For those who have replaced their foglights with brake cooling ducts...

Did you also remove the 968 air scoops that attach to the A-arms? Or, did you keep them intact? Do the bottom mounted air scoops interfere with the flow of air from the foglight mounted air ducts?

I ask because I removed my 968 air scoops when I had brake cooling ducts installed, and I recently found that I have to replace my rotors. They are Zimmerman drilled; and the cracks are now connecting the dots, and extending out to the edge of the rotor. The rotors have 9 DE events on them...3-days at VIR, 2-days at Pocono and 4-days at Watkins Glen.

I'm wondering if this is partly due to removing the bottom air scoops and relying only on the new foglight brake cooling ducts...Or, is this just normal wear and tear?

I can't say for sure, but I'm pretty sure my rotors lasted me almost the entire season last year; and now they definately don't.

Thanks,

 

Jay,

Same problem on my race car with the x-drilled rotors. Your car weighs considerably less than mine (mandatory 3300 lbs w/ me aboard), so you'd think it wouldn't be as hard on the brakes, but your turbocharged car is also way more powerful than mine.

We switched to slotted rotors up front and things are looking very good after several races this Spring, which includes practice and qualifying runs, etc.

Talk to Junior.

 

Thanks, Richard, I will.

Jason

 

Jason,

Search some of the other model forums here. For instance, the 993 forum. Seems a lot of those folks who actually track their cars (AX, DE, etc.) stay well far away from Zimmermans.

No axe to grind with Zimmerman from my end....

 

Is it Zimmerman or cross-drilled rotors in general that a prone to cracking?

 

Seems a lot of those folks who actually track their cars (AX, DE, etc.) stay well far away from Zimmermans...
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Hmm,

I might also become one more of those converts...

In the mean time, I've decided to try OEM drilled rotors that are 'FROZEN' , from the Frozen Rotors Company, and will see how they work...not too much more for the process, so I feel it's worth the experiment.

Jason

 

The latter.

 

From what I've read here and in other forums, the aftermarket cross drilled are just that- drilled (after the rotor is cast), and the OEM cross drilled have the holes cast in from the git-go (hence, they are not really "drilled"). The theory, or so I read it to be, is that the drilling after casting leads to quicker cracking because your futzing with the material after it is already cast- and this premature cracking is supposedly more evident with aggressive use. The arguement for cast-in holes is the hole is made at the same time as the rest of the rotor and is therefore more structurally sound. Dunno. I'm just a biologist.

Anyway, the consensus that I have seen is to stay away from cross drilled for aggressive use. Additionally, I have seen that if you must have cross drilled, go OEM as they are cast and not drilled.

Please take what I say with a grain of salt- I am just relaying what I have read from multiple sources. I do not race or track, nor do I drive what I would consider aggressively. I just spend a lot of time reading posts in the other model-specific forums (particularly the 993 one). Also, I don't have a blown monster 968 either- run of the mill engine for me.... Maybe someday....

 

I'm just a biologist...
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So then, pleas explain why mosquitoes (sp?) chase after some of us; and not others!!

Jason

 

Actually an industrial microbiologist - I just gave you the abridged version! No clue about the skeeters! Perhaps those that weren't being chased had Off! sprayed on?! I've also heard that going outside after just showing (and having applied various toiletries such as deodorant and cologne) attracts more bugs than if you had just gone outside all sweaty and dirty.

That's what I tell my wife when I don't shower- but she never buys it!

 

That's what I thought!

 

We experienced the cracking problems on the 968 with OEM (viz., cast) rotors. So far the slotted rotors have worked very well.

Experienced no similar problems with OEM rotors on my 911.

 

I gave up on all varieties of cross drilled rotors a long time ago. No noticible benifits, extra cost, and reduced life - not a good combination. I tried slotted rotors, and didn't see a benefit there either. I also tried cryo treated rotors and didn't see any improvement in wear. In fact, the worst crack I've ever seen was in a cryo treated rotor. Now I just use regular unmodified rotors, and get great braking at minimum cost. Very simple.

I do have cooling hoses routed in from the fog light openings, which I would highly recommend for a race car, especially if you're running without the stock cooling scoops.

 

Jim,

Did you keep your stock cooling scoops, or did you remove them?

Jason

 

I lost mine when I went to the Charlie Arms. At that time they didn't have the mounting points for the stock scoops. With the ducting through the fog lights I don't miss them.