spjuvern

are ther any optinal front brake rotors or are it just porsche oem parts available

i thinking about the crack is very ordinary on the oem parts

dholling13

Don't know if I understand the question but I am currently changing to 928 GTS solid rotors due to spider cracks. I would recommend asking the Porsche PHD about your options.

Rickard 993 Turbo

Brembo,alcon,PFC or some big rotor names should have a kit for your car

Staffan

Are these bolt-on?

I have major heat problems with my front rotors on the track.
Have brake ducts with hoses pointing the air into the center of the disk.
If I ran full speed for more than 10-15 minutes a develope serious cracks in the disks. Just returned from Nürburgring where I developed cracks straight through. My discs only last about 7 hours of driving, the teams I talked to running 24 hour races doesn't have to change their discs during training, qualifying and race (total 26 hours).

Had an expert looking into the problem, he claims that the great leangth (or width) of the hub that causes these cracks. The disc tend to bend outwards from the heat creating cracks on the outside of the disc. His suggestion is to invest in hubs for floating discs which is my plan.

Another thing I will try is to fit 3.6 pads on my car (I am running 3.6 discs), heard it can be done by exchanging the bottom steal plate in the 3.3 calipers.
Not sure if this is a bad idea, perhaps someone has tried this?

cobalt

The 928 GTS discs are identical to the 94 turbo discs except they are solid face. I have both cars and the discs are interchangeable. Although the GTS discs are more expensive because they are not a common item. The cracking is an issue on all models that are tracked and use cast hole rotors. Even the 993TT with a separate smaller hub has the same problem. The cracks supposedly are OK so long as they do not extend to the outer edge. If you can find aluminum hats for the 964 T let me know I have been looking for a long time. I hear they can save as much as 4 pounds per corner which sounds high.

I am not sure modifying the medium S4 caliper with the plates from the big reds will work. The medium S4's use the same pistons and a slightly (10mm) smaller pad however the casting is actually smaller (narrower) than the big red so how this will adjust the pads placement I could not say for sure. You can pick up used big reds. I picked up a set for about $500 a while back.

dholling13

Staffan,

Just ordered a set of GTS rotors from Stephen @ Imagine, he has them in stock. No more spider cracks for me...

Drew

Staffan

Interesting, are they much more expensive than the 3.6 discs?

Anyone got the part number who is using these discs on our cars?
I do have PET, but just don't want to mess it up because I will have to order the discs in germany and pick them up on a saturday with no way of exchanging them during the weekend.
Perhaps I will do this next time instead.

cobalt

Staffan,

The part number is the same as the 94 turbo rotor with a 928 prefix. So it would be 928.351.045.01 and 928.351.046.01 These will have the same surface area as the 94 turbos to accommodate the larger 58mm x 132mm pad.

Although the 928 S4 used the same calipers as the 91-92 turbo they used a smaller rotor so there is no solid rotor that is identical to the rotor used on the 91-92 turbos although the GTS ones will work fine.

Geoffrey

The solid disks will still develop cracks over time. What pads are you running? On the 964 Cup cars (964 Turbo disks), we get a full season out of the disks (they are 5-600lbs lighter), and on my 3000lb turbo, the 993tt rotors lasted a year with Pagid yellows.

lwilkins

I have used the Diversified Cryogenic treatment on my rotors, and they seem to last longer than the untreated rotors. I can't give you definitive days of use, but the treated rotors last a long time. My current set of fronts has lasted over a year, on my 3150 lb + race car. That's probably 16-20 track days, so far.

Most of this is on two tracks that I don't consider to be particularly hard on brakes, Texas World Speedway and MotorSport Ranch. I've definitely been to other tracks that are harder on brakes, so perhaps this is not representative of your situation.

Or maybe I'm not braking hard enough....

dholling13

I am running hawk blues on my car. One DE and the rotors took a beating. The rotors had less than 3k street miles on them. I might switch to performance friction pads next because the hawk blues are so violent on the rotors...

Staffan

I'm currently running Carbopad GT, I have tried "everything": blue, orange and yellow Pagid, PFC, Hawk and Carbopad. Overall the yellow Pagids works best for me. I believe my car is in the 2750 lbs neighbourhood without fuel, perhaps a little less.

graeme36s

All very valid comments and interesting that the 928GTS fronts discs can be fitted. I can't recommend a solution but just offer some thoughts. At least with the drilled discs you get to see the degredation of the disc. With the 928GTS disc you might not so obviously see the disc cracking and therefore the worst case scenario could be the disc exploding. (just a thought).
Personally I would try and aid cooling. Its no good blowing air onto the inner side of the disc, we used to make back plates for the disc with a tube welded to it and piped to the front PU air ducts. At least this way you blow the air through the centre of the disc and help cool it more evenly. Also do a slow down lap giving the brakes a chance to cool off a bit before parking it up in the pits or the paddock. That said I raced a 996 supercup car in 04 and we needed new discs after every weekend in the British GT's.

dholling13

The reason for my switch is a close friend races a 964 c2 and has had the same rotors for 2 years and after 5-7 races a year...

38D

I ran a solid Colman rotor that Dan Jacobs got. Even those would crack in ~3 race weekends (but better than the holey rotors which would last like 1 weekend!). The 500+ lbs less in the cups makes a huge difference in rotor longevity.