Huh? The rotor will hit the rotor? The S4 calipers will not bolt on. You would have to grind a heck of alot more than 2mm off to get them to bolt up. The calipers were bottoming out on the rotor and they still had about 3/4" before they touched the adapters.

The S4 rotors are what I need. I have already tried it and it works. I think I can fabricate an adapter to be able to use these rotors with my s4 calipers but the pads don't cover the whole disk. Far from it. So I think the only advantage there would be the increased leverage from the larger diameter. I don't know if its worth machining new adapters for that.

 

Mark,
I checked them, I did not grind anything off of the calipers. I am using calipers off of an 88 S4 and a set of rotors that I bought from Roger.

Fabio,
I am not sure the rotors are the exact same one you have. Is there a parts number somewhere on yours? I may be able to remove the wheel tonight and check for a parts number if it will help, but I am getting on a plane for Mexico at 6am tomorrow.

 

Shawn thanks for the thread ... now I am interested in what adapter you can make to fit your S4 calipers to the 993tt rotors, as this is what I would have to do to use my 2 sets

 

No worries. I think I know whats up. Enjoy your trip.

I think I can make an adapter to fit the S4 calipers to the 993tt rotors on an OB spindle, not an S4 spindle. The adapters you need are just spacers I think. Isn't that what Mark Kibort is doing?

 

How is this project going?
Any updates?
Thanks

 

anyone know the difference between S4 brakes and baby blacks on a 968 ? talking front calipers and rotors only.

 

I have 993TT rotors on my 87 s4 5spd I drilled some 3/8" X 1" aluminium flat bar to match the bolt pattern on the caliper and spindle for spacers. Then had to die grind the inner edges of the caliper to clear the larger rotors as per MK's thread. Took about an hour to make the spacers and grind the calipers to fit. You will need longer caliper bolts to compensate for the added thickness of the spacers.
I bought mine from Porsche but you can probably get them elsewhere much cheaper.
Great cheap up grade. Makes for better pedal feel under hard breaking.
Only problem is the rotors cracked all to hell after three track days, I would try and get slotted rotors if you track the car.Other wise I'm sure the drilled rotors will be fine for street use.

 

I had the adapters made. They work great and the big rotors look great too. I'm getting ready to make a few more sets for my other cars. PM me if you want me to make you a set while I'm at it. You do not need longer bolts for these adapters.

 

How did you address the radius issue with the larger diameter rotors ?(322mm, which is the same as GTS or 965 rotors like I use ). the S4 caliper can not fit the larger rotor, due to its smaller radius accomidation design. (unless you dont mind the pad hanging over the edge of the rotor, and the adapters positon the caliper this way)

the adapters you have made are different from the ones generally made from the custom shops, as it allows for the use of the 993TT rotors, right? (just a different offset)

mk

 

Mark,

The calipers fit the rotor well and without modification. There is only one small part of the pad that isn't contacting the rotor and it is at the top center "point" of the pad. It is only hanging over by 1mm and it is a pad area that is only a few mm wide. Not enought to worry about and certainly not worth grinding on the caliper in my opinion.

To answer your second question. They are similar in design and material but different dimensions. They will not work on an S4. They will only work with the early spindles.

 

its 2mm at the top, but i understand, you dont care if you have a little pad hanging over and wear that pad kind of funky as it leaves some material on the edge as it wears. I made my spacers to have the top of the pad meet the top of the rotor. the edge of the pad will be below the edge of the rotor by about 1-2mm, which is fine. these pads are the same exact pads that are used on the Stoptech ST40s which use the S4 as well, and are 13" rotors, so its a professional way to solve the problem.

Grinding the calipers by 1-2mm on the edges is an easy fix with an air tool, and a little longer with dremmel but really easy.

can you post the pics of the adapters?

I want to see if there is a way to get that hat on 993 rotor to work on the 84s, so that the offset can be an advantage for a .25" piece of steel that can be threaded for the side mounting caliper bolts and through holes to the hub with bolts. basically, moving it inward

mk

 

And this is what it looks like, 993 rotors, s4 calipers adapted to fit larger radius contacting ball joints.

New steel ball joints on the way!

Andy '83 S & 79

 

I have 2 sets of drilled big rotors I'll sell at a decent discount.

 

Andy, even if they hadn't touched the rotor you should change out the aluminum ball joints. It's a potential failure point and they were recalled by Porsche if I remember correctly.

Good morning heinrich. What brand are the rotors and what are their part numbers?

 

I have to say I don't like this mod, even if it didn't hit or touch it is way too close to the disc, imagine when the disc gets very hot and then you stop the car. Think about the heat soak and what about the rubber boot with all that heat?