I'm installing my h&r springs this weekend and also ordered a stud kit and spacers to set my stock 18's out a little. Studs are to get rid of the wheelbolts and spacers for aesthetics and the spacers are only there for street use and will never see the track.
I got 7mm for the front and 15mm for the rear. I'm ok with the front sliding over the stud and sandwiching it with the rim, tighten the lugs down and you're done.
I have a problem with the rear. I expected once you go over a certain distance that the studs would then be pressed into the spacer with it being countersunk and screwed to the hub. What I have is ....well.....a spacer. I guess just what I ordered. The aluminum disc has holes for the studs that are huge clearance and you are totaly relying on sandwich torque to not shear them off. What happens if the lugs aren't perfectly torqued?
I've built many cars and pretty savvy in a machine shop and just don't feel comfortable having 15mm of unsupported thread on a rear wheel and don't see how it can safely handle the rotational stress of accelerating and hard braking.
Am I being too critical?

You might want to check on 15mm OEM Porsche spacers. I have 18" Carrera S wheels on my Boxster and needed 17mm spacers to clear. I bought OEM Porsche spacers and these spacers have the studs pressed into the spacers, so the rear wheels on my Boxster are attached by studs and lug nuts, not lug bolts. I'm pretty sure that the OEM 15mm spacers are the same , i.e. with studs and lug nuts. They were a little pricey, about $230 for the pair, but I'm happy with them.

I didn't know porsche offered a spacer that big, I'll check into it tomorrow. For a pressed in spacer that price isn't too bad when 2 15mm spacers are $130, 10 studs are $50 and 10 lug nuts are $80. It just scares me into not using them when I think of the hub slowly turning, then the studs twist and then the wheel rotates.


How does porsche attach the spacer to he hub?

Hello thunderball,

I had the same concern when I purchased what I'm assuming are the identical 7mm and 15mm spacers from H&R this time last year. When I contacted H&R about my concerns they replied that the factory OEM wheel/stud configuration has approx. 10mm of unsupported stud length and that increasing it an additional 15mm is engineered well within what is a conservative margin of safety.

They said this is the preferable set-up to minimize unsprung weight but for spacers greater than 40mm it is necessary to use hub adapters (this type bolts to the hub then utilizes bolts or studs depending on the model).

Just a tip, before you secure the spacers to the factory hubs with the mounting screws (provided), clean up the hub's mating surface and apply a thin coat of anti-seize lubricant on the same. This will eliminate the formation of any corrosion over time which could potentially effect the precision mating. This would also be the ideal time to spray-paint you rotor's hubs with an engine enamel (I used silver) if you are so inclined.

If you are interested in factory OEM type wheel locks for the 7mm and 15mm set-up, please take a look in the Cayman Clubs classified section as I have one set available.

Regards,
Joe

I don't know where you buy your stuff, but I paid under $140 for 2 pressed in stud 15mm spacers, under $20 for 20 screw in studs and under $60 for 20 polished aluminum lugnuts. Bolt a 15mm spacer with pressed in studs to the hub with the oem lug bolts. I converted all my hubs to studs and use steel lugnuts for track and aluminum for street.

__________________
Dan

This thread gives me some concern. I purchased (from Ralph Booth) and installed 15mm spacers on my 19" rear Turbo wheels. The spacers are only held on with the longer wheel bolts also purchased from Ralph. Should I be concerned about the rear wheel setup on my car? Do larger spacers (say greater than 5 or 6 mm) need different wheel fasteners?

The spacer attaches to the hub with the original length lug bolts. The attachment points are dished for the ball washers - remember that I'm using OEM wheels as well, so the lug bolt head fits in the recess between the wheel's through holes. FWIW, the PN for the 17mm spacers is 996 361 617 00 - one vendor I checked has these for about $80/each plus shipping.

I have used plain 15mm spacers on tracked cars with no problems. Also never had a nut nor bolt loosen when properly torqued. This thread seems to be based on premise that bolts/nuts may come loose. In my 9 years of extensive track driving using high quality spacers, studs, and steel nuts is that they do not come loose. YMMV...

I purchased the set from a forum vendor.


Thanx for the oem pn, I think I will order those because in my experience nuts do hold torque better than bolts and I think it's a step up for the car. To have 25mm of unsupported thread on your drive wheels is crazy and it may not be so bad if the holes in the spacer weren't such big clearance. Sorry I don't have my calipers here to measure them.

I was just wondering if anyone has had any issues.

Thanx for the opinions.

I'm surprised you guys think that it's ok to run a 15mm spacer on these cars. Anyway I decided not to and sent the overpriced package back, time for some new wheels.