Well got my studs and nuts fixed, for now.

Short story is stripped a replacement NAPA stud, and could not get it off. Took car to buddies house with air tools to try an impact wrench.

Well we stripped it totally. Took a couple of hours to get it off, finally used an air chisel, hand chisels, beer, and air chisel again and it came off. Then found stock stud and stock nut totally stripped. We snapped that one off with a breaker bar, thankfully.

Pressed them out with a big 'ol C clamp, and pulled in the new one's with the impact wrench (set very low), a washer and big 'ol nut as a spacer.

I've never seen studs and lug nuts as stripped as these.

I'm positive the NAPA stud was never over torqued. Can't be sure about the orginal GM. I use a torque wrench on my lugs. 100 ft/lbs, star pattern with a least 3 steps to full torque.

One good peice of advice, the lug nuts I got from NAPA were chrome plated. This plating was also on the inside threaded area, and contributed to the problem. Stupid I didn't notice. However the stock stud / nut had the same exact problem and of course was never chromed. Also the NAPA nut taper was short compared to stock and the diameter was off by about .01" on the taper side.

Have to admit, we were scratching our heads a few times this PM, almost could not get them off. Nut would not crack for us, just finally opened it up enough so it slipped off the stripped threads.

I wish I could understand why this happened! I'll replace the whole bunch with GM or ARP.

Thanks to my buddy Jim and his knowledge and tools. Jim was a former GM technical trainer, he thinks I got the bolts too hot and they lost temper. Wish I could get the wifes's digital camera working, you would not believe the state of these studs / nuts!

Pete

 

STRANGE :confused:

 

I just had a horrible thought, PeteL...

You do know the C4 has Metric wheel nuts...M12x1.5, to be exact...

But if the NAPA douchebag gave you a Yankee nut/lug, you'd screw it up royal...

 

Thanks for the thought. The threads seem to fit correctly. :confused:

AND a completely stock stud / nut did the same exact thing. I'm going to replace them all, but the mystery continues.

Bent wheels (both front)? Doubt it, it tracks nicely.

Only thing I can think of is the stock bolts / nuts were over torqued one to many times in their life, and the NAPA is just a peice of junk.

Beats me!

Pete

 

does this mean I can't use the MOROSO long studs Summit just sent me? They are 7/16" - 20 x 2 7/8" .560"
long lug nuts are summit open end 1.379 7/16
weld prostars 10x15 w/ 7.5" bs. are going on.
Anyone know?

 

The stocks I pressed out of the car say:

METRIC 10.9

With a "C" in the middle.

 

I twisted off a stud on my '86 a few weeks ago. I was torqueing them down to the required 100 ft. lbs. It was a job getting the old one out. I have been in the car hobby for at least 40 years and I have never had a stud break off like the one on my C4. I have to believe they are not making them like they used to. I got my replacement from a GM dealership. They didn't even have one in stock. I had to wait until they shipped it in from Chicago.

 

I've replaced 5-6 studs that stripped due to previous owner/shop over tightening. I found exact replacements studs from 'Dorman' are much better quality and appear to be zinc plated against rusting. Good luck, Dave :yesnod:

 

I'll be honest with you, Pete...I've never torque-wrenched down a wheel nut in my life...

And a nut bearing directly on an aluminum wheel is something I want to do by feel... :yesnod:

(I really don't know why GM didn't specify steel inserts for the wheel stud holes)... :confused:


[Modified by Rich B., 10:12 AM 5/19/2002]