sly55

sorry if this is a repost, but when this comes on, as long as you monitor for brake fade, is it ok to keep pushing it for a bit!?!? The worst thats gonna happen is that your not gonna stop as quick right? nothings gonna disintegrate or anything!?

benzmodz

You get the "BRAKES OVERHEATING" light and then it doesnt stop.

I know of one example where an SL65 owner was invited to an AMG day in Sydney and he was the last person into the AMG on that day. The previous drivers had used far too much torque + braking and managed to super-heat the brakes.

The car was at full sprint going over the finish line and coming to the corner ... no brakes. So it was a matter of spining the car and losing as much speed as possible in the dirt.

If you dont have that kind of clearance then I would think it was a good idea to follow the message ! The error code is stored in the car, so if you have an incident it can be read back via an OBD reader and then you have a bucket of whoop-*** from the insurance company and then trying to explain what happened.

Dogshine

I also hear you can end up with some gold calipers... .. from the heat cooking the clearcoat on the paint on the calipers. The look really GOLD too....

I saw pics of some on the cls55 forum from a car that used to be on the amg challenge circuit. do a search....

pas

This is the opposite of my experience. I did a driving school at NHIS with my E55 and my brake overheat warning came on during my third and fourth sessions on the track. I did not notice any degradation of braking performance. The sessions were 20 min each and they were about 1 hr apart. After the warning came on though I didn't go down the front straight at full speed so I wouldn't have to brake so hard at turn 1 but on the rest of the course I drove hard and had no problems with the brakes.

I asked this question before but on one had an answer, does anyone know exactly what temp is being measured?

I assume it is brake fluid temp but at what location? The other thing is I am willing to bet that many cars on the track that day had fluid temps similar to mine but the MB is the only one that provides a warning.

sly55

interesting... well prior to my light coming on, the brakes felt 100%, no sign of fade or anything, thats why i was wondering how much lee-way you actually get after that light comes on to the actual onset of brake failure. Being Mercedes Benz my own thoughts would be that once that light comes on you'd still have at least a bit of a reserve of braking left. Although that said, most of our cars are prefacelift E's that were the ****test load of mercs to come out in a while, and flunked out on their satisfaction points survey thing, lol... jokes...

tommaey

You have brake by wire brakes. They are designed to mask brake fade. Through the pedal, you aren't going to feel any degradation in brake performance until a certain point, and then suddenly the car just wont slow down.

I think it's a good idea that mercedes has made the brake overheating warning come on sooner than later - because you guys are still pushing it when the light comes on. What if it was designed to come on even later - would you still be pushing the car hard around the track?
yep!

CynCarvin32

Let me clear some items up about this break over-temp warning. It is first of all NOT something that stores an error code so your insurance company wont be beating your door down about this -- like those people know about the computers in an MB anyhow.

Second of all there is no temp sensor in the vehicle at all regarding the brake temps. The car has an algorithm that it uses to determine when the car COULD be getting near the point of brake fade. It is not a simple number of brake applications but instead it measures the force of the application, the speed at which you are traveling, the delta value in speeds etc and then when the car thinks you have asked too much of the brakes, the light comes on and says hey watch out bone head! I have seen an E320's breaks burst into flames before the brake overtemp light came on so clearly there is no sensor reading pad, rotor or fluid temps. This info came from the head instruction for MB tech training.

Finally you will never feel brake fade on these cars until the pad has gone right past its operating range and is indeed cooked and done -- no more stopping friction. The SBC system compensates for fade by applying more brake force as the system registers a less effective brake pad. As the car sees brake applications not slowing the vehicle accordingly, it increases the force of the applications to compensate. This makes the system work harder and it feels as if the brakes are indeed free from fade. In reality the SBC system is simply giving you a false feeling of security and will eventually reach a point of total failure if you don’t allow the brakes to cool down. This feature seems like a hazard not a safety feature but I think MB figures most owners will never keep pressing hard once the algorithm triggers the light saying hew brakes are getting to hot mr. driver man.

Does this clear anything up??

sly55

thats great info there thanks. very interesting! i would have simply assumed there was a temp sensor somewhere.... as it was only when i had to come to a dead stop at a traffic light, a few seconds after stopping, then the light flashed up. i assumed coz id been hard at it for ages, then stopped and hence cut off the cooling effect of the vented disc, the temps just rose while i was sitting there until it triggered the warning.
Then it took about 15minutes!! of slow driving avoiding the brakes before the light went off!! I was hammering through the hills for over an hour tho, so i guess thats not too bad.

stevebez

If you are stationary after a hard burn on the brakes do not keep the brake pedal depressed to keep the car from moving. Use the handbrake or put it in park. Keeping pedal pressure on a hot disc will quickly cook the caliper and the brake fluid and thats when things get dangerous - hot brake fuild will boil and the system will get spongy... and brakes will fade. Keeping pedal pressure on a steaming rotor will also make it cool unevenly adding to potential warping...

To get to the temps where the mechanical friction of modern (some are ceramic) pads fade on their own requires some very serious hard driving (i.e. to the point where the glue used in the pad melts and mush ...) In my experience its the brake fluid that gets too hot way before the pads oveheat - especially on systems with racing or performance pads.

When I went on an AMG Performance day earlier this year we did 4 x 1 mile runs to max speed and braking down to 30mph back to back ... after the 5th run the brake warning light came on and did not go off for mbe 10mins even after driving through water... so it seems the system is not temp sensor related but perhaps when the SBC needs to add more pressure to get the desired retardation then warning is triggered. Furthermore the instructor was not fazed in the least by the warning.

P.S. Does anyone know to which brake system the SBCH feature applies the brakes? If its the main brake system this should not be used either after long hard braking for the same reasons noted above.

pas

Well now we know thank you for finally clearing that up. I am really suprised the car has no sensor but I guess it makes sense considering how technology driven this car is.

When it happened to me I was at NHIS so I drove out of the track and down the road without touching the brakes until the warning went away, then I drove back to the track and parked it. The brakes were still hot as hell but the warning was off. Thanks for the info.

CynCarvin32

I was shocked that there was no sensor and I to have had the light come on after the car is stopped in the middle of a canyon drive (no airflow over brakes). But look at the brakes and you will see there is no temp sensor in the pad, caliper or rotor. So there cant really be anything there.

But shame on us all for stopping with warm brakes!!! The number 1 way to put serious bad deposits on the rotor and create a very shaky car under braking! =)