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Discussion Starter #1
Sorry this will be a bit long I think.

I bought my Stoptech front big brake kit around June of last year. Its the standard 355x32 slotted rotor and simple ST40 4 piston calipers. It came with Stoptech pads which were installed. At the time of installation new Euro oem rotors were installed in the rear along with matching stoptech pads. I'd always wanted a big brake kit and was eagerly waiting installation.

A good friend of mine helped with the installation. We've done brakes on our cars several times and were perfectly comfortable with the install. Everything went smoothly and I expected a nice big change in the brake system.....

Which never came... The kit looked cool but didnt REALLY make a huge difference. From high speed there was some degree of better stopping force, but nothing huge. Perhaps my expectations were too great. The pedal didnt really get any firmer even though we did several bleeds, even using rubber mallets to lightly tap the calipers to get all residual air bubbles out. Then the real issues began.

At some point, I dont remember when because it was so long ago, I started noticing a vibration in the wheel when braking. I took the car and did the brake bedding procedure outlined in the instructions and on Zeckhausens website. It seemed to help for a short while, but the vibration came back in a few days.

I decided it was the pads and ordered a new set of Performance Friction Z rated street pads front and rear. Upon removal of the old pads, I found them to be glazed quite a lot. I did no real heavy braking at all, a few single stops from say 130-70 were it. This was done on the highway with lots of travel afterwards without stopping. The brake shudder seemed to go away for a bit, but came back very quickly. The hotter the rotors get, the worse the vibration gets. I tried contacting who I purchased it from who was relatively helpful, but because I took too long to say anything, about 4 months and 3k miles, there really wasnt much they could do about it. I dont want to name them because its not really their fault and I dont blame anything they did in regards to my results.

Im a bit tight on money at the moment as we're trying to buy a home so I dont want to blow money for no reason. From what I've read and what I've been told, there is a good chance my rotors are screwed completely despite them having virtually no wear on them. The formation of cementite is quite possible though I dont think I've heated the rotors to the point where this could happen. I recognize that I probably waited too long to do the bed in procedure, about 200 miles, but I've never bedded any other brakes before. Only pads I ever bedded were track pads on my E46 M3. Every other time I changed pads/rotors I simply drove at a normal pace without using the brakes heavily while the components wore into eachother. This was repeated with several different pad types on both new and old rotors without EVER having any type of brake vibration.

I've considered taking my rotors and having one of the machinists at our company make some type of fixture to hold the rotor by the friction ring and shave the tiniest amount of material off to reveal a fresh surface and then immediately bed the brakes in. Being a floating rotor I dont trust the hub to hold true in a lathe under stress of cutting. The other option would be to buy aggressive race pads and use them in light driving without heating them to operating temperature to clean and scrub the rotor surface. I dont really want to do this because Im not going to be going to the track any time soon and that $300 could go towards other more usefull things. Option 3 is to simply buy new friction rings at a price of $260 a pop. What is the chance that I indeed got a bad rotor, or hub and I've now blown another $500 on something that will not fix the problem. New rotors and hubs are $1000 a pair.

Im at a loss as to what to do, my dad has always been uber against anything aftermarket and way back when I had an M3, he claimed I destroyed the car by putting aftermarket springs on it. Many years later...I fear Im starting to agree with him. I drove his car the other day and was so happy to hit the brakes and be greeted with......nothing! It just stops, no shimmy, no noise, just a nice smooth stop. I dont drive my M5 every day and when I do, I have been taking it easy with it but Its getting more and more aggravating to drive the car with this damn shudder. I want it gone...is this possible without buying new rotors? What does the immense knowledgebase of the M5 board think? Would any of you track junkies who maybe have a set of pads on their last legs be willing to accept a small fee from me to "borrow" the pads to clean the rotors? Or do I just bite the bullet and get new rotors?

Cliffnotes version-- 4k relatively light miles on stoptech big brake kit on front. Lip on the rotor doesnt even exist yet, but getting very bad vibration under braking which increases intensity with an increase in heat. Car has only 49k miles and bushings were checked before the brakes were installed and determined to be good still. Car had no issue whatsoever with brake shake before install of big brake kit. What to do? :sad1:
 

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Discussion Starter #2
I've been doing a lot of research and I believe what Im going to be doing is ordering a set of hawk blues and use them to clean the rotors. They are by far the cheapest pad and from what I've read they are quite aggressive when cold. I think this will be my best bet. And only $80 more on top of the $100 I was going to give my machinist at work who would most likely have totally killed my rotors with an uneven cut. Im still open to opinions of the forum, but I think this is what I will do.
 

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On the super cheap, scrub them with steel wool. Next cheapest thing is to get a brake rotor cleaning tool, they usually attach standard drill.

IMO some pads just suck, try something else. I went through several pads on my race bike before I found the ones I like. On the street though they would drive me nuts, so its all a balance.

Good luck
 

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1st - why have the big brakes if you're you weren't even close to the capacity of OEM brakes?

2nd - you can only stop as fast as your tire will allow; which is to say, if you can lock the wheels with the stock brakes, you will only gain heat capacity and modulation. That explains the feeling of equivalent-to-stock "braking force"; well, that and a change in pad type.

3rd - are your calipers on upside down (bleeder at the bottom)? that would account for a spongy pedal

4th - have you pressure-bled the brake system and/or used INPA/GT1 to cycle the ABS valves to release any trapped air?

5th - I'm not sure why one should expect a firmer pedal than stock, though.
 

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Bushings. How were they determined good? How did you tell that the oil was still in the bushing? Sounds like a suspension problem. Certainly if you don't want to waste money do a very complete inspection of your suspension.
 

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Sometimes, an aggressive brake pad can make as much or more difference in brake feel rather than the BBK.

I bought Stoptech brake pads for my Audi A6 and was very disappointed with the feel/bite.

get pads with more bite and it will improve the feel you were expecting from a BBK
 

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I am curious about something? With E34s we were always talking about matching the pad hardness with rotor hardness. For e34 lots of pads and rotor combos not as many for these cars, but does the hardness of the pad still not have to be matched to the rotor?
 

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Not to be a troll, but how about selling your stoptechs and getting Brembos like you should have in the first place. Brembos aren't made in Korea, which is nice.
 

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I am curious about something? With E34s we were always talking about matching the pad hardness with rotor hardness. For e34 lots of pads and rotor combos not as many for these cars, but does the hardness of the pad still not have to be matched to the rotor?


huh?

that sounds like crazy talk.

rotors and pads should be bedded together; but a pad should always be softer than a rotor considering it's made up of small particles bound together with an adhesive binder material.


http://www.stoptech.com/tech_info/wp_bedincontents.shtml
 

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Not to be a troll, but how about selling your stoptechs and getting Brembos like you should have in the first place. Brembos aren't made in Korea, which is nice.


because if you actually want product support that isn't just a con-artist salesman, you go to other companies with much more aftermarket support. Brembo will simply tell you that you've done everything wrong; thus, ruined your brakes and it is imperitive that you spend $5000 on a new kit if you don't want to die.
 

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because if you actually want product support that isn't just a con-artist salesman, you go to other companies with much more aftermarket support. Brembo will simply tell you that you've done everything wrong; thus, ruined your brakes and it is imperitive that you spend $5000 on a new kit if you don't want to die.
yes that's true, I've dealt with Brembo before and they are of zero help but they make good products which fit right the first time and are reliable, in my experience anyway.
 

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I am content with the choice that I use. If you are curious go to road fly and browse the E34 forum lots of proven good combos lots of proven bad combos. Pads are softer, but not all pads are the same softness. Bedding brakes does create there hardness, but depending on the mix some steel gets harder than others.

Never seen or heard of a car that seems to eat rotors but the pads seem good. Try econo rotors with a ceramic pad on a ford escort.
 

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because if you actually want product support that isn't just a con-artist salesman, you go to other companies with much more aftermarket support. Brembo will simply tell you that you've done everything wrong; thus, ruined your brakes and it is imperitive that you spend $5000 on a new kit if you don't want to die.
Actually Matt, it was $6000.
 

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where are you feeling the vibration, in the brake pedal or the steering wheel.

steering wheel= worn suspension component, probably thrust arm bushings.

brake pedal= warped/deposited rotors etc.
 

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I recently installed the ST60 and it took 2 bleeding attempts to get a good pedal (using the sequence described in the fitting manual) the pedal is alot firmer than before the installation and is a worthy upgrade in itself.The bite from cold could be better though,and I also might try some different pads soon.
 

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If your feeling the viabration when you brake then your discs are warped.

I have a Tarox 12 pot bbk on mine and i had exactly the same problem as you seem to be having, then i done a track day and it absolutley killed my discs. I just took mine to an engineering place and got them skimmed. Job done, been fine ever since, better than they ever was in fact. I think sometimes the bedding in process may cause mor damage than good.
 

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If your feeling the viabration when you brake then your discs are warped.
Warped discs don't happen that often, usually uneven pad deposits. And on our cars, worn out thrust bushings are notorious for brake vibration, moreso with light braking.

I just took mine to an engineering place and got them skimmed. Job done, been fine ever since, better than they ever was in fact. I think sometimes the bedding in process may cause mor damage than good.
How much meat is on the ST rotors? The stock ones have enough for 1 turning, and then it is time for new rotors.

To the OP, the Hawk pads will cure any imperfections within a week. They are very abrasive until up to operating temps, which you will not see in ordinary street driving. After a week or so, switch back to stock to see what happens.

FWIW, I have the same front setup (pistons may be slightly different size as no rear BBK), with Ax Ults and never had a problem. So if you cut the discs, I would put in different street pads.

Regards,
Jerry
 

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Warped discs don't happen that often, usually uneven pad deposits. And on our cars, worn out thrust bushings are notorious for brake vibration, moreso with light braking./quote]
+1

vented rotors usually crack over warping when exposed to extreme heat or uneven heating/cooling. An easy way to check is to spin the disks on the car and measure the z-plane "warp" with a dial caliper. Check both sides of the disk and it'll help figure out a) if it is for sure a brake issue b) if you have deposits where/how big they are.

Did you by chance brake really hard to a stop and then sit on the brakes, say 80-0 at a red light? this type of thing creates a lot of heat build-up and then leaving the pads against the hot rotors will often create deposits
 

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Discussion Starter #20
Ok I thought I'd give an update on my situation. Received the hawk blue pads and installed them. Ran them through normal street driving for 2 days. Initially the vibration was amazingly bad. But the more i drove, doing occasional hard braking without getting the brakes too hot, it started to go away. The amount of dust, probably also combined with a large amount of rotor dust, was also very heavy in just two days.

Anyway, after the two days there was no vibration left. Put the Performance Friction Z rated pads back in and headed straight for the bed in road. I paid particular attention to the instructions and followed them to a T. I think one of my mistakes previously was that I didnt really pay attention to the 60mph mark, usually it ended up being 75-80 to a near stop. Also, instead of doing an 8-9 power stop I just slammed on the brakes as hard as I could engaging ABS. This time, exactly to 60, with nice even brake application WITHOUT any abs application. I could feel the brakes getting a little soft but as they say its normal. Did 10 stops, drove 20 minutes without stopping at 80mph and did another 10 60-5mph stops and the car is perfectly smooth again. No more vibration, no more anything. Back in love with my car! Probably in the next few weeks I'll do another brake bleed to see if I can firm up the pedal a bit more.

So yes, you can fix 4000 miles of bad deposits on your rotors with the magical hawk blues. :thumbsup::thumbsup:
 
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