5x5 ss wheels shift on 1971 rotors

[luvbowties]

We put a set of 1988-1992 Chevy pickup SS wheels on 1971 rotors using the 1/2" fine thread studs and lugnuts--the lugnuts with both internal and external threads(external to hold on the center caps). Hit a light to medium pothole, and the victim wheel will be knocked 'off-center' and "cam along" instead of rolling true. Always on a front wheel--never a rear.

Can remove & replace carefully, torque them to 80 ft-lbs, run true until another pothole, and it will do it again.

Any ideas to correct this problem?
Thanks,
luvbowties

[Captainfab]

If I'm not mistaken, the '88+ trucks have 14mm wheel studs. On the '71 rotors are could the lugnuts be bottoming out on the rotors before the wheels are actually tight? If so, you could either remove the studs and countersink the holes enough to allow the lugnuts a little clearance. That or shange to 14mm wheel studs. I assume the center hole of the wheels are larger than the hub register of the rotors? If so maybe a machined ring to press onto the rotor hub to hold the wheel hubcentric.

[jweb]

Most wheel & tire shops have hub centering rings. They are plastic and take up the gap between your hub and wheel. Probably not the right way to fix your problem but it should work. They are used often with aftermarket wheels.

[slepysal]

another option would be to use an "ET" style lug nut . It has a small shank and should aid in giving a lug centric fitment

[luvbowties]

Thx, Captain, for the quick response. Seems I recall a difference of 0.079 inches between the hub od and the wheel id. I tend to agree with your belief that the lugs bottom out on the rotor before wheels are really tight. We considered 'shaving' a bit off the taper of the lug nuts, making the ends fatter so as to hit the wheel before the rotor. This, rather than machining a ring so critically thin--esp. since we don't have a lathe. I'd really love to have this ring idea PLUS either tapered rotor holes or shaved lug-tapers.

I'm beginning to agree with you about tapering the stud holes. This may be simpler and more doable with the simpler tools we have access to. We already tried thin spacers(1/4 inch, iirc) with larger holes directly behind the wheel's lug holes. They slipped again with this spacer setup, and I still wonder why?
As always, thanks again for your expert analysis and ideas.
Sam

[AJNapierski]

Or put the steelies back on it

[wbc409]

There are different styles of standard lug nuts also. Some have a larger tapered seat for aluminum wheels. Standard taper for a steel wheel doesn't have the large seat

[wbc409]

If your favorite parts store still has a catalog you can see what different nuts are available.

[jonzcustomshop]

in high school I put 87-88 iroc wheels on my 70 Camaro, I used the nuts that came with the wheels, they torqued down just fine. a couple weeks later my left front wheel left the car that "mud" I had seen flying off the left front on a rh corner wasn't mud, it was all the lugnuts!!

anyway the modern Camaro had switched to metric, which might be the problem you are having as well since it covers the same year range. at the time that I lost the left wheel my rear lugs were still tight, but the right front were starting to loosen up too.

[luvbowties]

Originally Posted by AJNapierski

Or put the steelies back on it

You are really tempting me. But I need 7-inch wide wheels and my steelies(rallies) are 8 inches wide--8-inch rears are difficult to change if you have a flat.
s

[slepysal]

try the ET style lug nuts