rdean

Listers, I'm perplexed and need some help. Please see below email that I have sent to Wheel Enhancement Inc (without a reply yet). Any thoughts, advise, comments?

Thanks in advance.
rod911964

I have been directed to your site to clarify a technical point specific to stud and nut engagement on my Porsche 911 C2 RSA.
I have on hand 4 ea 1/4" wheel spacers that I would like to install on my RSA. When I installed the 1st spacer (one for each wheel) I noticed diminished nut to stud thread engagement. Here is what I have been told and I need to know what is acceptable/safe.

1) without the spacers the nut to stud thread engagement is 100% depth of the nut. The stud "tops off" flush with the outside top of the nut with 94 ft/lbs of torque.

2) with the spacers on I get about 6 revolutions of thread engagement, nut to stud

3) I have been told...
3a) a minimum of 3 revolutions is adequate/safe per Porsche specs
3b) 9 revolutions engagement is required
3c) the diameter of the nut thread is the minimum engagement to the stud.

So there is my dilemma. Can you please provide your "expert clarification" of what is acceptable/safe.

newsboy

A quarter inch is 6.35 millimeters. 5mm is the recommended maximum, without changing to longer studs.

Marc Shaw

Get a couple of open-top steel nuts and see how much thread is engaged. I would not drive the car if all the threads of the nut are not securely engaged when fully tightened.

Before I went with larger spacers (and swapped in longer studs), I found I could safely run 1/4" spacers with full thread engagement.

The torque for wheel nuts is 96 ft/lbs.

Marc

cobalt

Unless you have wheel centering spacers you don't have enough support. The wheel centering hub on the rotors is 7 mm and you need that to support and center your wheel. If you use anything more than a 7mm spacer you need to install longer studs and buy wheel centering spacers. AFAIK RUF is the only supplier of these at around $99 each.

BTW at our DE events you would not be allowed to use spacers without steel open ended lug nuts and no more than one rotation of thread can be visible. Correct torque is also 96 ft pounds not 94 and you can go to 100 with steel lugs if you like.

race911

Concurring with above, I run a 1/4" spacer on the left rear of the RSA with the 9" Cup 1's and 275 RA-1's to clear the oil line. And it's MARGINAL. (I converted RSA #1 to longer studs and could run a variety of offsets and spacers.) The car sees such light track duty at private DE days and such, and I'm extra vigilant, but if I were running tech for a club DE I wouldn't let it pass.

race911

Duh, RIGHT rear...........

rdean

Thanks all....
I need to select 1 of 2 options. Either install longer studs (1) or return the spacers (2).
By the way, I am currently using open steel nuts on what I understand are the factory studs with only 50% thread engagement, not good!
rod911964

pete000

I run the 5mm spacers and torque my alloy nuts to 80 lbs. I had a set get twisted removing them when running over 90 lbs.