C3 Seat Belt Bolts

[Joe L.]

Re: C3 Seat Belt Bolts

Hi Joe,
The 71 AIM lists 3977719 as the part number for the seat belt bolt and 3956042 as the part number for the shoulder strap reel mounting bolt.
Regards,
Alan

Alan------


Yes, I recollected the part number incorrectly. It is 3977719. I'll correct that.

[Larry E.]

Re: C3 Seat Belt Bolts

Tom-------


Yes, apparently for 1978 GM began using metric bolts for the seat belt anchor bolts. 1978 marked about the beginning for "metricification" of US-manufactured vehicles. Thereafter, the process proceeded inexorably.

I believe there's one last bastion of US/SAE size bolts in the GM stable for PRODUCTION vehicle components. Does anyone know what it is?

Joe: My guess would be the "Crate Engines" they offer for the S/B/C and B/B/C.(Not the Chevy LS Type Engines) Larry

[Larry H.]

Re: C3 Seat Belt Bolts

Joe, The 2014 "G" van with the 4.3 V/6 engine still uses US/SAE bolts for engine parts such as heads, valve covers, intake and exhaust manifolds, oil pan, front cover, etc.

[Alan S.]

Re: C3 Seat Belt Bolts

Hi Joe,
This thread has gotten me to think more specifically about the installation of the bolts in St.Louis and how what the workers were being asked to do might have affected the configuration of the bolt.
First the shoulder belt/reel bolt. There was a fairly large pre-cut (it appears) hole in the wheel well carpet which would have made starting the bolt quite straight forward. An un-tapered bolt would be no problem.
For the 4 seat belt bolts (1971) there was no underlayment in the area where the bolts threaded into the nuts, BUT, the hole in the carpet appears to have been individually 'poked' based on just how the carpet was installed. A tapered bolt would help in getting the bolt through the carpet and started in the nut; but a non-tapered bolt was spec'd in 71.
Pics: underside of original wheel-well carpet/underlayment showing the pre-cut hole, and, original underlayment laying in the passenger's side showing the area cleared out for the inner seat belt mount.
Regards,
Alan

DSC_0492.jpgDSC_0953.jpg

[Joe L.]

Re: C3 Seat Belt Bolts

Joe, The 2014 "G" van with the 4.3 V/6 engine still uses US/SAE bolts for engine parts such as heads, valve covers, intake and exhaust manifolds, oil pan, front cover, etc.

Larry------


Yup. That's the one. It's on its last gasp, though.

[Joe L.]

Re: C3 Seat Belt Bolts

Joe: My guess would be the "Crate Engines" they offer for the S/B/C and B/B/C.(Not the Chevy LS Type Engines) Larry

Larry------


Yes, many of the crate engines do use US/SAE fasteners. However, those engines are not PRODUCTION engines (i.e. not engines used on the production line in new vehicles).

[Jerry B.]

Re: C3 Seat Belt Bolts

Joe, MY SEPT. 21, 1968, has the exact same bolt you have shown for the outboard seat belt.

[David H.]

Re: C3 Seat Belt Bolts

Both upper and lower seat belt bolts on my 1 April 1980 have a slight taper, but no "pilot" configuration as in your post. Both are 12mm (metric-blue stain) T-50 torx head, 1.75 t/mm. Seat belt bolt (stamped "A2") is 33.4mm long (40.3 overall) with a 14mm dia smooth section 15.3mm long. The shoulder harness bolt (stamped "S2") is 25.0mm long (32.7mm overall) with threads the entire length of the bolt - no smooth section.