I have read several strings about cross drilling rotors. I have done this in the past with near disastrous results . Here is a post from another Benz site. Read and learn so you don't have to learn from experience.

Date: Thu, 22 Feb 2001 17:24:18 -0500 (EST)
From: "Richard J. Sexton (Mechanic Role Account)" <richard@mbz.org>
Subject: Re: [BANNED] One more little thing

Have you tried the ATE power discs Roger?

At 04:53 PM 2/22/01 EST, you wrote:
>Alvaro suggests:
>
><< Cross drilled rotors do 2 things.
>
>1 reduce un-sprung weight.
>2 allow gasses to escape from the brake pad under extreme conditions.

>There is one more thing that cross drilled rotors do (brake discs, more
>accurately) and that is CRACK. They all do and cracks lead to breakage.
>Further, no manufacturer uses drilled discs. Those holes are cast in the
>disc. Drilling leads to stress risers which leads to an appearance much like
>a pizza with a piece or two missing.
>
>Don't even think of drilling your discs. And no, countersinking the hole will
>not help.
>
>Roger Ellingson/Seattle
>

Well don't look at any W220 chassis(2000 & later S-class) as they come standard with cross drilled(Brembo) rotors, they might come apart. I used crossed-drilled rotors for years w/out any problem on auto-cross/street Benz's.

The gases spent by extreme braking are real and the most effective and safest way to deal with them is with slotted rotors. These gases form a boundary layer that prevents intimate contact between the friction material and the rotor.If you want the holier look, use a ball mill. You can get the same look without compromising the integrity and safety that the Benz rotors afford.

Listen to JS, He posted a site on brakes the other day, I read it and it was full of great info.

Cross drilling in my opinion is worthless.

Slotting is the way to go I think.

Alon

Guess Benz should hire some other guys to design their S-class brakes!! Porsche should use them also!!

The cars that have "drilled rotors" from the factory aren't drilled. The holes are cast in the rotors. This helps reduce the cracking problem. I'm not sure about the new carbon / ceramic braking systems. Some may have holes. I don't know the process used to put them there.

If you still think drilled rotors actually improve braking performance, check out the big fast race cars. None use drilled rotors. If it helped. They would be using it.

I ran cross drilled rotors on my 5.0 Mustang for about 10k hard miles. They were counter sunk holes and I never saw any cracks. They are very cool to look at through the wheels if you don't have the dust cover things. Just don't try running these things on a track. You most likely will have cracking. Plus it costs more to tear up the cross drilled rotors. If you want them for the looks and only for street/auto-x use they're great. Get them cadmium? plated if you're going for looks too, especially if you show your car.

Anyone have track experience with the various brands of MB rotors?
Darryl
'91 190E

The site the BlackMErcedes (john, or JS) posted talked about why rortos were drilled in the first place, which was to allow gasses that could get between the syrface of the pads and disc and act as a lubricant a place to go so they would not act as a lubricant and reducing stopping power.

You guys should find that article he posted and read it. The information may surprise you.

with todays braking technology, the cross drilled rotors according to that article, are for looks only and do not make the car brake better.

It was really interesting.

Alon

I was reading the Carlsson tuning website and noticed they too use drilled rotors on their brake upgrades. Are the newer drilled rotors casted this way, as others have alluded, to prevent these stress risers I've read about?

I find it hard to believe if these are so disastrous a tuner of their integrity and reknown would use them.

Just curious,
Brian W.

Well there are differences in how certain manufactuers make there discs. I know many companies drill holes afterwards. This is not smart, cause you do ruin the strength of the discs because they were never meant to be drilled. Now many high-Performance companies sell brake discs that are slotted and drilled built into the design when made. These discs describe what the S500 Sport wears.

Word of advice, if you take a cheap short cut, it usually back fires. Thats what many brake companies end up doing. My next change is going to use the Slotted and Cross Drilled rotors, but till then, the pads are just as important. And the EBC Brakes Green Stuff works great! Almost no dust, no fade problems due to the pads, last pretty decently, and no sqealing!! Alot from a set of pads.

Check out the pictures of the McLaren rotors.

I know this may be an extreme example, but aren't these drilled rotors? I had the opportunity to see the expose on the building and designing of the McLaren F1 on speedvision and remember them talking about the brake system on this car, and if I remember correctly, the brakes at each wheel were over $25,000!


http://www.peachparts.com/shopforum/newreply.php?action=newreply&threadid=14289

What a car,
Brian W.

oooops!
 

Try this:
http://www.angelfire.com/ca2/rpmscars/mclaren.html

It was mentioned before, but to re-iterate, unless the holes are CAST during manufacturing, "drilled" holes weaken the rotor unless re-tempered which is costly.

The ATE PowerDisc is a good compromise, because it is grooved (for gassing) to a depth that tells you when to replace the rotor, ventillated cast-iron to shed heat, and TUV approved.

Good luck,

:-) neil

S600 AMG Brake Rotors
 

I saw an S600 AMG at my dealer today, it had drilled rotors.. Although not as extreme as most (very sparsely drilled), I am inclined to agree with MB DOC. I Had a set of rotors drilled on my dads 1997 3000 GT VR4 T/Turbo AWD and they worked out great. Too many reputable tuners and ultra high caliber manufacturers use drilled rotors for them to deserve the rap that they are getting in this thread.


Jason M.

Have YOU checked a race car lately? The last race I saw (ALMS, Laguna Seca '00) had GT classed Porsches/Bimmers running huge drilled discs. Guess they aren't "big fast race cars"?