3956042 shoulder harness retractor mounting bolt

[Edward B.]

Does anyone have a loose 3956042 shoulder harness retractor mounting bolt they can take a picture of and post? I believe it was used from 68-74, but only on the Corvette, and only on the shoulder harness retractors. Paragon and Corvette Central both carry it, but their pictures don't jibe and I need to verify if it's threaded all the way, or stops about 1/4" from the head (shouldered). The AIM is of little use on this one since it only shows a generic bolt.

By the way, I did a search here and the info is also conflicting! Some say there's a shoulder, some say they're threaded all the way and some show a generic hex head bolt!

Thanks
Ed

[Alan S.]

Re: 3956042 shoulder harness retractor mounting bolt

Hi Ed,
Here's a couple pictures of the original shoulder harness bolts from my 71.
I'd describe them as similar to the seat belt bolt except that the top surface of the head is flat while the top surface of the seat belt bolt is SLIGHTLY domed and the un-threaded shank on the shoulder harness bolt is shorter than the un-threaded shank on the seat belt bolt.
Regards,
Alan

[Edward B.]

Re: 3956042 shoulder harness retractor mounting bolt

Thanks Alan. I saw those when I did my previous search.

Ed

[Joe L.]

Re: 3956042 shoulder harness retractor mounting bolt

...some say they're threaded all the way...

Thanks
Ed

Ed-----

Alan's bolts are correct. By the way, bolts for an application and functionality of this sort will almost invariably have an un-threaded shank of some length. I would never expect to see a full thread bolt, even those these are extremely short bolts.

[Edward B.]

Re: 3956042 shoulder harness retractor mounting bolt

Thanks Joe.

Not that I'm doubting you or Alan, but the reason I ask is because there are others that have this bolt (see attached), except without the "nub" at the end. So you can see my confusion. Most seat belt bolts I've ever seen have the thin head like the one I posted. I've never seen a seat belt bolt that has that thick of a head on it. Also, GM seat belt bolts always had thread lock on them to keep them from loosening. You can see what's left of the factory thread lock on the picture I've attached.

HERE'S the thread I'm referring to. Although both have the same LL markings, note the differences in the thickness of the heads.

Ed

[Joe L.]

Re: 3956042 shoulder harness retractor mounting bolt

Thanks Joe.

Not that I'm doubting you or Alan, but the reason I ask is because there are others that have this bolt (see attached), except without the "nub" at the end. So you can see my confusion. Most seat belt bolts I've ever seen have the thin head like the one I posted. I've never seen a seat belt bolt that has that thick of a head on it. Also, GM seat belt bolts always had thread lock on them to keep them from loosening. You can see what's left of the factory thread lock on the picture I've attached.

HERE'S the thread I'm referring to. Although both have the same LL markings, note the differences in the thickness of the heads.

Ed

Ed------


Apparently, the GM #3956042 was manufactured in two different head configurations. Since this difference would not have affected the functionality of the bolt, it could have been done via a change to the 3956042 specs. Or, it could be that the specs allowed for either configuration.

You are correct that most seat belt bolts have a thin head. I believe this configuration is used for clearance reasons that may exist for some applications. However, the shoulder harness bolt would usually not be in need of this provision so that may be by it was produced both ways. These bolts, either lap belt or shoulder harness, are special bolts that have significant safety (and liability) implications. I kind of expect that "L L" is either a manufacturer's ID for a manufacturer that specialized in making these HIGH SAFETY implicated bolts or, perhaps, a headmarking to denote such a bolt.

The bolt pictured in your post appears to me to be a GM #3977719 which was used for the lap belt for 1970-72 Corvettes.

[Alan S.]

Re: 3956042 shoulder harness retractor mounting bolt

Hi,
I tried to add pictures of the lap belt bolts from my 71 to my post with the shoulder belt bolt pictures, but can't.
So, a new post showing both bolt configurations.
Again, the domed head, longer unthreaded shank bolt is the SEAT belt bolt.
This is a mid-January built 71.
Regards,
Alan

[Edward B.]

Re: 3956042 shoulder harness retractor mounting bolt

Thanks again boys. That's a good explanation Joe, and makes sense.

Actually, that bolt picture I posted is for the first generation Camaro. I got it from the Camaro Research Group SEAT BELT REPORT, but I would bet it was used on other models and even other divisions as well.

Ed

[Roger D.]

Re: 3956042 shoulder harness retractor mounting bolt

Folks:

Hope it's ok to resurrect this thread.

I'm still working on the restoration of my '72 coupe and have one good harness bolt and one with bad threads. My harness bolts look exactly as the ones in Alan's picture and by my measurement it is a 1/2"-13x1-1/16". The have the L.L. on the head. I see that Corvette Central has a replacement 3956042 but although the size dimensions are correct, there is no shoulder on the bolt and the bolt head is much thinner.

Million dollar question... any idea where I might find a correct replacement bolt?

If the bolt is unobtainable (it has eluded my searching so) the will the Corvette Central replacement work? Again it has no shoulder. Is the shoulder required for correct functionality?

Thanks.

Roger Dupler