can think of is maybe my brake bais is screwed up? I have swapped out the MC with the 17/16" Z32 and I have the SS brake lines. What else could be causing this problem? I know it's the rear brakes cause the vibration shakes the whole car and not the steering wheel that much. you can feel it in the steering wheel but only from the car shaking. And it's groans from the rear somewhere when I brake. ANYONE HELP!!! I'M READY TO BLOW MY CAR UP!!!!

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ghostuss

Did you bleed the brakes properly, in specific order, blah blah...? Did you bleed the master cylinder also?

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Dream240

Yes I did. The pedal is fine. very stiff. Too stiff sometimes in fact. I'm figuring it's the pads. I got Axxis ultimates, which are cheaper than all other high performance pads. When I was using Hawk HPS pads I had no problems. So I went ahead and ordered Hawks for the rears. I'm gonna swap them out and have the rear rotors turned to see if that fixes the problem. I've got ultimates on the front too, but I'm gonna swap back in my Hawk pads that I had in there before to see if that helps too.

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XxJaPxOxNeEs23xX

i dont think its the pads cuz if it was the pads it wouldnt vibrate like a warped rotor. i think. but the squeaking is usually from vibration in the pads. not dirt. so wen u wet it it probably just kinda lubricated the back of the pads itself so it ddnt squeak. and is the vibration from your brake pedal or your car. if its the car vibrating while braking its your tires or your alignment.

ledzeppelin240

Fist of all you do not have warped rotors. Buy expensive rotors don't waste your money on that cheap shitthats a number one, and I see you have bremo blanks. Some of those cheap rotors are out of round have thickness variation and are just plain do not have enough metal to them. You have a thickness variation problem. Warped rotors do not affect pedal feel on a floating caliper assembly. Thickness variation is a difference in thickness in the rotor, especially between the vents where there is less metal.

The thickness variation cause the pedal pulsation. I am willing to bet that there is quite the difference in thickness if you were to use a micrometer on them.

The best fix is some good quality pads and some good quality rotors. I guarantee you will see a world of difference. As for the squeaks and noises, coat everything in a silicon lubricant, ie: the back of the pads, contact points, not the friction surface. Check to see if the sliders are sticking which could be overheating the brake system. Lube everything up good.

The pedal pulsation could also be from bearing runout, which causes alot of slack in the system and will create a low pedal. You should look into getting a dial gauge and checking everything for runout, even check your tires which could also give you a shimmy or pulsation.

-chris

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Dream240

Okay so you are saying that Brembos are cheap crap? Since when? I could have sworn that brembo was the best in the business. And if they're not then who is? Which brand do you use, Powerslot? Also The vibration was NOT there when I did the rotor swap initially, it has started the past couple days. I noticed that this morning on my way to work it was worse than this afternoon after work. Maybe the colder temp has something to do with it?

Also I DO have an alignment issue, but it's not major. Also the rotors are not glazed, and I have rebuilt the calipers when I did the rear upgrade. I have also applied plenty of anti squeal to the pads and shims when I installed the brakes. I'm gonna have the rotors checked for warpage and install the hawk pads and go from there. Oh and the alignment is coming up soon.

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XxJaPxOxNeEs23xX

well check your alignment first before you spend any more money on the brakes. and i still dont know is it the car vibrating or the pedal pulsating.

Dream240

The car is vibrating, not the pedal. Also the steering wheel vibrates a little. I'm thinking it's the alignment and the balance too. I wanted to get the pads anyways cause Hawks work really good with blank rotors, and I KNOW they won't squeal on me. Would have went with Project Mu but I couldn't find them for a decent price.

Thanks for the help!! I'll keep you guys posted.

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XxJaPxOxNeEs23xX

yeh for sure its the alignment. it happend to me wen i had this guy i knew that just learned how to do alignment, align my car. everytime i go at highspeed or brake at highspeed the car and steering wheel start shaking.

Dream240

Thanks for the info. I'll check into it and let you know.

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ledzeppelin240

What was meant is I noticed you got good rotors after the cheap ebay ones. Brembo blanks are awesome. English is not something I am that good at... If everything is lubed up and nothing is sticking I would check alignment and balance. Like I said before check your wheels and tires for out of round. Out of balance tires will cause the problem you are having. Do you notice that your tire tread is worn down in some spots? Throw them on a blancer and see if theyare out of balance...

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Dream240

The tires are brand new. And I did check them recently, they're showing fine tread wear. I should mention that I recently swapped in some camber correction arms myself and adjusted the camber myself as best as I could to "0".

I think one side might be off from the other. The alignment is my next move. I've already ordered the hawk pads and I'll check the rotors for warpage BEFORE I replace the pads. Besides I think the Hawk will have less dust than the Ultimates. We'll see....thanks guys for the help.

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ledzeppelin240

Check for lateral runout as well as thickness variation, warpage is not felt on a floating caliper assembly. Not being able to drive and see the car in person makes it hard to completely figure out whats going on. Good luck...

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Dream240

Wait, Z brakes are floating? I thought the 240 brakes were floating and the Z were a fixed setup.

Also in my car I HAVE felt warpage that was confirmed on both setups. Just to let you know.

I've already got the new pads (damn fast shipping) and after some info from another source, I'm really thinking it's the balance and alignment. Checking those this weekend and swapping in the Hawk pads to eliminate the squeak....hate squeaks.... Let you know how it goes.

Thanks alot.

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orion::S14

Z-brakes are FIXED calipers...

Stock calipers (and Q45) are SLIDING calipers...

Maybe he means floating rotor...but that doesn't apply here either...?

- Brian

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XxJaPxOxNeEs23xX

no he meant floating caliper but it hink he thought u had stock ones with brembo blanks?

but anyway,i had a question about zbrakes( offtopic sorry). thers this guy in my auto class and hes telling me his freind that works at motorex says that z brakes arnt as good as stock ones. he said the rears sucks and they dont grab as good as stock ones? is that true or is it his imagination.

SlideStar

They don't work as well if you don't upgrade to the 300zx brake master cylinder at the same time. Otherwise you're pushing bigger brakes with
the same stock cylinder and getting the same or worse brake power.

projectRDM

If the vibration is there when the brakes are not applied, it's not the rotors, simple.

If they are warped, you could be torquing your lugnuts too tight, or when you wash the car the brakes are still hot. It's actually pretty easy to warp a rotor if it's hot enough.

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Dream240

Torquing the lugs too tight? Hmmm....hadn't thought about that. How would that cause them to warp? I tighten them by hand but not using a torque wrench, just the "feel" of how tight it is. My dad has a torque wrench I'm just too lazy to use it.

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Mr. Badlose

There's a chance your wheels aren't on right (even though it may sound dumb).

Torque them to 80 lbs foot. Then go for a short drive, then torque them again to make sure they're not magically loose.

You can't torque them too tight as to make the wheel unstable, you'll just break off a stud. Another thought: maybe your wheels need to be re-balanced?

SlideStar

From what you've said the problem is not with your tires or bolts. And it's not a problem with bleeding the lines either. What it sounds like is most likely the rotors or calipers. Maybe even the shims on the pads or the pads themselves. Can you try putting you old brakes back on?? Let us know when you find out what it is for sure.

XxJaPxOxNeEs23xX

yeh iv heard that u can warp your rotors by tightening the bolt on too tight. also i still think its alignment not the brakes.

Dream240

Okay, here's the results from this weekend.

I got a 4 wheel alignment, made a little bit of difference in the vibration. Then I rebalanced all 4 wheels, used the dynamic balance with stick em' weights. Turns out the balance was waaay off on two of the wheels.

That made a HUGE difference!!! There's still a slight shimmy when I brake I figure the rotors are now warped a little due to the vibration and now need to be turned and I should be good.

Now the pads, that's a whole different story. They squeak like your sister's bed on prom night!!! For the life of me I can't figure out why. I want to say it's bad/worn shims and retaining clips, even though they look fine (can you honestly tell a bad shim?) So What I'm gonna do now is get new shims and replace the pads with the Hawks.

IMO all AXXIS products suck ass. I had Axxis PBRs on my car back when it was stock and I'm running the Ultimates now and I don't like them at all. I should have just stayed with what worked. The hawks are really good and don't squeak!!! Moderate dust but I've got that now so who cares? Besides I clean my car like every other day so no worries.

Oh and for the over-torqueing theory, every mechanic I talked to (4 guys) laughed, literally. They say that's the same as saying your shorted out cigarette lighter makes you burn oil, retared really. Just thought I'd relay the message and clear any confusion. They say that when you have a shimmy when you brake it's the brakes 100% of the time. which is true in my case but the balance and alignment just made it that much more noticeable.

Thanks guys for all the replies.

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ledzeppelin240

Yeah, got confused z-brakes are fixed...Overtightening lug nuts does cause runout in rotors, you compress the metal and its does not come back. The mechanics you talked to were obviously stupid and don't realize theory. Getting water on a rotor when it is hot does nothing to a point, have you ever driven in the rain? They are constantly getting soaked. Don't get the rotors turned you will most likely end up with thickness variation...

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Dream240

okay when you say over tightening like how much? 150 foot lbs? Cause I figure 100 lbs is still good not too tight. Also what exactly is runout? And why would you get it by turning the rotors? i thoguht turning them would make them straight again?

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FRpilot

dammit! now someone tells me after i ordered my axxis ultimates. everyone said axxis ultimates and pbr and pretty good. but i dont want to run them and risk ruining my z32 bremo rotors front and rear rotors that cost $300! where did u get hawks from?

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Dream240

Here's the thing, some guys say Axxis are good, and some say there crap. I one of the crappy guys. They might work good for you. But with my experience with both Axxis and Hawk, I'm going with hawk because of the squeaking issues and the fading. Yeah I had my first fading experience with the Axxis pads the other day. going downhill doing about 75, had to come to a complete stop pretty quick (damn Cali freeways). And by the time I got to 0 mph my pedal felt mushy somewhat. NEVER had that with the hawks and there was a few times where I had to be "johnny on the spot" with the brake pedal.

I checked around and got my pads here:

http://www.ltbmotorsport.com/nissa300zx.html

Pretty cheap and I got the pads in like two days!! No shit!! Really great price and shipping.

The other option for pads would be Project Mu "B-Force" pads. But they run about 80 bucks a set and are hard to find for that price, most places charge about 99 bucks. Good luck with your choice.

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ledzeppelin240

Runout would be lateral. It might look like this when it turns: \ \ to l l to / /. I personally would not get rotors turned, they need the metal, thickness variation comes alot easier with rotors that have been tuned even though they are within specs. The lug nut torque spec is 72-87 lb. ft. So at 100 lb. ft. You are only 13 lb. ft. over, but if you were more metal does give and does not always come back the way it was before. Even 20 over could put runout in brand new rotors...

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Dream240

Okay so what can you do to fix runout? Do you just have to buy new rotors?

How can I fix this problem?

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ledzeppelin240

Yeah replace rotors, but first you should check them with a dial indicator if you can to see if they have runout. It is very hard to say what it might be when I can not drive the car or physically look everything over. But good luck, nice to see the problem is slowly dissapearing with the more things you do.

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