pawnman5

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Dan,

('05 (R171) SLK 350) I have some small waves in my front rotors. The brakes do not surge or pulsesate. But if I have to get on the brakes hard I can hear a noise coming from them. My mechanic thinks the pads are to hard and are wearing the rotors. I'm having him turn the rotors just to true them up. I purchased the car used with 16,000 miles so I have no idea what pads are on the car. What do you recommend for pads? MB stock pads? Thanks for your help.

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DansSlk

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Its hard to tell exactly what the system feels like on the SLK because the brake system is basically electric only if the computers fail is your foot actually having any direct effect on the pistons 99.9% of the time its computer controlled you moving your foot is simply asking it to brake this can lead to a numb feeling and small vibrations are not fed back to the pedal because its isolated.

I have never had any probs with the MB stock ones they seem to be just right for road use so i would highly recommend them if they are not currently fitted if they are then maybe look into the calipers pistons.

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pawnman5

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Thanks I'll go with the MB stock pads.

Cruzer 8

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I didn't know that turning the rotors was acceptable -- at least the drilled ones ---- is this right or wrong ?

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cyberdrakon

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Dan, i'd like a little more clarification here...i thought the SLK has a traditional hydraulic brake system? isn't the electrical component more of an emergency booster? Or is it more like the E class and S class brake by wire system?

pawnman5

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Cruzer, My mechanic is checking with MB but he doesn't think it would be any problem to turn the rotors. He has turned drilled and sloted rotors before, as long as they are still within the specs.

DansSlk

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OK mate,

The E, S, SL, SLR and for a while CLS class cars use SBC (Sensotronic Brake Control) so there is no mechanical connection between the pedal and the brakes this was a crap system and MB are in the process of phasing it out it was overly complex due to all the backups and things constantly went wrong in fact another recall is doing the rounds right now.

The SLK uses basically a normal master cylinder with vacuum assist and a sensor and solenoid to measure pedal travel and operate the diaphram when you press on the pedal you do move fluid like in an ordinary system and if the computer fails then the system will just feel very sloppy but you will still have hydraulic brake control when its working normally the ESP pump that sits between the pedal and the brakes uses its internal reservoir to control exactly how much pressure is applied to each individual brake.

So basically in normal operation the system is electronic the sensor on the master cylinder detects how far and fast you have moved the pedal and informs the ESP of the calculation it then operates the system itself as i explained above, the resistance you feel is provided by the ESP pump.

Sorry if it sounds a little fussy i will try and have a think of how to explain it better or will get the WIS sheet posted up or something but basically imagine 2 systems a low pressure and a high pressure with the one constantly keeping the other topped up hence the need for the servo to activate the diaphram in BAS mode to keep the pressure correct.

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pawnman5

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Thanks Dan for the information. Also do you know if the rotors on the slk 350 can be turned as long as its within specs?

Pawnman5

DansSlk

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As far as i know so long as they are within spec its OK, but not if you have cross drilled ones fitted

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pawnman5

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Thanks, we'll see what MB has to say.

pawnman5

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Dan,

MB here in Oklahoma / USA is unable to tell me if the rotors can be turned. Can you tell me what the min. is on the thickness for the front rotors (to keep within spec.) My brakeman says he has turned lots of drilled and sloted rotors without any problem.
Thanks,
Pawnman5

DansSlk

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I can have a look for ya mate no probs

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