I've got two different quotes to what's wrong with the car. One quote said the castor bushes need replacing and the other said the rotors, the MB dealer said the castor bushes and a normal mechanical workshop sais the rotors. Now I am confused cause I've seen in the forums the rotors cant be skimmed which I can clearly see they were but I know worn bushes also cause shuddering so maybe its a combination? It only happens at speed of over 90km/h or so.

Typically if the rotors are slightly out of round, you will get shuddering only when on the brakes.

It would be hard to warp the rotors on a C32/55. It might just be brake pad build up on the rotors. Have you tried making 3-5 hard stops from 50-60mph (where safe) and see if that cleans the rotors?

Depending on how bad the deposits are, the only option is to turn the rotors. I had the problem with OEM pads doing that on track days.

Thanks Ill try that Zep and Kent what do you mean by turning the rotars? Machine them?

You can turn (re-grind or re-surface) traditional rotors no problem, even drilled , but usually only once. Yes, MB doesn't recommend a grind, only new like many other manufacturers.

Think about solid vented rotors, or slotted vented; they last longer and have more material to soak up the heat which in turn will prevent warpage . It may not look as cool tho as the OE drilled rotors....

Def try the two feet on the brake pedal from 50-0 first a few times. Perhaps you do just have some pad material built up.

Your assertion that slotted or non drilled rotors is better at stopping deposits is not true. Drilled rotors tend to crack under extreme braking but they get the excess heat out.

Please see the articles on Stoptech's website

http://www.stoptech.com/technical-su...nd-other-myths

Where did I say or even allude to that slotted or solid rotors are better at stopping brake pad deposition?

Very true that drilled rotors often develop cracks. Heat and gas can escape easier with drilled (the whole idea) but also the rotors will heat up faster and warp faster with drilled under heavy usage due to less material (metal) to soak the heat. Simple physics.