[s-cars] I'm finally studly... (long)

[steve powers]

(cross-posted to BIRA, S-cars and NW Audi)

Since installing my BIRA Sys 6 brake setup, I wanted to install wheel
studs to make the wheel installation easier. At issue is the additional
3mm of rotor hat thickness which sort of defeats the hub-centric wheels
where you put on the wheel, spin and slip in a bolt - all at once. Studs
seemed like the best way to go, so I began researching the problem.

The urS6/S4s use a pretty hefty lug bolt size (14x1.5mm). Removing one
lug bolt and measuring several times with a 16p nail, hooking the head
on the backside of the hub, I came up with a stud length target of 60mm
overall length. I figured this length should allow for a to-be-sourced
lug nut and still not protrude from the wheels.

Calling a local vendor for H&R lugs I explained how I measured and what
I wanted. They got the lugs and I took them home. They were wrong - too
long by about 20mm! The studs consist of three areas: hub thread, waist,
and lug thread. The length H&R quotes is lug thread. It makes some sense
as you are supposed to thread in the lugs, bottoming them out in the hub
on the waist of the stud. Re-order, this time in H&R's 40mm length.

Meanwhile, I need some nuts. The stock wheels (and my 3 piece HRE
wheels) use a ball seat. The rub is that there just aren't any
aftermarket ball seat lug nuts. I checked with Tire Rack and others,
including searching the web. You can get the standard steel ones, which
I did. (Note: most aftermarket wheels use cone seats and you won't have
this problem - it's just that mine didn't)

I did discover though that Porsche also used 14x1.5mm lugs. They
previously used lug nuts (alloy even!) on all of their cars but recently
went to a funky lug bolt setup with spinning ball seat collar. I went to
the local P-car parts dept. and bought one of the older black anodized
allot lug nuts. It was the right thread pitch and may fit, though I
wouldn't know until I installed the studs.

I got the new studs today. I immediately removed a lug bolt and put in a
stud. It fits! I jacked up the car and installed all the studs using red
loctite and torqued them to 100 lb-ft with a double nut. I put the wheel
back on and tightened a couple of the steel nuts on. I measured to see
if the stud would bottom out on the Porsche lugnut. Nope, it will work.
Yippee!

Because I only had one Porsche nut, I installed the steel nuts. I have
found an aftermarket supplier (www.boothedesign.com) for Porsche lug
nuts in polished stainless. At $7 each, they're cheaper than the local
Porsche dealer, who wanted $10 apiece for the weaker (but lighter) alloy
ones. Boothe Design can also provide matching locks.

Moral of the story: order the 14x1.5mm studs in 40mm length and hope
your aftermarket wheels have cone seats. (you will need ball seat nuts
for the stock wheels)

Steve Powers
95.5 S6 Avant