John Veninger

I'm not worried about that part, just if the hats can go with the upgrade .

BC

If the upgrade were for a porsche, the hub-centric hat would need to very the same or very similar dimentions, but the offset could be different. If the larger rotors were more then 32mm wide, then maybe it would need yet another offset measured hat.

svp928

I maybe able to shed a bit of light on some dimensional questions about hats/rotors specific to 81-86.5 cars- I have a set of Devek hats and rotors for the front of my 85. The hat was designed to use a 13 in. (330 mm) dia 1.26in (32 mm) thick rotor made by Coleman racing ($159.00 on Coleman's website). This rotor uses 12, .250 dia bolts on a 7.00 in bolt circle. The hat is spaced to allow the use of a big red caliper( bolted to an adapter) with this rotor, on the stock hub. The caliper adapter bolts on where the orig caliper was, and the red caliper bolts to the adapter. this allows the rotor to clear the lower ball joint. The hat itself is machined from 2024 T6 aluminum round stock. 2024 is used because it has about 50% more tensile strength than 6061. From the face of the hub to the face of the disc is 1.230" (31.242 mm). The Coleman rotors are made for heavy cars- Nascar, 3400 lbs, so they work well on our cars and are relatively inexpensive. They may make one with the Porsche hat bolt pattern, as well.
Hope this helps a little.

Steve

BC

It does Steve. Thanks.

Your adaptors for the calipers - did you use early spindles or did your adaptors specifically come for your 85 spindles.

svp928

Mine are 81-86.5 specific. I believe Devek made some fo 78-80 as well.

BC

81 spindles are different then your 85 or even 82. The brackets most sell are for 81 and pre.

svp928

Hmmm, I guess I'm not enough of an expert to tell, other than these ones do fit my car. We actually made those parts for Devek, but there was always some confusion as to which year they started/stopped at. We made two different models, and two different offsets for hats- but I believe the hats were for -upto 86.5 and then 87-later. Forgive my fogginess- its been a while since we did them.

BC

Three different spindles as I can see. Pre 81, 82-86.5, and 86.5 to 95.

"We"? You still have the cad file for the brackets? Or the hats?

svp928

I own a machine shop. Only thing I know that's more expensive than a 928...I have drawings, just went and looked at them. One caliper adapter says "78-79", the other doesn't say- and that is the one I have on my 85. Devek owns the drawings, and it would not be right for me to release them, or make those parts for someone else, unless I get their OK first. I can tell you that the 78-79 is a very simple adapter, and I believe it was intended to allow S4 calipers to fit on early cars. Looks like 80-81 may be orphan, or maybe the 78-79 will work?

BC

I am not aware of any difference between 79 and 81. Same Brakes. They changed in 82 to "S" brakes, with a different spindle.

svp928

OOh, then perhaps these early ones will work. Are you working on your 78?

heinrich

I think a simple spacer with longer bolts would be good here. The twinturbo hat is about 1/4-in too shallow. Just add a spacer. Thoughts? Cheap and can be machined very reliably from mild steel?

Andre Hedrick

I have 993 cross drills on my '81 w/ S4 BB'

heinrich

MUST DISTINGUISH BETWEEN

993 TwinTurbo crossdrilled and
993 turbo and
993

The twinturbos do not fit, on anything, to my knowledge. because the rotor hat is 1/4-in shorter/shallower than S4.

heinrich

Andre are your rotors the 2-piece? If so they are twinturbo.