Falco

Yesterday i left work a little early and went for a canyon rip...Did my favorite SMM loop of stunt, shueren and piuma. AMG_55 knows this route as its the one we ran last fall and at the end, many people had smoking brakes!!!

For those not familiar with it, it is very twisty road with pretty good elevation changes. So i did the run with no stops. Car was flawless for 90% of the run and then the brakes gave out...super squishy with no braking power...so i slowed and they came back after about 5 minutes of cooling.

So, is there any easy low cost way to mitigate brake fade(other than limiting brake use!!!).

joec1101

Try using the transmission to downshift and slow you down - if you have the 7-speed auto (not sure, but maybe the 5-speed auto does this as well), you can depress and hold the shifter toward the left and it will yield a performance up and down shift. You can also just downshift manually whether auto or manual to slow you down and maintain your speed when going downhill.

dsb

I wouldn't do the suggestion above.

The first time I took my car to the track, there was two issues. The power steering and transmission. Both of them seem to cook. I think Easty posted similiar issues. Suprisingly, I experienced no brake fade. Even if I did, I think I would first use a different type of brake fluid. If problems persist, you can use other brake pads.

I wouldn't put undue stress on the engine. It's not a semi-truck... no need to engine brake. The transmission is not made for that IMO.

transferred

That surprises me. I'd expect brake fade on the track or drag strip but on the road- maybe you were cornering too slow!
Do you have the uprated AMG brake pack that is optional on the 55 or are they the standard- and still pretty hefty- std discs?
I know non-performance pack M3 brakes can fade too, but my model has been perfect so far. I'll have to seek you out when you're just finishing a run and claim a W back for the M-boys!

SLK55R

switch to the 14.3 rotors of the 030 package.

dsb

Explain something to me regarding the 030 package.

First, it is my understanding that the rotors are larger but the calipers are the same as the std package, right?
If this is correct, then I expect they use the same brake pads, right?
Now, if this is correct too, then the contact patch would be equal to the std brakes.

All that being said... if I'm correct on those things, then how would the larger rotor provide a benefit? Does is dissipate heat faster?

SLK55R

Twofold ...

Increased performance (brake torque) by virtue of the increased leverage of the larger diameter rotor.

This increase in diameter increases leverage, braking power and efficiency (in the way a fulcrum and longer lever reduces the effort of lifting an object).

Read that online ... so maybe thats why?

dsb

Sorry,

Maybe I'm stuck on stupid.

I could understand if the brake pad was larger too, but I think it's the same.
I guess I'll do some searches online. I still don't understand UNLESS it does use larger calipers and/or brake pads.

CynCarvin32

I know that loop all to well. Dont drive it as often any more but I have destroyed man a MB's braking system there. Push hard enough down stunt and the brakes wont some.... they turn to flames.

Best way to fix your issue would be a better set of pads. You are just going past the operating range for the factory pads (temp wise) and then they turn to mush. With a better pad the fade will set in at a higher point.

If you want to really solve it but a front stop tech kit and sell the AMG brakes to a C or SLK owner. A StopTech kit with Padgid Blacks will never fade.

In canyoning I find that braking a tad earlier and just not ripping the straights saves the brakes and stops that destruction. You can hit 105+ on the long straight going down Stunt but why? So you can melt your brake pads? Just take it easy since its about cornering not showing the honking motor!

I always run Piuma up since I think its more fun that way. Down it is just to hard on brakes and they always go away on a stock car. The 5 hair-pin turns comig down are just to much for stock brake kits.

Canyons are harder on brakes than racing due to the fact that you are on the brakes every few seconds. At the track your brakes get a long time to cool between real applications but in the canyons you are always laying on them. I know your pain!

Pads, Rotors, and Tires every 8k miles.... the way of the canyons. But I jsut dont do that driving any more. No time and its getting to hazardous. WillowSprings September 10th! Thats the place to be =)

bloflin

Not an expert on brakes, but my thoughts:

Larger rotor (even w/o largers pads) could mean rotor does NOT heat as much or as fast

Larger diameter rotor and since the pads sit at the outside edge of the rotor, means more rotor surface per revolution go past the pads (even though pads are the same size).

Think 8" and 12" pizzas but using your same size mouth. More pizza if you eat around the 12" pizza one time.

vraa

Don't use your transmission to slow down your car. You have an engine to go, you have brakes to stop.

Have you thought about looking into the evosport rotors. If I remember right, dinko tried to get a group buy on them. They are lighter and a direct replacement for the E55, I'm not sure about hte SLK55. They are also designed with cooling in mind. Might want to take a look into it?

www.evosport.com

dsb

Makes perfect sense. Thanks.

BTW, the pizza metaphor was funny. I got the point without it, but it was funny.

Falco

Thanks for all the replies. Looks like the first step is new pads...then rotors then full stoptech kit if it doesnt stop! CynCrvin32...since you now the loop well, you know what the brakes go through on the downhill of piuma! and yes, i am with you on the canyons, I never get over 60 of 70 even on teh straights as the fun is in the cornering!

Easty

Not sure why your having this problem I've done many track events and the brakes have never been the week point. And it's not speed as mentioned above. I've raced a few times at TWS in college station and it's a 145mph straight into a 60mph turn and most of the track is high speed high braking. The car is a little tail happy and especially under braking use this as an advantage to get it to autorotate and you'll find you need the brakes much less. try to keep it smooth, try to learn left foot braking, it feels weird at first but its so good to be able to keep the car balanced. if you stomping on and off the brakes it's not good. Smooth on the brakes and gentle smooth off. I see how some people drive and it's no wonder they burn through brakes. with the large tyres point this car any where but straight and it slows very fast on its own without touching the brakes. As said above go into corners a little you'll probably find you come out a lot faster without running your car into the ground. If your tyres are smoking it may be fun but it's cetainly not the fastest way around.

Falco

Track driving is different than canyon...i have 1 lane and cannot setup perfectly, so you must brake sufficeintly and corner exaclty. Also, i dont know of a racetrack in the world that has the elevation changes or the curves of the loop i posted. Check it out here:


http://maps.google.com/maps?f=q&hl=e...85831&t=h&om=1


Total loop is about 10 miles, with 1/2 of that ascending 1500 feet and the other ahlf descending 1500 feet. So, you can see that spirited driving under these conditions will easily fade or smoke many brakes!

Easty

http://video.google.com/videoplay?do...east%40uk2.net This is cresson just south of fort worth the track is 3.1 miles and a lot of elevation change. the avg session which you do 8 off is about 6 laps. I've driven and riden bikes a lot and the track wears everything down a lot faster. You just cannot driver like that on roads.

Falco

alot of elevation is not equivalent to mountain roads....also the track is more than 1 car lane wide...

Please quite trying to say it has to do with the driving etc etc...the stock brakes simply arent up to a 10 mile non stop thrashing of hairpin turns with 60-70mph approach speeds, with half of it downhill.

Alba

For a solution short of a full brake system upgrade, you could put a set of Porterfield R4S pads on the front and see if that makes a difference. Pads should set you back < $200, labor is up to you (I did mine myself, but I have done brakes on Mercedes several times). You can STF for instructions if you want to try a DIY solution.