PM sent for details.

BTW, you mentioned doing this on your 78 and the rotors hitting the lower ball joint. Have you changed your lower ball joints from the stock aluminum parts to the newer steel parts? If not, I highly reccomend that you do. It will not only be safer ( there are pics somewhere on Rennlist of wrecked 928's due to failed aluminum lower ball joints ) but the steel ones are slightly smaller and will give you the clearance that you need. If you order the ball joints, be sure to order two extra (large) eccentrics. Otherwise you wont have the parts to finish the job. Also, be sure to ask if the ball joints come with new nuts. If not, they are 12mm X 1.5 lock nuts. Ask me how I learned this. The hard way of course.

BTW, for those reading along at home. I switched to S4 rotors and everything fits. I'm still waiting to get more details from tlsmith regarding his swap. I would really like to utilize these really expensive (and pretty) rotors. If anyone is looking for some, there are holed rotors for the front of an S4. They are made by Sebro.

 

That just puts one at risk for STD s.....

 

Yup I have the new steel ball joints. They were installed at the same time as the brakes. I had hoped the newer ones would help. Even when I mounted the adapters correctly, and changed over to the newer ball joint, I still could not use the OEM S4 rotors off my parts car. Once the screws in the rotors were tightened down, the rotor made solid contact against the lower ball joint, negating the need for brakes. :0 The wheels would not turn. The 993 rotors have a shallower cap, thus moving the rotor slightly father away from the body of the car.

 

Tim,

I have read your PM as well as this post. I still don't understand how you were able to use S4 calipers with 993tt rotors. The diameter of the rotors are different. The way you described mounting the adapters wrong would only move the caliper more toward the engine bay or less , not further away from the axis of the spindle which is what is needed to use the 993 rotors ( as far as I can tell). Where did you buy these adapters? I hope I'm not sounding like I'm badgering you. I'm just hoping you are correct so that I can use my rotors.

Thanks

 

since the offset would have to change , I would think that the adapter is different. but of those adapters are used, the S4 rotors wont work either (if they are designed for the 993tt )

Also remember that you need to dremel out the S4 calipers to fit the 993, 964 or GTS rotors, as they are all 322mm. To use the S4 calipers and basically create GTS brakes without the expensive pads , you need to use the spacers I made for mine to push out the caliper on the radiaus.

mk

 

Or S4 spindles with GTS calipers and different size hats.

 

So I have an S4 with S4 brakes. I have 2 sets of 993tt rotors as well as a set of big reds. What do I have to do to use the 993tt rotors Mark? where does one get this spacer?

 

To use the 993TT rotors, you have the change the hat offset. The original 993TT hates make the rotor stand too far to the outside of the fender.

 

You are correct, all of my issues were with the offset of the rotor surface from the car, not in the diameter of the rotors.
I am at work today, but when I get home I will compare the S4 rotors with the ones currently on the car. I only remember noticing that the rotors were slightly thinner and had shorter caps (more offset outward).
I will also see if I can find the part numbers off the current rotors to verify that they are indeed the same as the ones you are trying to use.
I got my adapters from Roger.

edit (added): I don't remember dremeling out the calipers, but won't swear I didn't.

 

Understood Brendan but Mark seems to have done it without hats?

 

For extra assurance with ball joint clearance, make sure your front wheel bearings are still good.

What wheels are you using? I've got manhole covers on mine and had to buy spacers so they would clear the calipers.

 

Fabio,
I have checked the rotors on my car, they seems to be the same diameter as the S4 ones I have laying around, but I did not remove them to get a proper measurement. I did not see a part number as i recognize them. Maybe it is on the back somewhere. Here are the markings that I could find.
"1520 (oz) 27826 min th 30 0mm Made in Germany 66". They look exactly like the picture you posted above.

I am going out of town tomorrow morning for the next 8 days, so please feel free to call me tonight if I can help in any other way.

 

Mark is not using 993TT rotors, and he is spacing out the S4 calipers to work with (I believe) 965 rotors.

 

Here is what he did. https://rennlist.com/forums/928-foru...ght=big+brakes

 

if you are using S4 calipers, you cant use the 322mm rotors as they will hit the rotor BAD. you need to dremel off about 2mm of material at the edges. when they bolt on they will wedge the rotor to the caliper. Iguess if you drove it for a while it might grind itself down, but that would be pretty ugly.
mk