I have a source for brake rotors who apparently purchases rotors from Brembo (front) and Zimmerman (rear) and has a shop in which he cross drills and slots the rotors. His price seems reasonable. Is there a downside to going this route as opposed to purchasing from a mail order supplier (ie; Mini Mania or Moss)? Anything to look out for?

Thanks for any advice.

 

I'm no expert here, but my understanding is that any holes in a rotor must be "cast in" or part of the initial creation of the rotor, not drilled in afterward... Zimmerman has a cast in hole rotor I believe.

My subjective opinion is that slotted rotors are the way to go, with better performance than cross drilled, which tend to crack.... Also, stock rotor aren't necessarily bad, and that good brake performance comes from good fluid and good pads, along with the rotors.

Cross drilled are cool and blingy for the show circuit, though..

my 2 cents worth

 

It sounds to me that you are taking a product that was not designed to be drilled and slotted and expecting the same performance as a product that was designed that way. Brembo sells drilled and slotted rotors, if thats what you want then thats what i would get

 

While OT from what was asked, I have posted a $200 reward for anyone who can produce proof of a rotor cast with holes in it. In fact another forum this fund was matche by another person making it up to $400.

Many pics have been shown producing blanks with rib reinforcments for future drilling and many pics of many brands of finished rotors with holes. But to date (after about a year of research and input) nobody has been able to show more than mold plugs and casting plates for the common rotor. Even the reports of some mfgs producing this elusive part have been cast in doubt by data from engineers. As one Brembo engineer put it; "great American mythe". At best it makes a great discussion on how it would even be achieved. A number of casting engineers called it all but impossible, and clearly not cost effective.

First hand proof of this cast in hole story comes by way of the mold pic and or the final rough casting with holes clearly visible. Not dimples, not webs, not anything but a view from one side to the other in a cast, un drilled manner.

 

Things to look out for:
How the hole pattern is developed, and who developed it? How are the holes drilled? (gang drill, one at a time, CNC...) What stress relief is used on the holes, and how big is it?
I'm sure I could think of a few more, given a lot of time
As far as downsides...I guess they would depend on the answers to those Q's.

 

I repeat

It is the material selection and heat treating process that are going to give you the desired qualities in a brake rotor.

If you just buy a brake rotor that was not intended to be drilled and slotted you are really rolling the dice on the results you get.

Yep....With refrence to your original question about this route and mail order............Actually there probably isn't any diffrence.....Billy-bob mail order supplier probably does not have the software to really engineer these products he just drills cool looking holes

Reputable suppliers are banking their reputation on the quality of application

 

The key issues here are where the holes are and how many. Any drilling is going to weaken the structure of the rotor.

Radiusing the holes is a good idea, but in fact at best you get two of the four sides of the hole. Think about it.

While the pros and cons can be (and have been) debated forever, the choice of doing them is up to the consumer. I don't car who's rotors they are, in due time you WILL develope cracks in them. The harder you run them the quicker it may become an issue.

Not everyone is going to agree with my position but it's stated here:

http://tceperformanceproducts.com/faqs.html

 

Hi All,

So... would you purchase the brand brake rotor from eBay? There are many fake car parts on eBay. How do you know if the parts you purchase are real? Has any one purchase the rotor from eBay?

Thank you.

UltraMINI

 

Last spring I bought the Brembo vented cross drilled/slotted front rotors along with the Zimmerman cd/slotted rear rotors off ebay for $200 with free shipping. I also added some EBC green stuff pads with stainless lines. I also spent about 50 dollars and put some ATE Super Blue brake fluid in the lines. The brake pads took a week or so to break in and feel good, so dont be worried about the initial feel. The stainless lines also felt good at first, but now I dont even notice it. As far as the feel of the braking, I think the pads helped the most. I can definitely tell they brake better when they are hot. I ride the Cherohala Skyway (a higher speed road just past the dragon tail) quite often rarely experience any sort of brake fade. Although when they begin to fade, its massive fade all of a sudden. Atleast thats how its been for me. All in all, I think the rotors for $200 dollars is a steal even if they don't perform any better than stock; it adds so much to your car's look, especially if you have aftermarket rims. I have had numberous people come up to me at a gas station and ask about the brakes. lol BTW, the complete setup including some professional installation help cost me around $450.

 

...yes, what about the two holes on the two inside faces of the rotor??? Makes me chuckle a little. Marketing folk

Solid rotors with aluminum hats More meat where we need it, less weight where we don't...and a possible heat sink...not sure about that one in practice.


Radiusing the holes is a good idea, but in fact at best you get two of the four sides of the hole. Think about it.

 

At the track a few months ago a guy in an E30 M3 was pretty bummed because at the end of the day, his new Zimmerman rotors had massive cracks developing. He also thought that they would be fine since they were 'cast'. Had to change them out for the stockers before he left...I could tell he wasnt too happy about that..:impatient

 

Cast in, whatever, drilled rotors have less surface area and potentially weaken the rotor... just avoid em is my opinion... I vote for slotted for best peformance gain.. about 5 years ago, I bought some cyro treated, which did last a long time....

 

Well... if we're voting, I vote for plain ole' rotors. Everything else is just useless bling.

If that's what you're after, then go for it, but don't come back pretending it was a performance mod like some of the others around here.

 

Regardless of how the holes got there the problem stems from unever thermal expansion and contraction. Drawing cool air past red hot iron can have that effect.

 

In the deepest, most logical part of my brain, I know that crossdrilling is ineffectual and maybe dangerous, but it just looks so dang cool. I've had crossdrilled/slotted Brembos on my 91 300zx for over a year with no problems but I don't drive it hard. Still cogitating on getting them for my MCS.

 

And in the end that's all that really matters. If you are satisfied with the results you don't have to justify your purchase to anyone else. If it weren't that way you'd all drive red cars.