eki912

I am puzzled....

Have seen this before on many (if not on all) cars I have owned, brakes stuck a bit after being garaged for several weeks. Drove out yesterday, started moving, with the familiar BANG when pads released.
Nothing new there, then drove as usual, and as always before, the brakes were noisy and juddered and you felt it in your pedal too.
But, previously on all my other cars the noise and judder has gone away after couple of hard brakings from speed. But not now !!!

Drove several hundred miles yesterday, with some heavy brakings and plenty of normal brakings, the judder is still there !

Is it the pads/discs gone bad ? And if, why ? Or should I just keep on driving and braking more to get all rust and crap out of discs and pads ?
It can only be felt when braking hard, no problems on slower speeds with gentle braking.

Naturally, have read hear about the brake issues GLKs can have, and now a bit worried about that too. If it stays like that, is this issue covered under warranty?
Fearing of discs damaged....

Another question, we have the rear camera, nice. But sometimes feel like the parking sensor/buzzer would be more useful. Possible to have both ?

Diabolis

It sounds like you have warped your rotors. It usually happens when you park the car with hot brakes, and the area underneath the calipers / brake pads doesn't get to cool off at the same time and rate as the rest of the drake disc resulting in warping.


If the car is under warranty and they are warped, they will replace them for free despite the fact that it's a wear-and-tear item.

equetefue

How many times will they replaced them? All the way through the end of the warranty time/miles, or just the first 12k/1yr?

Diabolis

I don't know whether warped rotors falls under the "wear and tear" period or the vehicle warranty, seeing as the specific defect (warping) is not exactly a result of normal wear and tear.


In terms of how many times they would have to replace them, the answer is "as often as they fail for as long as they are under warranty". If they keep warping every two months and the warranty on the repair itself is 90 days regardless of how long the car warranty may be, you'll be getting new rotors free of charge for the next 20 years.

eki912

oh man.... Do I need to go and fight to get them replaced under warranty ?
Or is the fault so common, that they will do it without any questions asked ?

Weird though, if it is related to being parked with hot brakes ? As we washed our GLK properly, by hand, for the first time ourselves. Dried it, and drove back, about 5 miles to garage. And definitely didn't drive hard or brake hard. More the opposite ! As I always (nowadays) drive easy and gently. So how can the brakes become hot !?

Could it be something else in that car washing process, that caused this ? Soap/foam/water in pads or rotors? Residue of cleaning agents left behind ? Allthough one would expect the brakes to dry in that time (30-45 mins spent drying and vacuuming), with the added 5 miles drive to garage?

Diabolis

Were the brakes hot when you washed it (as in did steam come out when you sprayed water on the rotors)? That would most definitely do it - I myself have destroyed a set of rotors on one of my other cars doing exacly this. Otherwise no - the rotors will not warp just because they get wet. Some of us drive through deep water puddles, slush and snow for five months of the year so water on its own wouldn't affect them. It's only if you cool (or heat) only a portion of the rotor and the metal doesn't contract (or expand) uniformly that usually results in warping.

NYCGLK

How would that really happen? Threshold braking into your driveway?

NYCGLK

Have you inspected your rotors? Take the wheels off and have a look. You might find your answer. Or go to dealer/indy and have them look. Btw, inspecting brakes is part of B service, if you service your car at dealer.

Yes, you can have parking sensors, but they are fugly especially the aftermarket ones. Just get used to the car. I back into every parking spot and have no need for sensors.

Diabolis

Sorry - I keep forgetting that this is the GLK, not the C63 forum.

Then again, seeing as the GLK is not exactly a lightweight and the brakes are somewhat undersized for the vehicle, it's not inconceivable that they were hot enough from "normal" use that when he sprayed cold water on them they warped. I am assuming that it's not just uneven pad material transfer / deposit on the surface of the rotors as that would get scraped away during a couple of panic stops which IIRC the OP performed. If it's not that, the only thing left is run-out due to hot spotting at high temperatures or rapid uneven cooling.

eki912

Have been too busy doing other stuff, and not used the GLK for a while...
took it out for a drive last weekend, and nothing new, noisy brakes and judder.
Booked it in, tomorrow morning.
Lets see what they say, didn't promise they will be replaced under warranty...
But naturally didn't say no either, yet. They will check and investigate first.

What I read from here, I should be covered by warranty, am I not ?
Car is only a bit more than one year old, and about 15 000 miles or less driven.

What are the steps to take, if they still insist it is a wear and tear thing and try to charge me for it?
99 % sure it is again the not that uncommon warped rotors issue. And when I say again, I do not mean it has happened to me yet. Just what I have read from here happening to others too.

Diabolis

It should be a warranty replacement. See https://mbworld.org/forums/glk-class...er-50-mph.html.

eki912

Car was in Manhattan MB for a day, they changed the warped front rotors and installed brand new pads while at it.
All done under warranty, like it should.

Me happy again ! They even washed our dusty vehicle !

Also very impressed how they handled me, my car , and all people waiting there. They really make the effort to make You, as a paying customer, to feel good with that visit there. Very efficient.

But, then again, this makes me wonder.... how should I then wash my wheels/car, if no water can be used on them ? As I can simply say, I don't drive hard, or brake hard to heat the brakes too much. Just a normal (middle aged) driver, on a diesel GLK, drove about 3-4 miles to a car wash, waited in line for 5 mins for the washing place to come available (thus cooling the brakes anyway, if they even managed to get warm during my drive there) , washed the car and wheels with high pressure water with foam and all that. Rinsed it properly with water, including the said wheels, never tried directly to wash the rotors but water naturally goes in them. After the wash, drove aside, dried and vacuumed the car (for about 30mins) and drove back in to my garage. And didn't notice anything unusual. And I am fully aware of those rotors & pads being wet, so I did use the brakes to dry them ( to avoid the pads rusting stuck to rotors ) when I drove back.
My point is, what did I do wrong here ? If the car wash really did cause this ? What do I have to do differently next time ? Drive more after the wash ? Tow the car to a wash ( joking ! ) ? Not wash it at all with water .... or is it also age related, meaning the rotors are more prone to warping when you have covered enough miles ? Or was it just another pair of bad rotors ?

Diabolis

Glad it all worked out as it should at the dealership.

Of course you can wash your wheels and brakes. The only thing I was insinuating is that very hot rotors that are rapidly or unevenly cooled can somethimes lead to warping, but that certainly doesn't appear to be the case here. The GLK weighs 4500 lbs empty, and the rotors are IMHO somewhat undersized for the weight of the vehicle and/or possibly made of softer steel in order to minimize the possiblity of brake squeal, so it's quite possible that it's just par for the course.

Now, I don't want to split hairs here, but you did write "And I am fully aware of those rotors & pads being wet, so I did use the brakes to dry them ( to avoid the pads rusting stuck to rotors ) when I drove back." If you had a 3 mile drive from the car wash to your house, your rotors would have dried in the first minute of normal driving or by the time you stopped at the first traffic light. Maybe you overheated them trying to brake harder than necessary on the way back and left them hot in the garage AFTER the wash? A spirited drive back home without giving them enough time to uniformly cool off before you park the car is the only possibilty I can think of - again, assuming that somehow it was something that you did for the sake of argument as opposed to a design "flaw" in their construction.

It's not the water per se or any surface rusting / binding - some of us drive our MBs (GLKs included) in snow for five months of the year where there is snow build-up in the wheel well when we park our cars every day, and they rust and bind every single day - all without any warping issues. Short of or having them crushed by a hydraulic press, overheating and uneven cooling is the only cause that can make them warp.

eki912

Yes, I did use then on several slow speed stoppings. As I live in Manhattan, no possibility to speed up or brake hard (like on a highway).
Didn't use them over excessively, or kept my foot on brake for a long time either. Just normal driving, but I did use the brakes, to dry them. More than I normally would as I often drive gently, and use the engine for braking a lot. If possible.
But still sounds like the only logical explanation, mainly because I didn't do anything else "abnormal" , than washed the car.
How can they get THAT hot, in my driving, I can't figure out ?

But anyway, test drove the car to JFK and back, all back to normal, car is silent, me and wife happy !

Diabolis

It's not your driving per se - it's the kinetic energy (which BTW is proportional to the square of the speed) of 4500+ lbs moving at whatever speed being converted into heat, which is being absorbed by brake rotors of somewhat inadequate size and heat dissipation characteristics for the application. You are not to blame for this. Trust me - I am the first person to call a spade a spade and jump down someone's throat, but in this case you did nothing wrong. One of the fronts just wore down to the thickness where the heat from normal driving was enough to warp it. That's all.

NYCGLK

I just put GLK front rotor next to '96 Porsche 911 turbo rotor, since I have both laying around...guess which one is bigger...GLK rotor by a few mm. The pads don't look small either.

But yea a lot more weight on the front in GLK than in a rear engined car under heavy braking.

NYCGLK

or the pad material transferred to the rotor after being hot and sitting in the garage for too long.

Here is an interesting write-up on this issue.

eki912

Another point to think about....
if I managed to warp my rotors by my gentle driving, 2 adults in my car, no luggage, what happens to those who pack their GLK with 5 adults and some luggage ? The weight goes up a bit, doesn't it ?
How about those guys who tow a trailer or similar?
I sort of do understand the hotspot theory, so the area behind the pads cools unevenly compared to the rest of the rotors. But how can I avoid to do that again ? As most people drive their car, brake their car and just park their car. Without worrying about the rotors too much. Even after wash.

Diabolis

Your "flat six" 993TT has 322 mm cross-drilled and vented rotors all around and weighs 3300 lbs. The GLK is 4500 lbs and has 330 mm front / 300 mm rear rotors that are only vented, and as you pointed out, the weight distribution is also a tad different. Plus, I suspect the MB rotors are somewhat softer too.

Diabolis

Look... it's not that you managed to warp them - I think in this case it would be more correct to say that the rotors warped without excessive help from you, unless you came in "hot" (as in you were evading the authorities ) and turned off the car.

The problem with warped rotors on the GLK is common enough to suggest that there are some design shortcomings in the sizing and/or material used. Not so common that it happens in, say, 30% of all cars and/or requires a recall, but common enough to suggest that perhaps MB could have used 350 mm fronts for example like they do on the ML500 or perhaps thicker ones.

As for towing trailers, most of them that can carry any significant weight have their own (usually electric) brakes so it's normally not an issue, and furthermore, when I tow a trailer I usually start braking three times earlier than I would without one and I only travel at half the speed.

eki912

After being happy for a while, and gone for a loooong vacation ( not using the GLK ) drove the car first time last weekend and.....brakes are noisy and vibrate again !!!
I am now suspicious of some rust buildup on rotors as I have driven less than 1000 after the replacement of my rotors & pads.
I tried them several times, hoping to clear possible dirt/rust from rotors. No help. Couldn't do any proper hard brakings though, had friends in car....
This can't be happening again...

eki912

And the GLK was taken to MB Manhattan this morning for them to have a look what is wrong now.
The same symptoms, a bit less bad this time though, but sadly again when I brake from highway speed with any force from my foot the whole car vibrates badly.
Definitely brake related. Hoping it to be a rust spot on the rotors but it has not disappeared even after several hundred miles of driving.
Letīs see what the conclusion is this time. They replaced my front ones less than 500 miles ago...

Diabolis

That is either really bad luck, or something specific to your car. Are you by any chance using aftermarket brake pads? Perhaps you have a "sticky" front caliper that's overheating one of the fronts? Did you bed in the last set of new rotors properly?

eki912

Received a call, rear ones gone now ! Pads and rotors ! And this car has less than 16 000 on it..... and to make things worse, they are NOT covered by warranty !!!!!

Are the brakes really this bad on this car !?!?!?
Less than 16 000 miles , and all brakes are now replaced, not only pads but also all rotors!

The good thing is, now they are all renewed and we should be happy, but really, am I supposed to replace all 4 rotors and pads every 20k ????
The first owner was a lady, and I know she drove gently, and so do I, so it simply can't be that we have driven her too hard. No way, more the opposite.

Naturally I tried to get them to understand the low mileage and all that, still NO. I have to pay for it.
Anyway, I wan't the car back, so I told them to get it fixed.

Should I start to fight with MB USA to get refunded for the cost of this ( due to low miles ) ? Or just pay it and drive it ?

Diabolis

I thought you said the rotors had less than 1000 miles on them, but you're now saying that they had 16K miles. That's a rather big difference - what are we missing here?

And, I have yet to hear of a REAR rotor causing vibration through the stering wheel - you'll feel it in the pedal and your butt, but it doesn't make the steering judder...