Turbo front brake differences?

[Tricky D]

What is the difference between the 78-80 front rotor and the 81-89 front rotor for the 911 (930) Turbo?

The difference in price is astronomical - in fact, I think it could qualify for the X Prize!

[jpnovak]

Floating vs non-floating. They are not interchangable. Floating are usually better for the track.

[Porsche virgin]

OK. As long as we're on the subject:
My car came with what I was told are 930 calipers. I can read the part number on them, but where can I find a list of OE Porsche part numbers to determine exactly what year/model they are from? I need to replace the rotors (front), as they are cracking near where it was cross drilled.

[jpnovak]

Either PET or use the search window of our host. Stoddard website also works.

[beepbeep]

Originally posted by Porsche virgin
I need to replace the rotors (front), as they are cracking near where it was cross drilled.

Hey, I think you're overreacting. Small radial cracks going trough holes is standard. They will appear as soon as you take the car to the track. As long as they don't propagate to other holes or edges and you discs are over minimum thickness, it's OK to use them.

I believe all 930 owners have those cracks ;-)

[89911]

Originally posted by jpnovak
Floating vs non-floating. They are not interchangable. Floating are usually better for the track.

To be more specific, the earlier turbos used the same spindle and hub as the narrow body car. These are the same rotors that will fit cars that are converted to turbo brakes. The price is so high because they only made these for a year or two and then went with a different spindle until 89. The last I looked they were $680/rotor? Thats if they even carry them. There are other ways to get rotors for these cars, namely by using the custom hats VCI or Rennsport made with there rotors.

[Bill Verburg]

Floating vs non-floating. They are not interchangable. Floating are usually better for the track

All true, '78-'79 are the multipiece floaters, after that starting in mid '80 they are 1 piece.

To be more specific, the earlier turbos used the same spindle and hub as the narrow body car. These are the same rotors that will fit cars that are converted to turbo brakes

Again true, but the difference is in the hubs, the early 930 floaters use hubs w/ the same o/s as the normal 911 and so are compatible w/ the narrow front fender cars, they then used a separate spacer to accomodate the wider 930 front fenders. The later 1 piece use hubs w/ a built in o/s and rotors to accomodate that o/s these are not at all comapatible w/ 911 front flares.

My car came with what I was told are 930 calipers. I can read the part number on them, but where can I find a list of OE Porsche part numbers to determine exactly what year/model they are from?

It is very rare that a 911 upgrade has oem 930 rotors or hats most likely you have VCI or similar hats and need to get matching rotors from VCI. Please note that rotors from vendor A may not be compatible w/ vendor Bs hats. Discuss thouroughly w/ the vendor before purchase.


These rotors are toast, small cracks that haven't propagated across holes or to the edges are ok

[Porsche virgin]

jpnovak, Thanks for the tip. I admit I have no idea what PET is, though.

beepbeep, I hope you are right! I'll have to check out some other vehicles with x-drilled rotors. It would save me a few bucks if I don't have to replace them.

I love this forum! Ten minutes and I get two answers to my question.

I hope you guys are around when I do my first valve adjustment in a few weeks!

[Porsche virgin]

Bill,
Thanks. I'm going to look at the part number tonight (which starts with 930...btw) to find out exactly what it is.
PV

[Bill Verburg]

Pictures of the rotor w/o the wheel would be helpful, from what I can see in the last pic they may indeed be oem 930 floaters.