69427

Was installing my C5Z wheels for a track weekend and had a problem getting one of the lug nuts torqued (torque wrench kept turning) on the front 17" wheel. I took the wheel off to check if the stud had stripped or yielded, but it looked okay, along with the lug nut threads. What I did see was that the wheel cup (where the lug nut nests in) had "cratered", with a slight lip where material had raised. The other four cups looked perfectly normal (torque at the time was 94#). Do I have a wheel quality/safety issue, or is this an occasional happening with aluminum wheels? I just hadn't run into this issue before on my other aluminum wheels.

Thanks for any helpful information.

froggy47

What kind of lug nuts? Some had a chrome "cover" over the steel nut. They are not appropriate for track. Buy some new open end nuts and try again.

Do not go on track if you can't torque a lug nut.

Pictures help.

JLZ06TR

Could it be that the wheel stud is spinning? take the wheel off and torque an open ended lugnut against the brake disc, and see if you can achieve the torque spec or if the wheel stud is spinning. Put a washer between the nut and disc if you dont want to score the disk.

69427

Using stock Chevy lug nuts, no cover, with open end. Picture to follow if it will focus clearly.

froggy47

Try different lug nuts on that one stud. See if any will tighten. Lug nuts do wear out, usually before the stud.

How old are the nuts, studs?

Clean the nut and the stud with brake cleaner. Try again dry & see if it feels loose.

69427

I grabbed a magic marker and drew a radial line (intersecting the spindle) on the end of the stud, and then installed a different aluminum wheel (an old BBS look alike ARE wheel) on the hub. Torqued the lug nuts to 94# (that's the torque spec they check for at one of the groups I do track days with), and everything tightened fine. No noticeable rotation of the lug stud was evident. To ARE's credit, this wheel had steel cup inserts where the lug nut tightens/turns against the wheel. The Z06 wheels are just beveled aluminum where the lug nuts tighten into.

Next step is to find a magnifying glass and look at the ends of the lug nuts to see if there is a difference on one of them.

froggy47

The only time I ever had that happen was the nut threads stripped out & it was rather obvious.

Wheels without steel inserts will have the "seat" get deformed by repeated tightening of steel nuts onto the somewhat softer metal. I have had galling & since use anti seize to prevent.

Still even if the seat is deformed you should still be able to tighten a wheel on, it's a puzzle.

69427

I took a close look at the lugnuts that came with the (used) wheels, and compared them to another couple of lugnuts I had left over from a previous car ('87 Monte Carlo SS). The present lugnuts have a maximum diameter on the tapered part of about .820". The Monte Carlo lugs (that look like my C4 car stock lugnuts except for the shine) has a diameter of about .910". The Monte Carlo lugnuts fit the C5 wheel bevels very nicely. I don't know what the lugnuts I was using were originally off of, but apparently Chevrolet/GM didn't commonize the lugnut bevel size over the years. Additionally, the lugnuts had a threaded area above the bevel (for phony lug nut attachment I assume), and I believe the threads were the cause of the aluminum displacement.
I'll scrounge up a set of replacement lugnuts, and I should be ready to use the C5 wheels again (although too late for this weekend's track days that I cancelled two days ago).

Not a great picture, but on the stud hole bevel/seat you can see a shiny part where the material was raised up in a crater wall fashion. The other four seats look somewhat normal.

froggy47

I see it, but still, I cannot think that the difference between that seat & the others would be the reason for a nut to not be able to meet a torque spec.

Torque is torque unless threads are stripping out.

Keep us posted.



Never heard of wheels being sold with lugnuts, that's a new one to me.

69427

[QUOTE=froggy47;1590472901]I see it, but still, I cannot think that the difference between that seat & the others would be the reason for a nut to not be able to meet a torque spec.

Torque is torque unless threads are stripping out.

Keep us posted.



Never heard of wheels being sold with lugnuts, that's a new one to me.[/QUOTE]

They were ten year old Z06 wheels at the time, and the seller threw in the lugnuts he was using.

froggy47

[QUOTE=69427;1590474548]I have 4 sets of those, I get new lug nuts every year to 2 years. They do wear if you are swapping wheels a lot. One of the vendors has new ti nuts for about $6 each, I'm thinking of trying those just for fun.

With that wear showing on the seat, I would use anti sieze IIWM and back the tq to 90.



I think your nuts are worn & it's just hard to tell. Buy new ones & try them