tracksentinel

My wife's new Mercedes Benz comes with drilled rotors front and rear. Brake pads are ceramic. I would have to assume that out-gassing is important no matter what material the pads are constructed.

I have the drilled and slotted rotors on my HHR. I am not so much in love with them. They, along with the EBC ceramic pads do make the car stop way better than the stock set-up but I am no too fond of the vibrations I get when stopping hard. Not the same warped-out kind of vibration, but the vibration from the slots. It does seem that the more miles and stops I put on this set-up the better it gets so we'll see. Be nice if something on this car actually worked the way it is supposed to.

SS fan

We can always hope.

hyperv6

Sorry but I am just trying to provide the tech facts from the MFGs.

Here is Willwoods comments on this topic. I can provide more info from other MFG if you like.



http://www.wilwood.com/TechTip/TechFaqs.aspx#RT


Rotors Back to Top

Q: What's the difference between slotted and drilled/slotted rotors? Which rotor will be best for my application?
A:
PSlots or grooves in rotor faces are partly a carryover from the days of asbestos pads. Asbestos and other organic pads were prone to “glazing” and the slots tended to help “scrape or de-glaze” them. Also, cross-drilling and/or slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads began to break down at extreme temperatures. This condition is often referred to as “outgassing.” When it does occur, the driver still has a good firm brake pedal, but a significant reduction in friction. Normally this only happens at temperatures witnessed in racing. However, with today’s race pad technology, “outgassing” is no longer a concern with pads designed for racing.

So in the final analysis, drilling and slotting rotors has become popular in street applications for their pure aesthetic value. Wilwood provides rotors slotted, drilled or plain. For most performance applications, slotted is the preferred choice. With certain pad material, slotting can help wipe away debris from between the pad and rotor as well as increasing the coefficient of friction between the rotor and the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage; however, for street and occasional light duty track use, they will work fine. For more severe applications, we recommend slotted rotors.

Note the severe street use or hard track use most companies will tell you not to use a drilled rotor. Brembo also post this warning as they will crack and break.

I just recomend more people seek out MFG web sites and their faq and tech sections to get the most up to date and tech info. It is a little more accurate than most of the claims on many forums. Lets just say they have a vested interest in you having the best brakes possible to make you a repeat customer. They want you to know the truth.

Here is what EBC says http://www.ebcbrakes.com/cross_drill...d_rotors.shtml

VinceP

A recent sit down with a Brembo rep I recently had at a Cadillac ride & drive event said the same thing. They sell a ton of slotted and drilled rotors because they look "cool" (his words) but offer no huge advantage over smooth rotors. I am sure there is some difference but since I have not spent the extra $ for them I can only pass on word of mouth.

sleeper

interrex

If you look at all of these manufacturers products on their rotors, why would they put holes into their rotors? Corvette Ferrari Viper list goes on and on.

Greybeard999

So they can sell more because they "look cool"...... not to be confused with running cool.

hyperv6

they do many cars have fake scoops or powder coated calipers? Styling!
The reason they do is for styling and to give the image to many who think they work think they have racing brakes.

At one time it was true they out gassed pads and they also were there to help make the rotots lighter and provide less unsprung weight. For the most it was the unsprung weight.
Many of todays cars have large rotors that provide more than enough stopping power and wheels that are open. By drilling the rotors it gives a much more race looing effect.

Like the post above Brembo and most respected companies will tell the truth is asked and most even will tell you if you do track time or racing do no use a drilled rotor. Brembo makes some of the best brakes in the world for F1 and they have no holes or slots. Same for most other modern race cars today. Some may have a few slots to clean rubber away but that is all.

Just because something was true 40 years ago does not always make it true today.

If you like then for looks and styling there is nothing wrong with them but don't buy them expecting them to improve performance. as it is a false concept on a modern brake system today. Too many people buy them with the false impression they work. Often money wasted.

The fact is there are many false things out there in the performance area. I make a living and see it all the time. We still get people who think if they put a cam in a Chevy it has to have a Double pump 75 CFM Holley carb. Often the carb is way too big and hurts them more than helps. They add to that a cool sounding cam that the car is not set up to use properly and they have a car that could be a real dog or a pain to drive with the wrong combo of parts. Most of these problems can be traced to hey my buddy told me or false web advice.
THis is why on this topic I point out MFG web sites and what they say on this topic to back up the truth. I used to think the same thing in the past and learned from the MFG the truth. It may save many spending money for the wrong reason.

hyperv6

What he said is the truth and I have spent the money and other than looks there is no improvment. If anything they remove the heat sink of the rotor to remove heat. But on cars running 14" rotors on the street they still have enough rotor to handle street driving.

whopper

If you like them, use them, and enjoy them. If you don't like them, don't use them.

Come on guys - this is getting silly.