Brake Rotors

[prooutlaw]

What are the best Rotors to run on an '83 930? Did all Turbos come with Vented Rotors or are those only Aftermarket ?
After a hard DE session the Car really shakes when the brakes are applied and are hot, it is fine after they cool down. By shaking i mean the whole car shakes like the tires are out of balance .
The Brakepedal does not pulsate like a warped Rotor usually would , What could be the Problem ?

[Bill Verburg]

What are the best Rotors to run on an '83 930?

oem's

Did all Turbos come with Vented Rotors or are those only Aftermarket

all 911/930 since '69 have vented rotors, I think that you mean mean drilled. All 930 since '78 use drilled and vented. Though drilled is a misnomer, they are actually cast in 4mm holes.

Sounds like a pad deposition issue. Shuddering all the time is likely to be bad struts, warped rotors or deposition. If it goes away when cold the deposition has been cleaned off or it is also possible the struts are bad but not being stressed enough...

Are you swapping 2 different kinds of pads for street & track?

[prooutlaw]

No , running the same pads limited Street or Track.
Even on the Track it works fine until the Brakes get hot then it shakes under hard braking .
After they cool down ( next session ) they are fine until they get hot again.
I'll have to check on the kind of Pads i am running .
Do you think the Pads could be the problem ?

[Bill Verburg]

Do you think the Pads could be the problem ?

Sounds like the most likely suspect

[Yargk]

Bill: I did a search and didn't find anything directly related to my question. My car might actually be done soon (for those who remember me, I might explain this years long project later and why it took so long) so I should start thinking about brakes. I remember you telling me that outside of endurance races, big reds were sufficient. I just wanted to make sure that this is the case. My car should make 550+ hp and it weighs probably around 2900 pounds (maybe a little less). I see lower hp new cars running around with 14 inch rotors and I really don't want to get the big reds to fade at the track and realize that I needed larger rotors. Although I'd also like not to have to spend thousands more on 14 inch brakes and 18 inch wheels. Thanks a lot.

[Bill Verburg]

It's not the calipers so much as the rotors, the 322x32 front and 322x28 rear 993tt rotors are fantastic but can be overdriven. The longer the race the more this is an issue. the 996 GT3RS, low 400hp 7 ~2700# is using the huge evo brakes in distance events and 330x34 & 330x30 for sprints.

You have an emmensely powerful car that is also middling heavy. For short 20 - 30 min sprints, w/ efficient ducting the 322 or 330s will be fine, after that ... it depends on other variables.

The other issue is that the 18" wheels can use wider tires that can better utilize increased brake torque, all of these things go hand in hand.

[prooutlaw]

Should i try harder or softer pads ?

[Bill Verburg]

Try something w/ a higher temp/ rating.

Pagid Yellow or maybe PFCs

[prooutlaw]

Bill, so you dont think the Rotors are the problem ?