Drilled, slotted or plain


Mercedes CLS550
Hi, my first post, hope you like it.
I have a 2014 CLS 550, 30000 miles with minor brake tremors, it has Drilled Front Discs. I have not been able to track down the cause, Discs look good, no wear or distortion, wheels and new Michelins balanced. I have read that Drilled Discs are weaker than either slotted or plain Discs. I would appreciate everyone's input, please
Hi and welcome:) |B
Your "minor brake tremors" will almost certainly be warped rotors/discs that can be machined out. I have experienced exactly that quite a few times over many years and call my on site mobile brake machinist who uses his on car machine to mill them back to true PROVIDED that they will still be thicker than the minimum specified thickness.

When it comes to the type of disc there are many cases of drilled discs with cracks radiating from the drilled holes so FWIW I would recommend plain or slotted depending on weather it is a road only or tracked.

Thanks for your response, I will check that out an maybe replace the Discs for non drilled
Drilled is overkill for the roads anyway. They keep the pads nice and clear though. I'd stick with grooved or dimpled for the best of both worlds.

Putting a bigger disc and caliper on will have a better effect than adding slotted or drilled disc.
Let us know what you decide and what you go for and how you get on with them.
I've put drilled brembos on the fronts on the c220, with brembo pads. As much for the look as anything else. They do stop well, butno better than standard, and slightly noiser on hard braking. But they look good so what can you do:lol::rofl:

No issues with vibration. Done about 5 or 6k with them.
Thinking of going with plain and ceramic pads, ordered the pads still not sure slotted or plain but seems that the consensus is that drilled areore susceptible to cracks, breaks and warping,.
CAUTION if you track your car then try to do a cool down lap with no braking and when parked DO NOT apply the hand brake as that can/will lead to a warped disc also move the car slightly after a little while to move the hot spot away from the same place on the disc.

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