shock bolt torque

[Bob C.]

I got new shocks and bolts for my 66 from Paragon and now have stripped three nuts for the rear top bolts. The AIM shows 40-60 ft. lbs. I set it at 50 and all nuts stripped before that. After the first one stripped they gave me two grade 8 nuts, they stripped too. What should the torque be?

[Bruce B.]

Re: shock bolt torque

Sounds like the hardware they gave you is "made in china".
I ran into the same problem of stripped threads on shackle bolts for the rear springs on a C1.
They, not Paragon, just kept replacing them until I got some good ones.

[Larry M.]

Re: shock bolt torque

I got new shocks and bolts for my 66 from Paragon and now have stripped three nuts for the rear top bolts. The AIM shows 40-60 ft. lbs. I set it at 50 and all nuts stripped before that. After the first one stripped they gave me two grade 8 nuts, they stripped too. What should the torque be?

Bob:

Stop torqueing. Some fasteners are just not meant to be tightened with a torque wrench, and this is one.

I had the same problem with my 1967 car. I got one of the nuts to hold at 40 psig.....it was an original Grade 8 nut. All the replacement ones I tired on the other side failed at around 35 psig or so. Remember this is really a half-nut, so the amount of threads is not sufficient for the 50-60 lb-ft (full nut torque) shown in the Chevrolet Service Manual.

I put a full-sized nut on the bolt as a test, and torqued it to spec with no problem. So it is simply the thinner nut thickness and the metal properties that are the issue.

I simply tightened the replacement nut with a 3/8 inch drive ratchet and called it quits. Suggest you do the same.....or search for another original GM Grade 8 half-nut in good condition.

I have replaced MANY shocks over the years on my cars, and never used a torque wrench on any of the bolts until this last time......and it turned out to be a problem. FWIW, I also rarely use a torque wrench on aluminum, unless absolutely necessary, and I know the CORRECT spec for that particular steel to aluminum joint.

Larry

[Joe L.]

Re: shock bolt torque

I got new shocks and bolts for my 66 from Paragon and now have stripped three nuts for the rear top bolts. The AIM shows 40-60 ft. lbs. I set it at 50 and all nuts stripped before that. After the first one stripped they gave me two grade 8 nuts, they stripped too. What should the torque be?

Bob------

This fastening system included a 7/16-20 grade 8 bolt and 7/16-20 grade 8 THIN nut and 7/16" lockwasher. Any such fastening system that won't hold 60 lb/ft of torque is GROSSLY DEFICIENT.

Here's what I think has happened: most of the thin nuts on the market today are ungraded or grade 2. I'd guess that what's being supplied is such a nut. You can obtain grade 8 thin nuts of the proper size from McMaster-Carr. You usually won't find them in a hardware store, though.

[Dick W.]

Re: shock bolt torque

Almost sounds like your torque wrench is out of calibration. No way a grade 8 nut should have/would have stripped at 50 ft lb

[Joe L.]

Re: shock bolt torque

Almost sounds like your torque wrench is out of calibration. No way a grade 8 nut should have/would have stripped at 50 ft lb

Dick-------


...IF it actually was grade 8.