Cross drilled brake disc

[KAMAL]

I want to upgrade my disc brakes on my 1995 E420. Where can I get good cross drilled brake disc? Which brand should I buy? Has anyone did this upgrade and noticed any change in braking? Do I have to change the my stock calipers. And what about brake pads. Will the cross drill disc be compatible with stock brake pad size? What kind of things to look for this modification.

Please provide some input and advice.

Thx

[haasman]

Kamal

If you do a search you will find quite a bit of discussion on cross-drilled brake rotors. Some claim it is simply a visual and a non-performance item while others see their benefits. I have them on our 300E and have appreciated their qualities. New Mercedes are coming with them standard now.

I would consider installing front ones only. You do not need to change anything but the rotor. There are cross-drilled, slotted and a combination.

Take a look here for some helpful information:

http://www.raybestos.com/usa/rotors.htm#

Haasman

[yal]

Fastlane above has Zimmerman Cross Drilled disc for you...check em out

[csnow]

I vote against them.

Uneven rotor wear pattern led to bad performance over time.
Just unlucky? Perhaps, but I did try them on 2 different vehicles before giving up.

I am testing slotted rotors on 2 vehicles now, and they have been ok thus far.

Best of luck.

[DuckMuck]

Originally posted by yal
Fastlane above has Zimmerman Cross Drilled disc for you...check em out

WOW! that is brand new! they must have just added it...I've been checkin' that page pretty regularly, and just saw it!

[MRPerformance]

If you use your brakes really hard, such as at track events, I would recommend that you avoid cross drilled rotors. They WILL crack if subjected to rapid, extreme temperature shifts. This is true even on cars that come with cross drilled rotors, such as Porsche and Ferrari. I have a fair amount of experience in this area and I will not sell or use cross drilled rotors in most applications.

Besides, the improvement in braking performane is negligible. If you're looking for significant improvements in braking performance I'd suggest looking at different pad compounds or upsizing the brakes. Of course, even these ideas have a downside but it's not as extreme as having a brake rotor come apart...

MikeR
'93 190E 2.6 Sportline

Cross drilling was first done by a BMW race team that was trying to make a very specific type of brake pad work for them. The problem was gases that were being released from the pad under braking that were causing problems. To release the gas, the cross drilled. It looked cool (no pun intended) so people started copying them.

Since no street pads have this outgassing problem, the cross drilling decreases the brake capacity.

Think about it. A brake rotor or drum is basically a heat sink. The kinetic energy of motion is converted to heat upon braking. The heat is transferred to the rotor/drum and then to the surrounding air. This makes the rotor a container and conductor for the heat. Its mass and thermal properties determine how much heat it can contain and transfer. When you decrease the mass(by drilling holes) you are decreasing the amount of heat that can be stored by the rotor.

I'm sure that the BMW team took this into account when drilling and used a larger rotor with more mass so they had some to give up.

Summation. For your street car with streetable pads, cross drilling is strictly cosmetic.

Have a great day,

[TexasRedNeck]

You're getting some good advice here. But let me throw in my two cents.

All hi performance racing applications are going to have either slots or drilled holes. Cross drilled rotors are upsized to make up for lost mass.

Any change in your stock brakes are going to come with a trade off. Changing compounds will change the pedal feel, braking performance and rotor/pad longevity. Hard compound pads don't brake well until hot. Soft compounds fade with repeated hard braking. Changing rotors will only have an effect if you are running the car extremely hard, in which the larger heat sink/cooling effect will help keep your fluid from boiling.

If you look at NASCAR brakes, they are all slotted as they are not allowed to use oversized brake combinations. Other racing sports use cross drilled, but again they are usually way oversized, such as 13+ inches.

On my bike, I have "wave rotors" and very hard compound pads. You can't hardly stop the bike until you get the brakes really hot, but once hot, they're unbelievable. They're flat dangerous when cold, though.

Bottom line is this. Unless you are putting the car on the track, save your money for some better tires, which is where braking really counts.

Also, search on brake pads using the search tool. You'll find more advice and stories of adverse effects of changing from the stock setup that you can imagine. I tried aftermarket stuff and wound up with a squealing problem that caused me to spend twice the money because I re-did the work just to get rid of the squealing.

Stick with the stock stuff if you aint racin'. My two cents.

[haasman]

Whether you can use the benefits of cross-drilled rotors is for you, of course to decide, but I find the "cosmetic" comment troubling. If that were true then Mercedes, Porsche, BMW, Ferrari etc all are installing faux components on their 2003 automobiles.

I suggest that there is more to this topic than a fad. All brakes generate gases as a partial by-product of braking. To allow the gases to escape increases the effectiveness of the pad against the rotor, called venting. The well-known benefits of cross-drilled and/or slotted rotors include smoother braking, greater stopping capabilities, reduced brake dusting, excellent wet-weather braking and often longer rotor life, depending on use and pad applications.

I crewed for several Porsche race teams in the early 70's. The rapid adoption of cross-drilled rotors was met with mixed success: They stopped cars better, dramatically improved wet-weather braking and reduced unsprung weights. Race drivers reported initial brake application gripping as slower (cooler rotors) but also found greater braking effectiveness and fade resistance. These rotors were rapidly adopted across the board.

The original cross-drilled rotors often failed due to cracking around the holes. The second-generation cross-drilled rotors had chamfered edges around the holes that all but eliminated the problem and is what one sees now on all cross-drilled rotors.

The first street application by a manufacturer was the Porsche 930 (911 Turbo) in 1979. Porsche has continued to install cross-drilled rotors on their cars since. If they were ineffective, or worthless, why wouldn’t they have been removed years ago?

The standard Mercedes brake rotor is vented and is time and Autobahn proven so why bother to upgrade? Because there is a newer solution that companies such as Mercedes, Porsche, BMW and Ferrari all have adopted.

Will your use justify their installation? I see it as for almost the same amount of money as a standard rotor, you can improve your braking.

Haasman

[manny]

[QUOTE]Originally posted by haasman
[B]
The second-generation cross-drilled rotors had chamfered edges around the holes that all but eliminated the problem and is what one sees now on all cross-drilled rotors.

haasman

I read an article by Brembo about cross-drilled rotors.
In that article it was stated " if the rotors are cast with holes, there is no cracking problem ".
Unfortunately, many " tuners " buy regular rotors, cross-drill them, mark up the price, and sell them to an unsuspecting public ( at least until somebody sues the a.. off them.
I run Zimmerman cross-drilled rotors and love them.

[TexasRedNeck]

Yeah, but on a street car the real benefit is having big openings in the wheels so you can see all the pretty holes......... then you have to paint the calipers

[timreid]

MB pads are designed for your car, and do a very good job, but there are a few aftermarket pads that will enhance your braking performance and will present no problems.
One of the best ways to get full performance from your stock system is to add stainless steel brake lines, you will stop quicker. Stu Ritter wrote an article about upgrading to ss brake lines, in the Star.
enjoy your drive, timreid

[shanta]

Just to add my .02

I run crossdrilled rotors on my 94 E500 with Metal Master Pads and so far so good.

My rotors do have the chamfered holes. Mines are made by KVR Performance. They have applications for almost all Mercedes.