LTC Z06

Just starting receiving SAE papers and got one where some GM engineers test drilled vs. non-drilled rotors for performance. The did not test stopping distances or a slotted rotor. They tested for fade, cooling, and wet braking performance. They referenced the conflicting information you get from brake manufacturers and the internet forums. They did not state the cars but from the descriptions one is a vette with drilled and non-drilled rotors and the other one is a 911. They did simulated street, race track, and dynometer testing. Some of the conclusions will surprise you. Bottom line: Drilled brake rotors do slow a car down better and it is exponential as speed increases. Drilled rotors have less fade. They could not confirm if this is due to out-gassing but it is due to mechanical friction and scrubbing of the pads; and cooling which is also better. They did state that pad and rotor life is twice as short compared to non-drilled rotors. They were not better in the wet.

outnumbered

So they are saying that drilled rotors scrub pads also?I thought that the slotted were the ones that scrubbed the pads.

haljensen

Real life testing and results instead of theories? I'm impressed!

Scissors

So the C6R has drilled rotors, yes?

LTC Z06

I'm sure they do, they did show a reduction in performance if the holes became clogged.

LTC Z06

They only tested iron rotors. I think the C6R has carbon ceramic.

LTC Z06

Also, they tested semi-metallic and organic pads. They experience rotor warping and here is their conclusion. The rotor does warp when it is very hot, not a design flaw just the nature of the material, this warping does make the pad deposit material on the high spot. After cool down the felt vibration is due to the deposits, so it's a combination of true warping and deposits.

outnumbered

Most of the people I know that track alot take spare pads and rotors.They buy the Gm performance equip form dealer for their C5Z06's.They say they are inexpensive and they just throw away when they go bad.They claim even the real good stuff will only take so much.

Joe0121

In Nascar at Martinsville roters and pads are good for one race and sometimes not even that.

racerns

Good info
Could you provide the SAE Paper number? Thanks

Scissors

But the material would not change the basic aerodynamic properties of drilled holes. If they cool iron, they'll cool carbon ceramic. And if they scrub one kind of pad, they'll scrub another.

LTC Z06

I would assume so also.

Verrückt

It depends. Carbon brakes use carbon fiber pads which are very hard.

They will not distort as much as a normal pad will. When pressed against the rotor, you'll get less "cheese grater" (for lack of a better term) bite where the pad will distort into the holes/slots.

I predict that the benefit of slots and holes will be less on full carbon brakes simply because the pads are harder (compared to normal pads) and the rotors are softer (compared to normal iron rotors).

One of my buddies works on a Formula 1 team.

Their carbon brakes have no slots/holes

outnumbered

Isn't true that they make pads that don't emit the gas which is the main
purpose of the drilled rotors to release the gas?

EuG

I wish they'd test against sloted rotors as well

Also I'd be curious to see the numbers quantifying just how much better the braking and fade performance is.

Half rotor/pad life is serious trade off

LTC Z06

The first use for holes was weight reduction, then outgassing, now we have new info.

outnumbered

so outgassing was discovered by accident

LTC Z06

The fade test was very complicated. They had sensors and devices all over, they measured everything. Most of the paper is in engineer speak, so I read the conclusions and reviewed the meat of the test.

Verrückt

Modern pads don't gas much anymore. The main purpose these days is for pad bite, pad cleaning (which slots do better), and weight.

FWIW, my brakes are drilled and slotted. I'm very happy with the performance and the bite, but I know they'll crack in due time.

I'll probably get just slotted when it comes time to get new rotor rings.

Verrückt

I'm quite interested in the test. Please provide more info when possible.