Vilhuer

'90-91 Exclusive cars are different than '92-95 GTS. I think they used 43mm bolt on spacers while GTS has 38mm slip on type.

the flyin' scotsman

I can confirm the GTS has a 38mm slip on spacer so the studs are quite long.

Installing a thinner component may require a creative solution for the wheel nuts if the wheel hub dimension allows the OEM nuts to bottom out as Chuck suggests.

I do have to temp install a rear wheel on the side I took the spacer off and measure to the fender per the TrackPlus site.

the flyin' scotsman

Further info......the rear wheel installed with stock 38mm spacer sticks out well beyond the wheel well.........the other side with spacer removed the tyre rubs the inner wheel well so Im giving serious thought to shaving the OEM spacers down to 15mm......thoughts?

Vilhuer

See how long threads there are in those long bolts. Its very likely you can't remove 20+ mm of them and still have enough thread for safety.

Dave928S

Just measured mine ... with standard 38 mm spacers the threads project 32.3 mm, and the total thread length on the the bolts is approx 44 mm.

If you reduce the spacers to 15 mm (reduce by 23 mm), you will have 55.3 mm of bolt projecting ... the first 11.3mm plain bolt shank, and 44mm of thread.

With the 15 mm spacer and the bolt cut down to give the standard 32.3 mm projection you'll have 11.3 mm of bolt shank and 21 mm of thread.

A standard Cup 2 wheel has 9.6 mm of plain hole before the tapered seat for the lug nut, with an inside depth of the lug nut threaded hole of 29.30 = total depth from inside wheel face to end of threaded lug nut hole of 38.9 mm. Standard thread projection as already noted is 32.3 mm ... therefore the standard thread engages with the standard lug nut 22.7 mm.

So ... as was calculated before you would have only 21 mm of thread with the cut down spacers and bolts (to 15 mm spacer thickness). To get standard factory engagement with the lug nuts, and avoid them bottoming on the plain section of the bolt shank, you would need to cut down the spacers to a thickness of 16.7 mm (say 17mm not 15 mm), and still leaving 32.3 mm of thread projection from that, 22.7 mm (23 mm for 17 spacer) of which would be threaded.

This assumes any new wheel would have the same 9.6 mm of plain hole from mounting face to bottom of lug nut taper.

the flyin' scotsman

that's excellent Dave.......I'll verify the plain hole dimension of the rims then determine the final spacer dimension.
15-20mm does seem to be the range previously noted above so a calculated 17mm makes sense......cheers

Don Carter

Dave, good point. At 15mm, I have had some of my lugs damaged by the studs poking through the end. If 17mm will still allow the tires not to rub, that may be the best thickness.

Dave928S

Don ... that problem is a slightly different but still part of the big picture to get right.

17 mm will ensure that the lug nut doesn't reach the end of the thread of the bolt.
To get damage by having the stud poke through the end of the lug nut, the projection of the bolt from the spacer would have to be more than the factory 32.3 mm ... for it to push the end out it would be greater than 38.9 mm.

So .. you need to get two things right
1. not have the lug reach the end of the thread and risk no clamp of the wheel, by having too thin a spacer (min 17mm), and ..
2. not have too much thread projecting from the spacer, which will punch out the end of the lug when wound on (factory 32.3 mm ... greater than 38.9 mm will push the top out).

the flyin' scotsman

I sourced spacers through a CDN disti who sells made in Germany H&R products:

the flyin' scotsman

Further to Chucks point the realities of the wheel dimension with a 15mm spacer do require open wheel nuts as the OEM lug nuts bottom out well before the OEM threaded stud is taken up.

The 17mm calculated spacer is a very good starting point but very dependant on the wheel dimensions.

Bertrand Daoust

Hi Malcolm,

Those I'm sure will bring your car to even a higher standard.
If this is possible...

the flyin' scotsman

thx Bertrand.....still pinch myself that I own this very rare car

UncleMaz

Set for sale. $1200. Not a screaming deal, but a fair one... Given rear tire width, may be 11s.

http://ventura.craigslist.org/pts/4469046118.html

Courtshark

If this thread covers most people who have 11" CIIIs on a 928, looks like I might be the only one trying to fit them on an S4 without GTS fenders. My fenders are slightly rolled, but there's room left for more.

The 295/35/18 on the wheel now is damn tight. The 11s, without any spacers, also come within a finger-width of the rear suspension, but do not rub either side. The previous owner had tried to fit these to a 944 and gouged the outer sidewalls. I took a short spin around my neighborhood and did not hear or feel any rubbing. Of course, the sidewall gouges might be why I didn't hear any rubbing from the outside of the tire!

Nonetheless, I think 295/30/18 might be a better tire size for this application (S4 with rolled fenders). Fortunately this size is available in a lot of very nice tires, including the R888s I'm currently running on the 10s. Thoughts welcome on going with 30 profile tires, though...

And yes, AO, they look bad *** in black!