Yes, I thought you were saying that the rotor dia. you used was 304mm x 32 x 72 which is an off the shelf 993 (non TT)

 

Does anyone know what the threading size and flare-type of the S caliper is. I don't have a spare line to go by. Also how long is it (inches) to the main hard line and what is that connection?

 

with this adapter (s4 caliper) you can use the 993 rotor same diameter of the S4, but less of an offset (72mm vs 80mm S4) but then, you only get S4 brake rotors. with spacers, and if you can find a 993 turbo rotor that is 322mm, you could use that i imagine. this is an other discussion.

No as was said, this is for something totaly different. S4 calipers used on S spindles.

no, i just did the test. i just drilled 1/4" holes that had a nice chamfer and it centers it for installation and final position before you lock on the wheels and torque. i noticed that the rotor almost was self centering via the lug studs.

why would you want a 330 x 32 x 60 rotor?? this entire project is about the cayanne or VW tourareg rotor which is 330 x 32 x 69mm.??? I dont think there are 60mm offset rotors anywhere available. keep in mind this. with my 80mm offset rotors, there is not much space between the rotor and caliper and the wheel center! this is so close that I would even wonder about the clearance of the S4 set up with 993 rotors. certainly , any larger 60mm rotors would NOT work. thats 20mm outward vs the S4 set up and that surely would rub on the wheel center.

 

Mark,

Have you assembled the modified brake set up yet? Do the rotor, the adaptor and the modified "S" brake caliper fit well and does it improve the braking. If you have please post a pic or two of the completed project. How does the caliper look after it is modified? I have a friend with an 86 that we would want to convert if it works well.

Paul

 

The S4 rotor spec sheet states 77.3 mm offset. When it shows up I will mic it. I also just ordered brand new Cayenne front rotors 330x32x69 and I am asumming you guys are at least going to have to run 17's to clear even the S caliper on the 330mm dia. rotor. IMO, The centering rings are a neccessity on the Cayenne rotors and since I am building a Wilwood kit for them as well on the 944 hubs, I am going to lathe them out as well, no drilling involved. Heck if you don't have a press and table lock, I wouldn't attempt a precision located chamfer, 1mm off and you wasted your time. I will also see if the Wilwoods will rotate down on the 304x32x77 rotors since I'll have them in hand. The back of the Wilwoods will clear the steering knuckle on the Cayenne rotors, but not 100% sure about the S4 rotors.

I need to find an adapter to mate the 1/8-27NPT port to the 928 line to make it plug-n-play.....

 

im looking at this and wonder if there are any 330mm rotors for porsches that are the S4 offset of 80mm. certainly this would then be a much easier mod, with no machining needed, just drill 4 holes! rotor would be inward like the S4, and still clear the lower ball joint, as we are only talking 10mm closer (less than 1/2" )

 

i did a quick measurement and found it to be 80mm, but maybe its 77.3. Ill check tonight.

as far as centering. that hole 1/4" diameter with a chamfer will be easy to drill the chamfer is only needed to flush mount the top of the screw. the hole is exactly 1/4" dia. remember, we are talking 155mm vs 157.1mm. 1 mm on the radius. this will be very easy to center . PLUS as I said, when mounting the rotor with out the centering screw, the rotor was centered via the studs. there is maybe .5mm slop in the stud, rotor holes. so worst you could ever be off is .5mm, and that wouldnt be an issue, but i would want to try and make it perfectly centered too, thus the center screws holes (2) will be easy to locate and drill.

mk

 

Of all the posts here and other places , I have still not seen a difinitive answer to what would be the tallest rotor allowed that would still clear the lower B-joint at full travel. I saw the other thread that the 993 (304x32x72) rotor was purchased because the S4 rotor was too tall. I have those 7mm spacers that I am going to put between the hub and S4 rotor and do a mock-up if it's too close. I will go back to the junk yard and get a lower balljoint to check the clearance on full travel to confirm and post the finding.

 

O.K. cool about the set screws. From experience, folks want plug-n-play. Just to be 100% apples to apples, you are using a pre-87 hub correct? From the pic I have it looks like about another 17mm offset (diff between S and S4 rotor)

 

you want the set screws, just so the rotor doesnt flop around during wheel changes. but not totally required. heck, its just a mark and drill. the entire thing is not really plug and play as there still is some grinding work to be done on the caliper ends, which is not a big deal.

yes, we are using the pre 87 hubs stock on a 82 set up. the rotor specs are 60mm for the old rotors and the ones we are using from VW are 69mm. S4, from what i have seen is near 80, but if it is 77mm as you say, then thats fine. I certainly wonder if 17mm is enough for the rotors to rub on the lower ball joint. looks like about 1" of clearnace from the picture, but Ill check

before you posted something about the 1.5mm thicker rotor vs the old rotor on the 928. this is a good point. THIS means that the 69mm rotor as far as its surface position is concerned, RELATIVE to the older 928 rotor, is further outward by 1.5mm than we are thinking!!! not a huge deal with a floating caliper, but we want it to be identical as far as position. it also means an S4 rotor will be outer by 1.5mm too. (like a 77 -1.5mm= 75.5mm offset vs the 60mm of the thinner, 928 rotor) so, the S4 rotor is really only 15mm difference?

But, really, the caynanne VW rotor is not now 68.5mm offset, its 67mm offset. all of our dimensions were based on 69mm, so we are 2mm off as it it stands now due to the thickness difference of the rotor flange. we should adjust that drawing to reflect this differernce (assuming the 928 older rotor is only 5mm thick compared to the cayanne rotor of 7.5mm)

the fact that the entire track is outward by 3mm total now, is a bonus. (as long as you have the fender room!

make sense??

 

so the adapter at the thinnest part , should be 13.65mm not 15.15mm based on the rotor plate thickness at the mounting surface.

 

Yes, if you are re-using that heavily blanched rotor there will be a difference.

Only the Cayenne rotor is 1.5mm thicker at the hat flange. Unless the 928GTS rotor is the same (i haven't mic'd one yet) all the 944/968/928 hat flanges are 5.9mm thick.

This 3mm rotor offset (not hat flange) difference is very interesting as I have found that when The M030 rotors/brakes came out for the 944T's and 968's all they did was add 3mm to the hub face and stuck on the S4 calipers and rotors. This is the exact same dimensional difference when someone made hats to go on the 86T (rear hub mount) and fitted 32mm wide Wilwood rotors and S4 calipers (i'm working on a kit to get rid of the 86T spindles and hubs for good). Did 928's come out with any M030 designation?

 

I think all the 928 later year rotors are 7.5mm thick. i measured my GTS rotor, the 965T rotor (same) and they are 7.5mm. i would think the S4 rotor is that 7.5thick too. do you have a drawing? i think the only rotor that is 6mm, is the early 928 rotors.

also, the spec on the cayanne rotor is 68.5mm offset. (or thickness rotor rear face to outside of mounting flange.)

if we do the calculation with the mounting ear being 19.25mm, what do we get going from a 60mm rotor total thickness of the early 928 rotors?

a little adjustment is required.

btw, what are you talking about "differences with the heavly blanched rotor"?
we are not using it, its way off as far as thickness, obviously, its just being used for diameter bolt pattern and set screw. also, the set screw on the 928 rotor is not 130mm like the cayanne, its a little futher outward as you can see from the pic

mk

 

ear is 19.25"
offset difference is 8.5mm
so, we want the mounting flange surface mount to be the difference of these two numbers, or 10.75mm

with a 25.4" thick block of alloy, means the thin part thickness would have to be 14.65mm. (I think this was the 15.15mm dim based on a 69mm offset, but its really 68.5mm)

BUT, if you add the 1.5thicker mounting surface as you note, then the 14.65, really becomes 13.15mm

RIGHT????

 

A properly re-surfaced rotor is Blanche machined. I thought you were going off the old rotor. 0.5mm is somewhat trivial. I think Centric may be off in their diagrams. I have a few quality diagrams of Brembo's rotor dims and the Cayenne single setscrew is 130mm PCD, whereas 944/968 is 136mm (m6 x 1.0). even if I machined the Cayenne setscrew dim in the billet hubs, don't know if I'd trust the concentricity after wheel bolt-up on the Early hubs.
That said, I suspect the Later 928 hubs are 157mm O.D. (heven't the rotor specs like you have) and those wouldn't need centering rings with the Cayenne rotors, then again, will the wheel still clear? who knows.

YES to your last question, sorry.
And you're still over 1/2" thick billet....no problem, if it were a worry you could add that thicness to the caliper bolt thru thickness on the caliper side.