pcar928fan

So, now we are going to have to remove the calipers and grind on them and then put them back on and bleed the system? Wow..."no big deal"...yea, if you have a grinder and a brake bleeder... Guess I'm out...damn!

xschop

If you are careful enough (and lazy) you can grind the S calipers without un-bolting the lines. Speaking of lines.... a bump for the front lengths and hard line interface threading? Got lucky, these wilwoods came with adapters to male -3an

hacker-pschorr

Hey guys, once this is all figured out, please update the original post with simple and specific details for those of us interested in a brake upgrade.

mark kibort

no, not at all. yes, you are grinding on the edges of the slider portion. the caliper doesnt need to be removed. you just grind a little space with a 4" wheel and it takes less than a few mins.

no grinder, no bleed, just hand tools, much easier than what I did on the S4 caliper.

pcar928fan

Well, I guess I will just have to see it...I can't imagine trying to hand grind something on a brake caliper, especially insitu.

mark kibort

the grinding is easy. I did a much more critical dimension with the S4 calipers.
with the S calipers, its steel, its not connected to the critical caliper parts, and a grinding wheel or cutting wheel takes off material very quickly and easiliy.

mark kibort

Not that it matters, but the measurment of the S4 rotor is 77.5mm for offset and the thickness of the hub mount is 5.8mm as mentioned. Its so funny, how after 20 pages of this, Im still learning stuff.

the cayanne rotors are tough to gauge for offset, because so much material is gone from the rotor face, so its unlikely that the rotor lost or was turned evenly, side to side. (5.5mm or wear) BUT, if it did, the cayanne rotor, who is only at 26.3mm thickness (and should be 32mm new) would have a 68.5mm offset.

now the 7.5mm vs 5.8mm face thickness throws a little clitch on our calculations. so, the 68.5mm offset , suddently becomes 1.5mm more shallow, compared to the S rotor 60mm offset. So, the real distance instead of the 9mm really used for the modification, its more like 7mm. the 15mm dimension of the part really should be 13mm, right?

Mk

mark kibort

I measured the distance from the disc to the lower ball joint. 16mm, but that is on a well below spec thick cayanne rotor. So, call it 13mm of clearance. thats it, so this is why an S4 or GTS offset wont work.

did some grinding on the pad framer part of the calipers. this part comes right out of the calipers and is used for framing the pads, and mounting of the main piston caliper portion. so, you can remove it out of the calipers very easily. it just slides out .

the interesting thing is that the "Pad framer" part, has a very tight clearance with the rotor, out side and inside. visually, it looks like only about 2mm on the outside and 2-4 mm on the inside. (using the stock rotor) So, this adapter position is critical.

I measured the rotors and got 60.3mm overall thickness. If the spec is correct on the cayanne rotors, then its 68.5mm. using that, plus the addional 1.5mm thickness of themounting hat flange, the adapter spec we made is off by 1.5mm. the 15.15mm dimension needs to be 13.15mm. the total offset difference us 7mm for the "S" rotors and the cayanne rotors. (including the 1.5mm greater thickness mounting surface on the hat of the cayanne).

19.25mm - 7mm = 12.25mm
24.5mm- 12.25mm= 13.15mm

anyone see any issues with this math?

this will be the final dimension for the adapter.

xschop

Haven't got those adapters knocked out yet....

mark kibort

free puts you at the end of the list for priority.

xschop

My new Cayenne rotors showed today. I will be in the shop tomorrow on the 944 spindle/hub mock-up first. The 928 will have to wait a little longer cause I have the hub bearings removed for tolerance verification for the billet hubs. I was jesting, I understand slowly but surely.

mark kibort

You need to verify the total thickness for me. It needs to be 68.5mm as the drawing says, otherwise the adapter Im making will be all wrong! If you understand how the 2 piece S caliper attaches, you will understand. the front part is only 2mm off the surface of the rotor, so very little margin for error for position.

mark kibort

Here are some pics

notice the gap of the slider,pad framer, to the rotor. this structure is how the caliper is held in place it holds the caliper and allows its lateral position to be free, and guides the pads perfectly oriented to the rotor face.

xschop

I went to the garage and busted the box open for ya....how about...

68.6 ........on the digital and analogs

EDIT.....Damn bigass rotors LOL

I'm excited. They're going to clear the knuckles on the Early hub/spindles....bonus

76FJ55

There is always the possibility of using shims to fine tune the position. Since the adaptor is bolted to the back side of both the caliper and spindle it is possible to shim in either direction. If the caliper is too far outboard place the shim between the spindle and addaptor, or if the caliper is too far inboard a shim could be placed between the adaptor and the caliper.