greg928GTS

Does anyone know for sure how long the rear wheel studs are on my 93 GTS?

I wish it wasn't 80 miles away from me sitting in the parking lot of my mechanic's place, or I'd go measure the studs myself.

Jim bailey - 928 International

studs the standard wheel stud is 50 mm , the rear widetrack 84-86 they added a slip on 21 mm spacerwith the longer 72 mm studs the GTS they use slip on 38 mm rear spacers so the studs "should be" about 88 mm or so !

Paul Dortkamp

I thought I would add this table to the knowledge pool as it took a while to put this together.

Standard Diameter 14.70mm
Standard Strength 10.9

Length Part Number
40mm 901 341 671 01
45mm 904 341 671 00
45mm 993 331 671 01
50mm 928 341 671 01 Standard 928
50mm 928 341 671 02 Standard 928
52mm 901 331 671 00
65mm 911 331 671 00
72mm 901 331 671 01 For S rear with 21mm spacers
80mm unknown
88mm 911 331 671 03 mm to be confirmed, For GTS rear with 35mm spacer
100mm unknown

Unknown mm 911 331 671 03
Unknown mm 901 341 671 05 For 89GT 17mm spacer

I would like to know if there are any other factory lengths, particularly around 55mm.

Reason being my P club, has a local rule that the studs have to be equal to or greater than the outside of the lug not. My rear is 1mm short and the front is 3mm short. This is in face of that the engineering rule that the enagagemet of a thread should be equal to the diameter of the bolt. I was almost rejected at scrutineering yesterday because of this.

I will update the list if I receive info from later models wheel studs

Rob Edwards

A little followup and a question:

The above post is right about the GTS rear studs, they're 88mm long. But the spacer is 38 mm, not 35. Subtracting the hub and brake disc thickness, there's 64.4 mm of stud sticking out, and appropriately enough, with the 38mm spacer on, there's about 26mm of stud on which to mount a wheel.










Now- the question: I'm looking at some C2S lobster claws (19 x 11 ET51 rears (with 295's on them). Chuck's new Cup 4 11" ET62's will be slightly too far out with the stock spacer, so obviously an ET51 is way out there. So to bring the wheel in, oh, 16 mm would require going from a 38mm spacer to 22 or so. No one makes a 22 mm spacer, but Vertex does make a 7 mm slip on + a 15 mm bolt on (I have the 15's on the GT right now). This would put the wheel in the right place, close to the fender lip.

HOWEVER- Now these long GTS studs would protrude out protrude 26 + 16 = 42mm past the surface of the spacers. If you've used bolt on spacers you know they bolt onto the hub studs with open nuts and the extra stud protrudes into recesses machined in the wheel face.

SO- Anyone got any clue how deep the wheel recesses are on a set of lobster claws? I'd hate to commit and find that the wheels won't sit down on the face of the spacers.....


For giggles I pulled the rear off the GT- If the S4/GT studs are 50 mm long, there is approximately 30 mm exposed beyond the face of the rotor. This, inferred from the studs protruding ~15 mm above a 15 mm spacer:






Boy, if the back of a lobster wheel is anything like a Cup 1 wheel, I've got nothing to worry about - the recess is 70 mm deep:

Barely sticking into the recess:

dr bob

Rob--

Ihave a pair of the 7mm slip-ons on the car now. Let me know if you want to try them for your fit-up.

worf928

In your last picture: are you using a cam setup template as a straight edge? Rhetorical question that. Better: is it the template for S3 motors? Or S4+? 9226? Or 9248?

And, Dude, put some shoes on.

Chuck Z

Great post Rob! Cleared up for me the ambiguity around how big the GTS spacer is w/o having to pull mine off.

Depending on how deep the holes are for the lug nuts are on the lobster claws you may be able to get a bolt on or slide on spacer and stack the lug nuts? Put a shorter steel lug nut on first and then put the traditional aluminum lug nut over top of it? I was considering this option (still might) b/c the holes for the lug nuts on the SE Cup 4s are so deep.

BTW, H&R probably makes the size spacer you're looking for in either a slide on or bolt on. Here is an auction for a 23mm bolt on:

http://cgi.ebay.com/ebaymotors/H-R-2...Q5fAccessories

I am sold on H&R spacers and have used them on our Cayenne GTS and currently have them on a couple AMG cars. Great products!

Rob Edwards

Bob-

I appreciate the offer, may take you up on that. Mostly I need to get up the courage to commit to 19" wheels- 19" rubber is frickin' expensive.


Dave- Sorry, it was the first straightedge that came to mind. I have both the 9226 and 9248 cam tools. 9226 comes with the pair of cam timing templates, the threaded plug hole rods, and hold-down blocks that fit only S3 heads. As I'm sure you know, 9248 is the pair of cam hold-down blocks for 87+ S4's. I ASSume the timing templates are for S3 motors since they come with the 9226 set, but honestly I haven't had to set up any cams on either an S3 or an S4 yet. Yell if you need 'em (or want to clarify their application) and I'll ship 'em over.

RE: the bare feet, if it makes you feel any better, winter came last night- it's raining here. There are about 3 'severe weather' alerts on weather.com

dr bob

Yep, it's down into the mid-60's in the garage right now. Pull out the parkas and overshoes!

Seriously, it was a bit chilly out there in bare feet this morning. It's raining gently, not hard enough yet to cause any slides up here. Forecast is for more later in the week, hopefully it won't be hard enough to start any mud/ash flows up on the burned-out hills north of us.

Rob Edwards

Chuck-

Hadn't thought about that- I have some open steel lugnuts that I could just 'cap' with the black anodized nuts if the studs were too long.

Chuck Z

If the black anodized nuts stick out too far on top of the steel nuts you could always cut the bottom of the anodized nut off provided there are threads left in the top piece?

I had to make caps for some steel lug nuts on a set I-Forged wheels I have b/c the anodized nut stuck out too far above the face of the wheel. Capped them and painted them with SEM trim paint and the look great!

Did you search for the H&R spacers? You have options there too. Good luck.

worf928

Yup. Except that the templates don't seem to come (anymore) with the 9248 hold-down blocks. I've been trying to figure out if they do or don't. I have the full set of 9226 stuff and the 9248 hold-down blocks. But, no S4 templates.

We got 3" inches of snow this weekend.

It's not the cold though. Drop something heavy and your toesies are going to be sorry.

On topic: Is it just me, or do the GTS lug nuts appear to have an extra 5mm of depth to them? Thus, perhaps, stud length has a bigger window of margin.

Rob Edwards

Dave-

Dunno, my car only has the open steel lug nuts. PET shows same part # for 87-91 and up thru '93 (999 182 003 36) but who knows whether that's accurate. I guess in '94-'95 they didn't use lug nuts?

worf928

Naw. My '94 has the black anodized closed-end lug nuts. I swear they are just longer.

(But, I don't actually know if they are 928 nuts - as opposed to 911 or something - cause my '94 doesn't have factory-length studs and has no spacers. (PO's doing))

Chuck Z

Tonight I did some measuring to figure out what type and thickness of the spacer I'm going to need.

From the mounting surface of the rotor to the end of the wheel stud is ~70mm (I don't have a mic so these will all be ~mm). With a 38mm stock spacer that leaves 32mm of exposed thread on the end of the stud.

The recessed area on the SE Cup 4 is ~36mm and the thickness of the wheel at the mounting holes is ~10mm thick. Therefore, I cannot use a bolt on spacer b/c if the spacer is 28mm or 30mm thick, I will be left with a stud that is 42-40mm long and that is too long to fit in the recessed area of the wheel.

I am going have to use a 28mm or 30mm slide on spacer which will leave the same 42-40mm long wheel stud. [edit] there is no such thing as a 28 or 30mm slide on spacer!!!!!! My original math says that the SE Cup 4 setup will sit 5mm further outward than my 3.6 reps so I ordered a set of 32mm DRM spacers which will give me 6mm or 1mm more than I need. .....now it's clear as mud right! Damn, I'm confusing myself.....

Less the ~10mm thickness of the wheel that leaves 32-30mm of wheel stud to screw down the lug nut. Well, an anodized lug nut will only cover ~28mm of stud threads leaving a gap of ~4-2mm. Using a steel lug nut which is ~20mm deep, I would have ~12-10mm to screw down a modified anodized/polished lug nut.

Make sense? Clear as mud right.....