Rear Wheel Studs for 1968 Riviera

I also posted this in the Got Gears? section, but thought someone might have had this problem specifically with second gen Rivs. I figure anyone who has put aluminum wheels on a 68 Riv will have had this problem if the wheels use the conical seat lug nuts.

I bought a set of aluminum wheels, 15X8, and the wheel studs on the rear axles are too short, only giving me about a half inch of lug engagement. I figured no problem, just get longer studs and put them in. Wrong.

Went to NAPA, checked Dorman, and hell, they only show about a half dozen listings for wheel studs with a .621 knurl, and they're all too short too. Anybody got an alternative, like a different source or company that manufactures wheel studs? I checked ARP, no .621 studs. Any possibility of forcing a .625 knurl stud into the holes in the axle flange? I'd hate to have to redrill the axles and also the brake drums to accept a larger knurl, but if that's what it takes, I guess I'll have to. Appreciate any help.

Thanks.

 

Can't help with a source for longer studs but if you in fact have a full 1/2" of contact on each stud, the wheel would break apart before the threads would ever pull on the nuts or studs.

I am not an engineer and don't honestly know how much is considered safe for a wheel nut so have to add this disclaimer. This is only food for thought that you can investigate more.

A a 1/2" UNF fine thread stud has tremendous thread shear strength. Over 10,000lbs of force which is a conservative number. I'd have to think thats way more than the aluminum wheel could withstand given the small contact surface area of the nut. Then multply that x 5 lug nuts.

 

Jim, see your other thread. You simply need the correct lug nuts to run the aluminum rims with your original studs.

Devon

 

Devon, thanks, I saw the reply from Larry. Problem is, the wheels I've got have a conical seat for the lug nuts (45 degree cone, I think), so the type Larry showed in the picture won't work on these wheels. That type is what I've used on Centerline wheels in the past.

But I'd pretty much agree, if I've got 1/2" of lug engagement (which I just estimated by eyeball, I'll check) I'm not really worried about shucking off a wheel. But if and when I put slicks on it, then a diligent tech guy will be looking for 1/2" of stud protruding from the lug, and that I sure can't do with the stock studs. I don't know why I thought finding .621 knurl studs would be easy, not much else on this project has been!

 

Bummer!

Regarding sufficient thread engagement, you should have a minimum of two full threads of the lug exposed after the lug nut is fully tightened. Less than that is considerend substandard as far as fasteners go.

Devon

 

Jason,

It'll take a regular chrome acorn (or even some old ugly regular lug nuts) that has the conical end, but the wheel is just thicker than the stock steel wheels. Result is that the stud only extends a 1/2" into the lug nut (or thereabouts). I can thread on a regular lug nut and it lacks a turn or two of the stud coming out even with the top of the nut. I'll try to get a picture tonight and see if I can show the problem. Thanks.

 

I took a couple of pictures of the lugs and how they fit when the wheel is mounted up. The only solution I see is longer studs, either with the correct knurled diameter and shoulder or I'm going to have to modify the axle flange and brake drum to fit the studs that are available. I checked Jegs and Summit, no luck on a .621 knurled diameter there (some don't have specifications, so I'm not sure how you're supposed to know for sure what you're buying fits what you have).

On pic shows the wheel with two lug nuts lying on it, one the long capped nut that came with the wheels, one the old lug nut for the stock steel wheels. They both have the 45 degree taper that fits down into the taper in the wheel.

The other picture shows the wheel installed with two new lug nuts and the old lug nut. Probably not a real good picture, but the threads end just a little inside the top of the old lug nut.

 

Jim, with the amount of thread engagement seen in the second photo, I say definitely get some longer studs. I don't like raining on anyone's parade, but it's got to be done. I'm sorry I can't steer you to the right place for the longer studs.

Devon

 

Devon, I agree 100%, and I can look at it til the cows come home (old Missouri saying) and it won't change itself. I'm sort of convinced that they don't make .621 knurl studs in a length that I can use. I'm going to pull an axle, remove a stud, and verify the diameter. If it's actually .62, I'll see if I can get something slightly larger with the correct length shoulder and grind down the knurl a few thou. Probably have to grind down the shoulder some also, to clear the stud holes in the drum. Then I'll find some outfit selling studs in .621 diameter and 2" length for a dollar a dozen!! Anyway, thanks man.

 

Jim, you're looking at it from the smart side..keep up posted!

Devon

 

I put longer studs in the rear of my 69 Riv with no problems. No shearing or any of that stuff (can't figure out Jason's post). Work great. I'll try to figure out what studs I put on and where I got them. I am thinking NAPA. I'll let you know.

 

The Riv would need rear studs with a .621 knurl diameter, 5/16 shoulder, 1/2-20 thread in the desired length. Measure yours and then ass a half inch. Then see if you can find anything with these dimensions.

 

Call Tom Telesco. He cross ref'd it for me and was dead on. 203-324-6045. Tell him Yardlley told you to call. I was just talking with him last night. He won't mind.

I'll still look and see if I can find whivh studs I bought.

 

Thanks Yards, I just got off the phone with Tom about an hour ago, he had a long list of possible wheel studs that would work depending on the distance from the cone seat in the wheel to the outside of the drum. He also said that it's possible to pull a .625 knurl into the axle flange, which opens up a whole range of possibilities because there are about a million studs with that dimension. Appreciate your help here! Also, hope you get the problems ironed out on your motor, it's got to be frustrating when the thing lays down for no apparent reason and none of the changes make it respond.

 

Sure thing, Jim. Glad to help.

I should have the engine fixed and dyno'd by Thursday.

 

Just wanted to post a follow up, I went to an auto parts store of the old time variety (they've actually heard of '68 Rivieras and didn't ask what motor it has in it when I asked about wheel studs) and we ordered studs for a '67 Riv front with drums. They're a .625 knurl, 2 inches long. The punched out the old studs and pressed in the new studs for a total of $29 and change, $10 bucks an axle to remove and replace plus $9 something for the studs.

Only problem I had was some of the studs were a little angled, so the drum wouldn't go on easily over the studs. I tried using a couple of washers and a large nut to act as a standoff, then driving a lug on with an impact wrench. Didn't help much. So then I took the lug nut and a BFH and whailed away at the studs a couple of times. Drum went right on after that. Installed the axles, drums, and wheels, ran all the lug nuts down good and tight, that seemed to pull the studs all into alignment, now everything seems to fit fine.

I've got about half an inch of stud sticking through the lug nuts now, should be good to go. Gotta do the same routine on the rotors and hubs on the front now, but they're off of a '71 - 76 Riviera or something, I'm using the Scarebird brackets and late model stuff for the disk brake conversion on the front.

Oh, I've got questions on what size tire I can fit on the rear of my '68, posted in The Hides section.

Thanks for the help and advice from all the people who responded to this thread!!

 

Your welcome Jim.

Tom T.