HELP!!! ARP Wheel Stud exposed knurl

[Chadman27]

Hi everyone,

I am a long time forum viewer (since 2004) but rarely post. Well, actually my last post was in 2008 for a steering box question, but I have since forgot my username password (lack of posting ) so I recreated a similarly named account not so long ago. I have found myself in a jam on my project, hence rekindling the posting flame! I could really use some of your guys experience and knowledge, so here goes...

I recently ordered my front brakes for my 81 T/A project, and had DSE/Baer machine the brake rotors for a 1/2-20 wheel stud. The studs are ARP 1/2-20 cadium plated 3 inch. The knurl of the stud sits flush on the rotor and are perfect, but this is not where the problem lies.

About a year ago I received my DSE built Quadralink GM 12 Bolt rear with the 1/2-20 3 inch wheel studs. Because DSE uses Moser rears and components, the studs are black oxide coated studs PN 8010 (verified with Moser over the phone) seen here:

http://www.moserengineering.com/othe...long-ford.html

I have recently ordered my CCW Classics, and was really against cutting studs so I could run a closed stud. I figured I'd rather have the open lug where engagement length could be verified easier for track days. That being said I wanted the rear studs to match the fronts, so I order ARP PN 100-7703 .625 inch knurl studs, seen here:

http://www.jegs.com/i/ARP/070/100-7703/10002/-1

Well I popped a stud out and pulled the new ARP studs through, to find that the knurl sits proud roughly 1/32 ~ 1/16 of an inch. I did not have my calipers available where I work on the car, so I could not take an exact measurement.

Moser stud:



ARP stud:



Side by side comparison:



When placing the Baer Pro+ rear rotor on, the chamfer depth bottoms out on the exposed knurl. Has anyone ran into this issue... how did you resolve it? I feel that the when torquing the lugs when mounting the rims, backing the bearing/shoulder off the backside of the axle flange is obviously unideal, and potentially dangerous in regards to snapping a stud - am I right to think this, or would the limit relief of the stud shoulder not be an issue. My thoughts and options are listed as follow...

1) Because the Pro+ center is aluminum, I could purchas, lets say a .750 inch countersink bit and machine the per-existing chamfers of the rotor to attain clearance... My only reservation is that I know Baer would never approve of such a procedure, being a liability, and I could potentially compromise the bearing strength of the cross section. Has anyone done this successfully? Recommendations? Because the aluminum is soft, I believe I could get away with doing this with even a wood countersink bit... recommendations?

2) Source some type of washer to recess the stud back the required length... realistically this would be very difficult, as I dont beleive any ASTM/ASME spec would ever point to such a washer with such a thin ID to OD width.

3) Keep the wheel studs as are, protrusion and all, but source a thin wheel spacer that I can machine the chamfer (if not large enough on the spacer as delivered). This would eliminate cross section reduction of the rotor which will see load under hard breaking... I just need to make sure I do not rub the wheel wells with the new offset. As it stands, the rims are 18x12 w 5.5 BS on a 9 inch (4.5 inch per side) narrowed rear. Being that the Firebird wheel wells have a little more room than its Camaro counterpart and I have also Eastwood fender lip rolled the wheel lip edge... I may be lucky enough to get away with this. Any advice on wheel spacer with large chamfered ID's... I know there are probably a million companies to choose from.

4) Knock the ARP studs out, quit being a baby, and cut the original Moser studs to necessary length to run closed lugs... Cut the front ARP studs to match. I really don't want to do this, but will leave it as a final (and safe) option.

If you have made it this far, thanks for giving my post a look. I hope you can share any advice or insight. I've been working on my Trans Am for about a year an half now... its been my baby since I was 15! I've been wanting to post a build thread... but never seem to find the time to do so.... the one time I tried my post took about an hour to write... when I posted there was an error and all was lost! Maybe I'll get around to it again here soon.

Thanks,

-Chad

[astroracer]

Clean up the moser studs and spray on some Eastwood cad paint?
Make a thin spacer from sheetmetal? You can do this yourself. It doesn't have to be perfect as it won't register the hat, just space it out a bit.
Chamfer the back of the hat. This will not create any strength issues at all. Nothing to worry about. (The route I would take)
Do some digging and find a .625 knurl in the underhead length you need.
Just some suggestions
Mark

[nvmyss]

Option 1
This had to be done on ATS studded spindles with some rotors.
I've done this twice and I know others have.

[Chadman27]

Thanks for the input guys. I realized today that Option 3 would not work with shim packs I have for Baer's for the required length I would need to shim out the caliper to center... I suppose fabbing some washer to thickness and OD is more trouble than its worth.

I think I'm gonna go with Option 1 tonight. Thanks for input this has been done before, I feel a little better about tooling on brand new set of rotors.

[Chadman27]

Double post... my bad.

[Chadman27]

Well I know sometimes its nice to see the follow up from others advice, especially for others doing research who may be interested in doing the same thing. That being said, here are the results. I used a 3/4 inch counter sink bit. I tried a 5/8 inch drill bit, but since I don't have a press, as soon as it started coming out sloppy I stopped. The countersink cleaned it all up, proved a lot easier to use as well as it centered itself.

Backside of Hat (hopefully there is adequate material left, I think I should be OK )



Rims mounted:



Mounting finally allowed me to test fit of Quadra-link w/ rims on:



Thanks for the help again guys.

[astroracer]

NIce job. Looks good for a hand job.
I see you are building a Bird. Need some pics and details. I have a '73 sitting on the back burner til I get the van done.
Start a build thread and get this dude rolling!
Mark

[LUV2XLR8]

what size are those meats on the back?? is that a stock rear suspension?

[Chadman27]

NIce job. Looks good for a hand job.
I see you are building a Bird. Need some pics and details. I have a '73 sitting on the back burner til I get the van done.
Start a build thread and get this dude rolling!
Mark

Well I guess everyone can appreciate a good handjob ;) haha, sorry had too!

And yes, I've been wanting to do the build thread for a while... I think I mentioned above that I wrote one which took about an hour then it wouldn't post... I was a little discouraged to say the least. I'll start one before the weekend is up when I get some free time. Its always nice to get feedback on what your doing and where you're going wrong before its too late!

To answer the other question no, 18x12 w. 335s. Rear end is built 12 bolt, 4.11 gears, 33 spline axles with DSE Quadralink. Rear is mini-tubbed. Been doing all the work myself in my dad's garage for about 2 years (in October).

[chevelletiger]

If it was me,i would turn down the knurl that stuck out to much on a lathe if you have one or a local shop.phil

[LUV2XLR8]

looks great... keep up the good work!