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I have a question on how to best correct a small problem I’m having with the S4 brake upgrade that I’m doing on my 81. I have the 993 rotors and S4 calipers mounted on the front and went to put my wheels on and they just kiss the PORSCHE raised letters on the calipers. I have 19x8.5 ET52 wheels on the front. Is it possible to get some kind of very thin spacer or use washers under the wheel to pull it away from the calipers? I swear it’s only a 32 of and inch to clear it. I have thought of grinding down the height of the letters but I would prefer not to if there is another option.
how about a picture of the wheels?
also did you fit spacer washers to the caliper mounting brackets this will center the rotors on the calipers?
some of those mounts might require a 2mm washer this will move the caliper in away from the wheel
Not a great picture but it shows the wheel with the old caliper. The car hadn’t settled when this picture was taken, the tire sits way closer to the fender normally.
On the rears I used washers to center the calipers but I’m using the adapter brackets for the fronts. The calipers and rotors line up great it’s just that the caliper is rubbing on the inside f the wheel. It just nicks it. I turned the wheel and the corner of the P letter on the caliper left a line on the backside of the wheel, a small groove. Just a hair too close so I need to move the wheel out from the caliper. There’s no way to move the caliper back.
As you've found brake upgrades and wheel changes have quite a bit more to them than offset. I did the ferrari F50 brake upgrades and had to do quite a few wheel measurements that included going back and forth with Fikse and Brembo on the same call several times. Brembo finally gave me the drawings for the calipers, followed by several rounds of calls with Fikse. They barely fit and probably won't fit with any other wheels.
another thing to think it mind is debris. While a few mm clearance is good enough to prevent contact, small rocks, and other road debris can get in there and impact the safety.
I’m going to give a 3mm spacer a try to see if it opens the space enough. It should. I take your point about debris. That was on my mind when I first saw how close the tolerance looked.
I’m going to give a 3mm spacer a try to see if it opens the space enough. It should. I take your point about debris. That was on my mind when I first saw how close the tolerance looked.
2 schools of thought, the space is so small that it would be really difficult to get something in there to begin with, but it is also a cast wheel center.
A 3mm spacer would would put his ET52 at ET49, wouldn't it?
Yes it would and he's really already too low on offset to start since an 8.5" wide et 52 is really a 911 fitment and not a 928 one. The 928 et on an 8" wheel should be 60-65 or at least high 50s (57/58) especially if the car is riding slightly lowered like the OP states.
So comparing what we're talking about to an ideal 8" wide et 60 wheel, being 1/2" wider means for the same offset the wheel will be 1/4" further in and 1/4" further out, or about 6mm. That's like an offset of 54. Now his offset is 52 instead of 60 so that's another 8mm out, now we're 14mm further out and we're talking about another 3mm spacer so a total of 17mm further out than ideal.
If the car is lower than stock, I think you're going to destroy your fender if you hit a mid corner bump that compresses the suspension at any type of speed. At a minimum you're going to need to roll the front fenders, but I would probably find a wheel that's a better fitment to the car and application.
On my '79, I've done something similar but am running the 993TT rotors with Big Blacks (GTS versions that are larger than S4) and the 928MS caliper adapters. My wheels are:
Front - 18x8 - offset 57 with 235/40-18
Rear - 18x10 - offset 65 with 295/35-18 and 15mm spacer
but being a convertible, my rear fenders aren't stock, so don't go by those #s for what will fit the rear of your car.
Fronts are great though and the wheel style I chose has enough clearance for the calipers. Here are a few pics so you can see stance and fitment. I tried to get you views looking down the side of the car for offset and a side shot for ride height setup.
I have a question on how to best correct a small problem I’m having with the S4 brake upgrade that I’m doing on my 81. I have the 993 rotors and S4 calipers mounted on the front and went to put my wheels on and they just kiss the PORSCHE raised letters on the calipers. I have 19x8.5 ET52 wheels on the front. Is it possible to get some kind of very thin spacer or use washers under the wheel to pull it away from the calipers? I swear it’s only a 32 of and inch to clear it. I have thought of grinding down the height of the letters but I would prefer not to if there is another option.
What year s4 calipers did you use? 87/88 are slightly larger IIRC.
03-03-2019 | 05:49 PM
S4 brake upgrade and wheel offset
