evo_z

OK, I've had my stock brembo rotors machined twice now. The last time was four months ago but now I'm starting to get vibrations again when I brake, not as bad as before, but definitely there. Now I'm thinking of getting two piece rotors but I'm not sure how effectively they'll be in keeping the rotors from warping. I can have the stock ones machined again for $250 (front only) but I dont want to have to keep doing that everytime the rotors warp. What other possible solutions should I look into? Also, why does this keep on happening? TIA!

Oh and another quick q, should I take my chances with ebay rotors? Has anyone tried them yet?

Wheelhaus

iTrader: (2)

Well, here goes. It could be a multitude of things, there's no "this is the problem" answer for you.

You might try different pads, better airflow, etc etc. The rotor itself probably isn't warping, it may be the hat. I read a page on stoptech's whitepages that stated warped rotors are a myth. It's typically too much brake pad deposit or a warped hat.

What type of driving do you do, track events, daily driving, spirited mountain drives, what? What type of equipment are you using, all OEM, anything aftermarket?

First things first. Technique. If you're using your brakes HARD at the track then try changing a few things. One taboo is to stop with your brakes applied. Never do this, as it will cook the pad to the hot rotor. Always use a block, a rock, piece of wood, a wedge, or find a dip in the pavement and let the car roll to a stop so the pads don't touch anything while the car is static.

Second, remove the dust shield against the inner face of the rotor. (You may have to reroute the ABS wire or brake hose).. This shield will retain heat and prevent cooling. you can also look into the OEM control arm brake cooling guides. They won't work wonders, but they do help. Also, I'm not sure if your car has the OEM underbody tray, but it has ducts and guides that help a lot if you've got the control arm ducts as well. Some people take it off because it gets in the way of maintenance, but it's there for a reason.

If you go with aftermarket rotors, you won't need 2pc rotors, but you will definitely want directionally vaned rotors. The vanes act as a squirrel cage fan to pull hot air from the inside to the outside of the rotor to dissipate heat. Our OEM rotors are pillar vaned (or kangaroo paw, whatever you want to call it) which I've heard is better at low speeds, but higher speeds don't cool as well.

Last but not least, check your hubs and bearings. My friend had an M3 and went through 3 sets of Brembo rotors (thinking they were warping) before finding the problem rooted at the hub. Something was warped, bent, or oddly worn and it was causing the rotors to oscillate a little bit when they got hot. It felt fine when new, but once they got hot, the rotors were wearing unevenly because they weren't seated properly. I believe it was the axle shaft... Fixed that, now he can abuse the brakes as hard as he can and there's no worry of "warping" the rotor.

If the pads are "street" pads and you're using them at the track, that may be part of the problem. The weak high temp friction coefficient may need higher pedal pressure to stop the same, which may be overheating your business. Better pads have a better friction coefficient, so they won't bake so hot and glaze over. Better brakes doesn't always mean hotter brakes, so better pads may solve your problem for your driving style.

Wheelhaus

iTrader: (2)

Also, DON'T trust ANY... I repeat, ANY cheap eBay parts for anything critical on your car (especially for brakes). Even if it looks authentic, i wouldn't trust it unless I know it's coming from a 110% trustworthy source. They may work flawlessly, but there's no real promise or trust. Stick with a reputable company. You can buy OEM quality (or better) parts for pretty cheap if you dig around.

evo_z

Thanks for the reply. My car is as stock as it can be. Been using the same pads every since I bought it. I dont do trackdays with the car (I'm kart racing now ^_^) so the brakes are worn from just day-to-day commutes. The first time they machined the rotors, it fixed the problem for about a month so I suspect the guys who did it didnt do a very good job. The second time was with a different dealer and their machining job lasted for 4 months.

One thing I'm suspecting that may have caused it is my tires. You see, I had stock advans up until Oct of 05. I never had any warping issues before then. When I replaced the advans with sumitomos, I went with 245/45/17s instead of the 235s like the stock ones. About a few months after getting the sumi's, I started getting brake vibrations and had warped the rotors. Does this sound logical, the change in tire size caused the rotors to warp over time?

Gary_BremboRT

evo_z,

Maybe I can offer a little more insight to your "warpage" problems.

While it is very possible that your disc may have been warped, Wheelhaus has more than half right when he mentioned it could be due to uneven pad deposits.

- How many miles were on your car before the first time you thought you "warped your discs???
- What pads were you running???
- Had you participated in any track events, or track like driving???

The only proper way to tell the difference between a warped disc, or a disc that has pad deposits is to check the disc itself for runout. Runout is the side to side movement of the disc during rotation and would prove a warped discs. If there is no abnormal sign of runout, then you most likely have uneven pad deposits. While the deposits are usually not visible or significant enough to register as runout, they may be just enough to transfer vibrations through the steering wheel under braking.

Since a lot of times mechanics don't want to take the time to check for runout, they will just assume it is a warped disc and recommend having it machined. While this is a satisfactory "band-aid" for both problems, you still have not found the root of the problem. Not to mention, that when you machine, or resurface the disc, you are removing material and further weakening and increasing the chances to have the same or even more problems in the future. And, since you are now using a disc that has been machine 2 times, it is too late to go back and correctly assess the problem.

My recommendation is to start with a fresh set of discs and pads. Preferably a disc from and Authorized Brembo reseller to avoid and other unexpected problems. Following the proper bed in procedures, and take extra caution when the rotors are hot to help prevent uneven pad buildup. If the "warped' feeling does return, have a trained mechanic check for runout. Once you find the exact cause of the problem, we can then work on other solutions to prevent the actual problem from returning.

Unfortunately since you have a discs that has been machined twice, you may have already exceeded the minimum thickness of the rotor and anything you do from this point would be insignificant in finding the initial problem.

value

iTrader: (1)

Gary here's my 2 cents for what little it is worth. Pad transfer: Is it possible when the EVO pads were decided on they wanted a pad that wouldn't tear up rotors so it was decided to use a 'softer" pad which will allow material like rust, dirt, metal ect to inbead in the pad and cause pad transfer. I read alot of posts about pad transfer but most say to either turn the rotors and get new pads or try the reseat your pads by doing a bunch of high speeds stops which has never worked so well for me? what is the prefered method to get rid of it? I feel a change to a better pad and a runout check which you mentioned and added cooling are key.

Wheelhaus

iTrader: (2)

Ok... you don't do track days, so you're not glowing your rotors or fading the pads or overusing them beyond their limits.. It doesn't seem like you'd need extra cooling since you're likely not pushing the system enough to overheat.

If the pad(s) deposit material on the rotor it is likely building up over time, making it feel like the problem has suddenly reintroduced itself once it's enough to be noticable. Maybe something contaminated a pad(s) so the pad is breaking down and sticking to the rotor.. If each time they've been machined it feels better for longer, you may be wearing past the contamination, but who knows.

I agree with Gary, get a new set of rotors (I'd reccomend genuine OEM parts from a reputable dealer if you don't need anything ultra high performance, check with some of the vendors here for good prices). And get a new set of pads, either a new OEM set or Hawk HPS or something. It's not the cheapest route, but definitely the most effective. Eliminate as many variables as possible. If you're worried about OEM pads causing the problem again, there's lots of other high quality street pads on the market.

evo_z

I think I had about 9000 or so miles before the first time I had the problem. Im using stock pads, same ones that came with the car and I dont track/auto-x it, just day-to-day freeway and street driving. I guess getting new rotors would be the best way to find out what's causing the issue. It could be pad material build-up, the vibrations are somewhat intermittent and arent as bad as the first time. If I do get new rotors, I'm planning on getting slotted ones to help with 'scraping' off old pad material from the pad surface. Now, would it be ok to keep my current pads or should I buy new one? I'd like to stick with a budget if possible.

Wheelhaus

iTrader: (2)

you could keep the pad, but it's also likely the pads are the root of the problem since the material isn't burning off as it normally should.

edit- here ya go:
https://www.evolutionm.net/forums/sh...d.php?t=169029

front slotted rotors and HPS pads for $350 shipped 2nd day air.

I've heard good things about powerslot.

value

iTrader: (1)

This is probably my problem I think. Whenever you wash your car all that rotor rust in my pads.

trinydex

iTrader: (12)

damn someone has been stealing from you... poor you.

as for the tire change, perhaps your new tires can't generate the grip necessary for you to bed your rotors in properly. just beat the car on a regular basis. otherwise you'll get stupid pad deposits.

nothere

iTrader: (23)

do you do any hard braking coming off the freeway? sort of last minute stops from speed?
Then sit at the light waiting for the light to turn green?= pad deposite. pratice doing your stops so you sit at the light with no pedal, coast to a stop the last few feet.

anjapower

iTrader: (18)

seriously...I got all 4 of my rotors resurfaced for 65 bucks.