jokerswld34

hey guys,

so i have been experiencing some very frustrating, and expensive, brake problems as of late. For some reason, i have effectively warped 4 pairs of front rotors, 3 of which were MB OEM rotors installed at the dealer. The rotors are now warping about every week or so, appearing to warp immediately following any panic braking, hard stopping, wet driving or 1000 miles driving. I am using factory pads and have fresh brake fluid, performed at the dealer.

The car has been into the dealer every week now for the last month or so for brake pulse and steering wheel shimmy complaints. Dealer did pressure test of the system, inspected caliper function, and visually inspected the front suspension components. The car has been aligned and checked/measured for bends in suspension components and frame. I have brand new tires on, with proper pressure, new shocks/struts and springs, and have had various front end components replaced over the life of the car (lower control arms, bushings, strut bearings, sway bar and bushings, tie rod ends)

When new brakes are installed, car brakes smooth and even for a little while and then the steering shimmy occurs after about 1000 miles; especially after any brake pressure above 25%. I have completed the brake bed-in procedure as per Stoptech which appears to have warped the rotors even more. the rotors are also not getting shiny. Once the rotors start to pulse and shutter, i notice a slight knocking sound from the front end under braking, especially over uneven pavement. I am at a loss as the dealer (which has been very accommodating) continues to have no answer as to why I keep warping rotors. I don't even want to use the brakes hard because I am afraid the shutter/shimmy/pulse will continue to get worse (but ive used the brakes hard in the past with no issues whatsoever). moreover, im not sure the dealer will warranty the rotors any more as they've already warrantied 2 sets.

What should I look into as a potential cause? i have just recently performed a major service on the car (oil change and MB filter, tranny fluid flush, rear diff fluid flush, Thermostat replacement and MB coolant flush, brake fluid flush, new tires, new brakes, alignment, coil packs, spark plugs) so i'm hoping i don't have to put any further money into the car. any help would be greatly appreciated since I have searched this forum, the internet, talked to indy mechanics as well as the dealer, and altered my driving style all to no avail. if you need more info to put forth a suggestion, please don't hesitate to ask. thanks so much in advance!

acr2001

All this and you haven't replaced the pads yet?! That should have been your first suspect.

Glyn M Ruck

New rotors & pads OE - Bed in immediately new using Stoptech procedure. Never wash the wheels with hot brakes.

Have you tried removing your spacers & running standard wheels?

jokerswld34

pads have been replaced each time new rotors were put on. I have used OEM MB pads for most of the cars life, but have tried EBC redstuff recently as well...I don't think the pad is the culprit here. but how could an oem pad do so much quick damage to the rotor even when driving easy, braking longer, and "properly" bedding them in?

Also, I have not tried taking the brabus spacers off because i dont think the front wheels will clear the sport brake kit. However, i have run my car with these wheels on for 2 years straight with no braking problems until recently so im assuming something has failed to cause these symptoms. I do have a slight bend in the lip of one, but my SA said its not bad enough to cause any problems aside from some vibration at speed (which i dont feel). could that be a factor in such quick rotor warping?

could a bad control arm bushing be an option or perhaps a failing tie rod? the dealer says everything looks and feels tight but i feel a knocking under braking and a loud buzzing noise when braking.

acr2001

You mentioned that the rotors don't show the right color - can you take a picture?
Is it possible that the pads are not making full contact with the rotors for some reason?

I would suggest you swap out your wheels (and remove the spacers) with the new rotors and wait to see if they warp again. How friendly are you with your dealer? Maybe they can loan you a set of used wheels? You have to remember that your wheel and spacer are applying the force to hold down the brake rotor since it is a 'floating rotor'. If that force isn't being applied evenly it might explain the warping.

If the pad is only touching the rotor at one edge it will of course overheat since all of the breaking force is being applied to one small area.

I know your problem is different, but I had this problem when I swapped pads without changing rotors (my rotors were worn at an angle) but I realized and reinstalled the original pads before doing any damage.

jokerswld34

Yes i can try to take a picture tomorrow in the daylight. for some reason the rotors are not showing the shiny, purplish color they used to after proper bedding and wear. it almost seems to be scraping across the rotor so the pad deposit on the rotor does not seem consistent. have no idea why though if nothing is broken???

i have my factory wheels, just with bald tires so that is an option. however, i cant see how swapping the wheels would change the warping considering ive used my current rims for more time than i did my OEMs with no braking problems. but i can see your point about the pressure and force. could a bad hub be a possibility? lugnut issue?

hopefully when i get some pics youll see that the pads don't seem to biting into the rotor much at all, or at least leaving a mark that they are. i remember doing bed ins in the past with this car and after a few 60-10s the rotors would be glazed, shiny and purplish and then would cool to the desired finish. not sure why i cant replicate it...

maybe i should put my slightly used pair of ebc redstuff on and see what happens?

acr2001

From what you're saying I don't think any brand of rotors and / or pads will fix this problem. The issue is with the alignment of your calipers / hub somehow causing the rotors / pads not to align properly, so you only get partial contact. Pics might help me prove that theory, so I'll check back tomorrow.

What's really throwing me is that you're getting this problem on both sides. When did it first occur? Was it the first time you changed your pads and rotors since getting those wheels and spacers?

jokerswld34

so are you thinking im having a braking system issue not a suspension problem? how can i decipher the alignment issue of my calipers and what may be out of spec? from what the dealer tells me, everything measured out fine. but the partial contact theory seems fitting at the moment. its weird tho bc when i have the new rotors and pads, the car drives perfectly smooth and seems to brake normally, until i use them hard or do the bed-in procedure.

this is not the first time ive replaced brakes with these wheels on. ive replaced them a few times since, having the sport brakes requires front brake replacement quite often. from memory, i never had any problems bedding in or warping rotors with either set of wheels until a couple months ago when i started warping rotors every few weeks. could any suspension component be a factor of this or do i need to entertain a new braking system? the dealer thought the additional weight and size of the wheels might require me to upgrade to a larger caliper and rotor size, but once again, i wasn't having this much trouble up until recently so i just cant believe my brabus rims would be the cause. however, i have no idea why both sides appear to be doing the same thing; except it feels to me that the driver side front is the problem area

acr2001

I'm really not sure what else to tell you. Unless your dealer is above the norm, they can't be trusted to diagnose complex things like this - they are clueless. Maybe you should find an independent mechanic to have take a look.

Glyn M Ruck

Has anyone done a proper run out check on the troublesome rotors? This is not a suspension/alignment etc. problem. It's a rotor, pad, hub, wheel bearing, caliper or a wheel/spacer/lug bolt torque, problem.

How do you know the rotors are warped? Can you see high spots?

RedG

I'd be willing to bet no one has checked the hub or bearing.

jokerswld34

im not sure what the dealer performed the last 2 times they replaced the rotors, but the did indicate the rotors were warped. as per the current set, no run out check has been done. im not sure what to look for to concur the rotors are warped; but i can say from how they feel that they seem warped. i get a light shimmy under light braking, a pulsing when coming to a complete stop, a shutter under heavy braking with slight pulling to either side, a knocking sound and steering wobble under braking at any pressure at highway speeds. all symptoms were exacerbated after the bed in procedure. should i try a second bed in? im so frustrated and confused right now...

im taking it back to the dealer this upcoming week for a recheck but im really trying to pinpoint some areas for the tech to look at bc each time he has inspected, i get that everything is ok and a "take it easy on them" (which i have been).

jokerswld34

youre probably right, but i did ask about the bearings and my SA said they were not loose. to me, if my suspension components aren't the cause, then it seems like a bad bearing (however im not getting noise), a bad hub which is not aligning the wheel properly, or a caliper alignment issue as has been introduced in the thread. still though, wouldn't i be experiencing a bias to one side if a bearing went bad or a hub?

Glyn M Ruck

Tell them to check front wheelbearings, ensure they are not loose. Tell them to check run out properly with a dial gauge.

TemjinX2

i agree with acr, its probably because the pad isn't aligned correctly with the rotor. There was a guy in the other brake thread that had a similar issue as you. He bought new rotors and pads to fix his problem.

He found out later that his old rotors weren't warped, but the pad didn't rear evenly so it made the car act like the rotors were warps because the was uneven material along the rotor.

he said if he just wiped away the excess material and got new pads he could've just reused the rotors.

I doubt its a bearing, because you would hear a ticking sound when you drive the car, especially at low speed with no acceleration.

I drove around with a bad bearing for 6 months, it had no effect on the brakes.

jokerswld34

you may be right on the pad alignment issue rather than it being a bearing. however, the rotors dont feel like pad material is the cause but i could be wrong. ive already had 3 sets of new pads and rotors from MB installed in the last 2 months with exactly the same results. im going to assume the rotors are being damaged, but why exactly is still the mystery.

TemjinX2

try just taking it to a indy shop or diy.

jokerswld34

well i have consulted a couple of indys and they all seem clueless as well. id like to continue working with mb since they have been warrantying the rotors thus far (quite a cost if i was paying out of pocket right now). a diy may be in order but i still have not pinpointed the problem to fix. hopefully mb can give me some more answers this week but im so thankful for everyone's input. i think we've narrowed it down a bit more and hopefully now i can help guide my technician to the right area for inspection. but of course im still open to suggestions and input. ill post pics of the rotors tomorrow and see if that adds anything extra to our theories.

RedG

I'm sorry, I should have clarified. It isn't necessarily that the bearing is bad (certainly a possibility), but the hub mounting surface could also require cleaning. This is the surface the rotor hat (rotor mounting surface) mounts on. I also assume you don't have any other vibrations when driving? Definitely get them inspected for runout via the aforementioned dial indicator. But I'd also suggest having the back of the rotors and the hubs cleaned thoroughly. I'd even suggest you find a shop with a 'on-car' brake lathe. As that machine would account for any potential runout on the car.

jokerswld34

i didn't have any vibrations until yesterday when i noticed the steering shimmy and pulsing. now, i get a slight vibration while cruising, but it is very very slight. the hub surface i believe was cleaned during the first brake installation 2 months ago but i can't say for certain, and mb mentioned they had cleaned something but not sure what. i doubt its been resurfaced so that could be a very good potential. im going to suggest to the dealer to check the runout with the dial, check the hub for uneven surface or damage, inspect the bearings, and check caliper alignment. hopefully by doing this we can start crossing things off the list. also keep in mind, i live in MA so my front end has taken a fair share of pothole, uneven pavement and bump wear...

LILBENZ230

How many miles do you have?

jokerswld34

i have 130k now (i do about 30k a year bc of work travel). i just spoke to my SA after booking a service appt for this afternoon and he explained they had done a runout check with the dial gauge, inspected hub surfaces and bearings and checked for caliper/pad alignment. not sure now where the problem is, but im hoping its nothing too major. any other theories now would be greatly appreciated so i have more info to share with my SA and MB tech. thanks so much again for all the input

acr2001

You've got me. Off the top of my head I have no idea what else to tell you.

Buellwinkle

With that many miles, I would suspect the calipers are sticking and I would have rebuilt the calipers or got new ones, cheap enough. What's likely happening is when the calipers are sticking which is overheating the rotors and warping them.

The other possibility, and this happens only when I got to American Tire, they overtighten the lugs and that warps the rotor. But you would have noticed that right away, not a month later.

jokerswld34

could the calipers be sticking slightly or intermittently and thats why when the techs checked for proper function, they determined the calipers were working correctly? i just took the MB shop foreman out for a ride and he was pretty surprised and confused as to why the rotors keep warping (he has not been involved in the work on my car to this point). unfortunately it is raining hard here so im going to drop the car off tomorrow for a nice day and hopefully some better news. if the caliper is sticking, i think it may be time to upgrade to the stoptech bbk or c55 amg kit. thanks for the additional suggestions. i really really appreciate all the help.