Blank or Cross Drilled Rotors?

[jevs]

Any opinions for a Stalker XL? The opinions are all over the place on the net. Front and rear rotors are 12.75" with 4 pot calipers.

 

Even if I just wanted Cross drilled for the looks, are they going to crack on me the first time I put the car on a road coarse or autocross?

 

Blank is cheaper of course, but cross drilled is not really much more money depending on brand or lack of brand.

 

I don't want to do anything negative to the car.

[scannon]

I've had a set of the cast hole type show massive micro cracks after a couple of years of street and track use on my Miata. Since then I have only used the blank ones.

 

If you go with the drilled type make sure the holes are cast in rather than drilled. The drilled disks are more prone to cracking than the cast holes.

[xcarguy]

I run drilled and slotted rotors on both front and back; Wilwood on front and aftermarket Grand Am GT on the rear. After a year and a half of tracking my car, no issues with cracking. Pads are still at 80-90 %. You’ll more than likely NEVER overheat the brakes in these cars . . . . too light.

 

Front: http://www471.pair.com/stalkerv/gallery2/main.php?g2_itemId=9640

 

Back: http://www471.pair.com/stalkerv/gallery2/main.php?g2_itemId=9345

[James A]

Unless you are trying to lighten your rotors, there is no need to drill with modern brake pads. We have never had a single issue with braking on the race car where we must run the small front rotors and solid disc or the street/autocross/DE car that has undrilled upgraded fronts. And we always out brake everyone around us. Just no need for slots or holes on these cars in terms of braking performance.

[toedrag]

I'm a fan of blanks/plain. If you have a Napa store near you, you can get theirs which have a lifetime warranty. I think Raybestos also does lifetime warranty on some of their lines..

 

Some track people I know will buy the cheapest rotors possible from Rockauto and just treat them as consumables.

[Mondo]

The holes do look cool though;)

[jevs]

I am getting some slotted and drilled ones. What the heck. Not much more than regulars.

[Klasik-69]

I agree with Shane, these cars are too light to make this an issue. While I was tracking my Z06 (3150 lbs) I used DBA-4000 rotors which are blank rotors while others ran their stock Z06 drilled & slotted rotors, and all had issues with cracks and even total rotor failure. On these 7's, & Stalkers, braking is so light it doesn't make any difference. If you're doing this for looks, who looks at rotors ????

[jevs]

I agree with Shane, these cars are too light to make this an issue. While I was tracking my Z06 (3150 lbs) I used DBA-4000 rotors which are blank rotors while others ran their stock Z06 drilled & slotted rotors, and all had issues with cracks and even total rotor failure. On these 7's, & Stalkers, braking is so light it doesn't make any difference. If you're doing this for looks, who looks at rotors ????

 

I am doing it because I like them better (yeah looks), they are zinc plated, they might have some insignificant benefit (save a couple ounces, etc.), and it was less than $60 difference for the set of 4. Maybe they will look nice longer.

 

I was not looking for a reason to use them. I know they aren't needed. I was just making sure there was not a real good reason against using them.

 

They are bought now though We will see how they hold up.

Edited August 26, 2014 by jevs

[RGTorque]

same drilled rotors and pads since i got my car in 07. no cracks or add wear. i have willwoods btw.

[ecarte56]

On a fast track with slow corners, the rotors might get pretty hot, even on a 7. A fellow Stalker reported 1000 F on his rear rotors. The front rotors work harder but the rears do not get as much air flow.

 

You can estimate temperature increase per braking event using conservation of energy. Fred Puhn has a recipe for the calculations on page 11 of his Brake Handbook: http://www.scribd.com/doc/235504442/Brake-Handbook-Fred-Puhn

 

I ran the numbers for my car. A single braking event from 100 to 40 mph would yield an average rotor temperature increase of 190 F. 140 to 40 would give an increase of 407 F.

 

Paul M

[jevs]

On a fast track with slow corners, the rotors might get pretty hot, even on a 7. A fellow Stalker reported 1000 F on his rear rotors. The front rotors work harder but the rears do not get as much air flow.

 

You can estimate temperature increase per braking event using conservation of energy. Fred Puhn has a recipe for the calculations on page 11 of his Brake Handbook: http://www.scribd.com/doc/235504442/Brake-Handbook-Fred-Puhn

 

I ran the numbers for my car. A single braking event from 100 to 40 mph would yield an average rotor temperature increase of 190 F. 140 to 40 would give an increase of 407 F.

 

Paul M

 

How big were their rotors? These are ~12.75" with Wilwood 4 pots. (RX8 sport suspension rotors basically)

[toedrag]

On a fast track with slow corners, the rotors might get pretty hot, even on a 7. A fellow Stalker reported 1000 F on his rear rotors. The front rotors work harder but the rears do not get as much air flow.

 

You can estimate temperature increase per braking event using conservation of energy. Fred Puhn has a recipe for the calculations on page 11 of his Brake Handbook: http://www.scribd.com/doc/235504442/Brake-Handbook-Fred-Puhn

 

I ran the numbers for my car. A single braking event from 100 to 40 mph would yield an average rotor temperature increase of 190 F. 140 to 40 would give an increase of 407 F.

 

Paul M

 

And do you happen to know how his car's brake bias was set? Maybe there was too much going to the rears?

[xcarguy]

same drilled rotors and pads since i got my car in 07. no cracks or add wear. i have willwoods btw.

 

Roman, are you no long 'evil'? :rofl:

[ecarte56]

I believe that car has 10.75" Wilwood rotors and Dynalites on the front, and 11" GM rotors w Dynalites on the rear. You can find the 2012 report that John posted on the Stalker forum. He reports 900 F front, 1000 F rear, bias adjusted so that the fronts locked just before the rears. The temperatures were measured after stopping the car; peak rotor temperatures would be higher.

 

I made a spreadsheet when I was setting up my own brakes. I estimated that weight transfer during braking could easily be 70% or more to the front tires - depending on grip. So far my testing has confirmed it. That means the front brakes have to convert 70% of kinetic energy of the car into heat, while the rears have to do only 30%. Since the rear rotors are similar in weight and surface area as the front rotors, that says something about how much better the air flow is over the front rotors.