Still trying to find out a cheap way to give 13" rotors to the '84's
01-15-2011, 02:09 PM
#256
Man of many SIGs
Rennlist Member
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xschop- Devek did already make an adapter for S4-to-S, and I have it on my car- an 85 with F40 calipers (same size/mount as S4). There is a thread about the conversion in the archives somewhere. I think its called "85 big brake conversion"...
Devek is not in business anymore, but he still owns the design I have here, and I won't make his parts for someone else. Doesn't mean you can't design and make your own, though, its really very simple. His design does require a hat specifically made for that offset, and a rotor that is more $ than most will spend.
So, its been done, but its not the inexpensive way that is the subject of this thread, so I will not hijack anymore....
Devek is not in business anymore, but he still owns the design I have here, and I won't make his parts for someone else. Doesn't mean you can't design and make your own, though, its really very simple. His design does require a hat specifically made for that offset, and a rotor that is more $ than most will spend.
So, its been done, but its not the inexpensive way that is the subject of this thread, so I will not hijack anymore....
https://rennlist.com/forums/928-foru...ake+conversion
01-15-2011, 04:43 PM
#259
7mm spacer is where it's at then. The 74-77 mm rotor offsets can fit without B-joint interference. This is a common hubcentric spacer and the billet ones run about $50/pr, but the perimeters would need to be lathed to fit inside the rotor and the 136mm PCD holes for the set screws drilled....no biggie....
http://cgi.ebay.com/ebaymotors/PAIR-...Q5fAccessories
http://cgi.ebay.com/ebaymotors/PAIR-...Q5fAccessories
01-16-2011, 12:11 PM
#260
Hey svp928, thanks for the link to......"85 big brake conversion"
Looks like someone did take the time to rotate an S4 caliper down. Was that a 2-piece axial/radial welded adapter bracket?
Also the wording was kind of difficult to understand. What was the entire rotor/hat heigth on that custom 2-piece?
I have a set of S4 calipers and brand new 304x32x77 rotor coming from another member to build a kit to put them on the 944 NA spindles with 76 and the 944 Turbo 94mm ears. He said the S4 radial bolts are 130mm C2C which will clear the 94mm ears. I will see what I can come up with for an adapter for these 104mm ears. The other BBK kit that I'm working on for the 928S will have 298x28mmx75 rotors and mount the common axial Porsche Brembo's. I think any radial caliper will have to be rotated for bolt clearance.
Looks like someone did take the time to rotate an S4 caliper down. Was that a 2-piece axial/radial welded adapter bracket?
Also the wording was kind of difficult to understand. What was the entire rotor/hat heigth on that custom 2-piece?
I have a set of S4 calipers and brand new 304x32x77 rotor coming from another member to build a kit to put them on the 944 NA spindles with 76 and the 944 Turbo 94mm ears. He said the S4 radial bolts are 130mm C2C which will clear the 94mm ears. I will see what I can come up with for an adapter for these 104mm ears. The other BBK kit that I'm working on for the 928S will have 298x28mmx75 rotors and mount the common axial Porsche Brembo's. I think any radial caliper will have to be rotated for bolt clearance.
01-16-2011, 12:37 PM
#261
When you try to make an adaptor that will mount to the "S" spindle your run into a problem with mounting the S4 caliper. It is because the one of the adaptor mounting bolts is blocks the S4 caliper bolt as it comes downward to sdrew into the adaptor. The two differring mounting stratagies the "S" from the side and the S4 from the top is the issue.
The problem is that the holes for the two sets of bolts almost overlap, so the holes in the adaptor are right at the edge. This means that a hole could potentially open up. I have tested them to my satisfaction, but I would never sell them to anyone else without a watertight disclaimer.
01-16-2011, 12:45 PM
#262
Edit.....Sorry, wasn't knocking your adapter, the meat around your radial bolt threading shouldn't budge. As a precation you should consider milling a new adapter to leave at least 3/16" billet around the threading and grinding some more on the ears, they are really stout.
What size are the radial bolts tapped?
What size are the radial bolts tapped?
Last edited by xschop; 01-16-2011 at 01:19 PM.
01-16-2011, 02:29 PM
#263
They've done more than a dozen track days with no sign of movement.
All the bolts are 12mm. It wouldn't really be worthwhile to take more metal off the ears as the original bolt holes would mean that much of the extra metal on the adaptor would be taken out when those holes were re-drilled.
One possible way to improve it would be to weld or braze the adaptors on.
All the bolts are 12mm. It wouldn't really be worthwhile to take more metal off the ears as the original bolt holes would mean that much of the extra metal on the adaptor would be taken out when those holes were re-drilled.
One possible way to improve it would be to weld or braze the adaptors on.
01-16-2011, 03:06 PM
#265
S4 calps are radially mounted. S calps are axially mounted. The Radial mounted Dynapro's will allow for a non-tilted adapter to fit a 304mm dia, rotor. The adapter would be ALOT easier.
01-16-2011, 03:19 PM
#266
Nordschleife Master
So this is the adapter you would use to mount S4 type calipers on an S spindle vs. just an adapter to move the plain old S calipers further out to accommodate a larger rotor. Gotcha. That is not quite what we want to do here...we are looking to make this as cheap as possible by just keeping the same calipers and adding more rotor and a caliper spacer...
01-16-2011, 04:17 PM
#267
No matter how you slice the bread, you'l find that the 330mm Cayenne rotor will need centering rings with the offset adapters. Unless a 330 x 32 x 60 rotor can be sourced with 136mm setscrew PCDs and/or 155mm hub interface.... This will not be an inexpensive swap.
01-16-2011, 06:09 PM
#268
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xschop- the adapter is one- piece 4130, no welding. I will see if I can get the rotor/hat height for you, but it is different than anything off-the-shelf. I have made these hats for a standard S4, and the S4 is definitely taller overall, which is why they don't work on earlier cars.
01-16-2011, 07:48 PM
#270
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xschop, if you are talking to me, they do NOT fit under 16's at all- I am not certain a 13" rotor would fit in 16" even with the S caliper- but I haven't tried it, so can't say for sure. I had to space out my front wheels about 13mm to clear the side of the caliper. The OD may clear a 16" one-piece wheel, but the bolt ring on the 17" 3-pc wheel is close to hitting.