Need some guidance in potential reasons for front rotor warp.

Quick background info.

First noticed pulsating when braking around 45+ mph. Suspected it was from rotors. Got the front rotors and pads replaced around 39k miles. Short after noticed the same issue again at 41k miles. Took it to the dealer and confirmed that rotors are warped. They replaced the fronts under warranty. Same issue again happened at 43k miles. Took it to the dealer and confirmed the front rotors were warped again. Dealer stated they can replace the front rotors and pads against under DSA goodwill if I were to get the rear brakes completely done to rule any other issues. The same issue again occurred again around 47k miles and at that time the dealer couldn’t do much. I reached out to MB corporate and basically was told I’m out of luck. Dealer confirmed during all these times there were no issues with suspension or caliper. I took it to a third party mechanic who did a run off on both front hubs and they were within the normal range. I decided then to get a set of VNE rotors and OEM pads around 51k miles hoping for the best. Now I’m having the same issues again around 52k miles. I took it to another mechanic and they weren’t able to find anything wrong either. The latest shop suggested maybe changing out the calipers. One of their Audi customers had a similar issue and problem resolved after a new set of calipers. The Audi customer was lucky was enough to get that all troubleshooted by Audi dealership and Audi engineers.

I’m wondering if anyone else had any similar issues? I don’t track my car but I do occasionally do some sprints on the highway but not every days. Obviously had owned other cars in the past and never had rotors fail this quickly.

Any thoughts are greatly appreciated!

 

moved to W213 AMG forum...

 

This is an insane problem to have. I have to say I can't help, maybe something with your calipers??

 

So first of all, warped rotors is mostly a myth. It would take an extreme force to actually warp an iron rotor, at least the size of a performance rotor in an AMG. I know, shops and techs do like to use it as a lazy diagnosis to avoid having to actually measure the runoff on the rotors itself and after mounting the rotors, and not just the hub. What's most often diagnosed as warped rotors are actually uneven pad deposits on the rotors from overheating the pads or an issue with the caliper or both. If you have a stuck caliper it will overheat the pads, which in turn starts splotching pad material over the rotor and then you have vibrations. This is frankly insane to just keep replacing rotors and pads and hope for a different outcome. There's obviously a bigger problem here.

The other thing since you mention you do occasional sprints, does that involve aggressive braking as well. Uncontrolled heat up of the brakes can also result in uneven pad deposits. Before you go for any spirited drive with a fresh set of rotors and pads, or on your first spirited drive you should gradually heat up the brakes to build up a layer of pad material on the rotors. This is known as bedding or burnishing the brakes. It will ensure optimal performance and an even layer of pad material on the rotors. You may have to repeat it periodically, because normal daily driving with mostly cold brakes will scrub the layer of pad material back off the rotors. This is known as the abrasive mode. Below is a pretty good video that explains the process and the benefits.

 

So the tech from the shop actually measured the run out on the hubs and rotors. “With the calipers removed, checked run out on both front rotors.
Found both rotors produce a run out well over the acceptable
limits, roughly 6- 7 thousandths of run out on both rotors. This is
consistent with the shaking felt on braking. Removed both
rotors, noticed some movement in the rotor hat when releasing
the anchor screw. Measured run out on both hubs, roughly one
thousandth measured which is well within acceptable limits. ”

I definitely brake hard to get speeds down but just to clarify I didn’t do any sort of aggressive driving well after 500 miles on the new rotors. Also at most it’s a 1-2x sprint. Also driving done after putting some heat on them. I never push it until the transmission temp has reached its optimal temp.

 

Bad calipers or bad wheel bearings.
Have them checked.

 

I had a similar issue with my GLA45 few years back
first set of rotors replaced at around 7 K
then every 2 k miles , same thing
diagnosis : warped front rotor,
fix: replace front rotors
all repairs were under warranty as problem started before 10 k which seem was the cutoff for brake coverage
I got sick of this and sold car

 

They also checked out the caliper and no signs of fault. Just including tech’s notes “Continued with inspection of the brakes and brake system
looking for signs of obvious damage or mechanical failure.
Removed both front calipers and checked caliper piston travel
and retraction, no pistons appear to be sticking or binding and
the pads move smoothly in their anchors. Also found no
abnormal resistance which could indicate a collapsed brake
hose.
Performed a short test on the vehicle to check for faults set or
stored that could be related to the conditions reported, no faults
present that would relate to the shaking.”

 

Silly question but are the wheel lugs torqued properly? In the past I found that if the wheel lugs were too tight, the rotors would warp.

 

If everything mechanical checks out then I'm pretty much stumped. The only other things I can think of as well are improperly torqued wheel lugs or a streak of bad luck with faulty rotors from the factory or damaged during transport or poor installation. What's the commonality between all the failed rotors? Were they all installed by the same place? The only other thing left is your driving style.

Personally I've used aftermarket rotors on my current C63S coupe, and previous car. Both times I went with full floating rotors. They have springs to let them move laterally and self-center between the pads. Makes for optimal pad contact and allows for thermal expansion not just vertically, but also laterally. The OE rotors are only semi floating. I didn't have issues with them, but the aftermarket rotors are cheaper and better.

 

This was mentioned by the most recent shop including over application of lubricant. There was some flex in one of the rotors when the third shop tried to remove it from the hub. They did mention that it could contribute to the problem but to happen 4x in a row is highly unlikely.

This was how they summed up in their notes

“Researched issue in an attempt to find any documentation
related to customer's concern, found reports of similar issues
but no definitive solution. Multiple reports indicated that a lack of
hard braking could potentially lead to build up in the vents and
grooves on the rotors, did notice some material in the recesses
of the rotors. After several hard stops however on subsequent
test drives, little to no improvement noticed.
Recommend at this time replacing the pads and rotors with
factory equipment, wheel hubs should be cleaned and
lubrication kept to a minimum. All brake hardware should be
replaced along with the rotor anchor screws, the screws will
need to be torqued to spec. The break in procedure for the
replacement pads will have to be adhered to exactly to ensure
proper bedding in of the pads and heat cycling of the rotors.”

 

See mention of the torquing to spec in the post below but basically the shop said for it to have it 4x in a row is highly unlikely. The first three jobs were done at MB dealership. The fourth job was done at a third party independent shop. The rear pads and rotors were done when the third set rotors and pads were placed and those are doing fine. So far I’ve done all my work at the MB dealership and haven’t had any issues. I had a GLS 580 prior to it and all my work was done at the same MB dealership. I haven’t had any issues with their workmanship.

Because of this issue I’ve taken my car to two other independent shops. The most recent didn’t install but I was hoping to see if they could figure out the problem. They were also stumped and couldn’t figure out the cause. Clearly the rotors are warped. There is definitely some component of heat being over generated or improper dissipation of heat.

In terms of my driving style I drive fairly well. To keep that somewhat objective my previous car was a 2013 Audi A6. I bought it new and drove it for 188k miles before selling to get this car. During that time period I’ve gone through three brake jobs. I am driving this car not much different than my previous car but definitely have hit numbers that I wouldn’t on my Audi.

 

I heard of a similar case . A good friend of mine had a (non mercedes vehicle) . Went through numerous sets of front rotors ,front calipers & brake hoses to no avail. Ended up finding the master cylinder rod was out of adjustment, just enough to create a light brake drag situation. But not enough to be discovered . Didnt have any burning smells or anything - but over time it was enough to continue warping rotors.

Now i'm sure not all master cylinders have adjustable rods - which would void this scenario. Figured I would throw it out there anyway.