BC

The caliper sitting on the steering knuckle that is. Or shall we call it a hub carrier.

Tom in Austin

One more piece of the puzzle ... I had a pair of GTS rotors ... and measured the backspace dimension to the hub surface. Lindsey Racing in OKC sells alloy hats (for $295, IIRC) that will achieve this exact same backspace dimension with 993 TT rotors.

They characterize these as being for 944T Big Reds, but knowing the backspace, I am very confident that they can be used wherever GTS rotors can be used.

I asked them about re-using the mounting bolts and they said this acceptable and it was not required to replace these items.

Hope that helps!

sportscarclassics

Do you have a link to Lindsey racing?
Thanks

BC

Thanks Tim. I recieved a link from a helpful lister about LR's rotor hats.

They are 299.00 now. 150 dollars. Thats about what my design was going to cost if I made 6 for myself.

BC

But if I made 20 it would be 90 dollars a hat, 180 for the pair then.

Anyone else BTDT?

John Veninger

Brendan,
Will they be "floating" hats.

BC

I was thinking about that. Thats a great point, because Floating would mean there would be more room for expansion - the aluinum hat and steel rotor have different rates of expansion and there could be stresses not previously mentioned here.

The holes in the rotor that are used to fasten it to the hat must be oval to work with the floating system. I'm nont sure that the stock 220-240 dollar 993TT rotors are available with the floatting holes.

BC

I'll take my 993TT rotors aprt and see if the mounting holes are oval. This site is pretty cool:

http://www.zeckhausen.com/StopTech/consumables.htm

Dennis K

FWIW (and I don't know if this helps clarify things or makes it worse) but my car runs the Devek 4 wheel Big Red kit. On the fronts, it has the 993TT Big Red front calipers and uses the 965 (964T) single-piece cast-in hole rotors.

If 993TT rotors have a different offset, I don't see how'd they'd fit . . .

heinrich

I emailed Dave Roberts of 928 Specialists this morning asking him these questions, haven't heard back from him. When he replies I'll post it here.

BC

The 993 TT rotors stock will not fit with the S4+ hub that can simply have S4 or GTS calipers bolted straight on. In this case, we would need to use a different rotor as estimated earlier, or use the hats with the offset I have designed and will use on my 89.

With the 993TT rotors on an EARLY car with the GTS calipers on thier respective ADAPTORS, these adaptors are made with the offset to USE THESE 993TT rotors as they come.

Thats the answer to this burning question.

I have found that 332x32mm rotors are available just without hats in all different brands. See the link I noted above a few posts. So that would/could require yet a different hat for working with our systems. All very interesting.

Saving weight, as its spinning, and hanging off the front axles (or rear) is a very good idea.

Having taken all these pieces out the boxes yesterday, they are all very heavy. Saving weight in this area would seem very, very important. I currently have S brakes on the 78 - and the car will have about 500 or 550rwhp when fully sorted and tuned. Maybe the S-brakes could handle it. I don't know yet. No ABS.

heinrich

Got it and thanks Brendan - ys those suckers are very very heavy and huge though drilled. Interesting! Anyone want to trade my 993tt rotors for their GTS ones so I can instal my Big Reds onto the S4? They are *very* lightly used. I have another set that I'll use on the '85/6 with 80 spindles and adapters.

BC

So, therefore, I will still be making these for those S4 owners or others with complete S4 suspensions that choose to have Big Brakes on the front of thier cars, and wish to use the 993TT rotors, and (I will check that earlier link) other rotors like them that you can be SANS the hats.

John Veninger

Brendan,

Do you know if even larger rotors than the 993TT use the same mounting hats?
So if someone was to upgrade to F50 calipers with larger rotors.

BC

Boy that would be cool. I think there is a limit somewhere. The adaptors would be the big deal - the adaptors for the caliper to steering hub.