[Shiny]

That's a good point but I'll have to think about it as my interpretation is different.

The assembly note clearly says "until the screw spins freely", which to me means the threaded section passes completely through both holes. I think the fastener may have a smaller diameter section that is long enough to pass through two thicknesses of strap.

If it were only about avoiding "pushing" the tail during assembly, a clearance hole in the strap would accomplish this. In fact, the repro straps I bought did have a clearance hole. But with the supplied "normal" (fully threaded) screw, the strap was clamped. Getting it to spin freely would mean stripping it which would not be a good idea IMO.

I'll have to go run this special fastener through the old strap and watch what happens.... stay tuned.

[Greg Reid]

Originally Posted by Shiny

That's a good point but I'll have to think about it as my interpretation is different.

The assembly note clearly says "until the screw spins freely", which to me means the threaded section passes completely through both holes..

Yeah, that's the way l interpreted it.

[Shiny]

The fastener is indeed designed to spin freely and NOT clamp the strap.

I could not say if the straps I removed were original or aftermarket. The only marking I found was "W". There definitely was a clearance hole on the fastener entry side of the bend:



The start of threads on the bolt is ~0.7" from the flange. The strap is ~0.095" so there is about 1/2" of "thread-free", reduced-diameter bolt.

3 washers are thicker than the bracket on the car. When I started the bolt, it cleared the outer hole:



When tightened, the threads pulled through the strap and then "exited" the far end without fully clamping the strap. The bolt clearly "spun freely", effectively being a "self-stripping" fastener. The threads that were formed in the strap allowed the bolt to be removed easily:



Net:

- The strap is not clamped "by design"
- The special fastener makes it all happen
- The repro fasteners with full threads don't accomplish the assembly as intended by Pontiac

I'm not too worried about any of this, but as I said, I see this as a very clever system to assure the strap tension is held by the bend and not by the clamped connection. Why? Dunno.....

I can't read the part number for this fastener (#13 on the 1970 assembly drawing). It looks like 399782 ??? Anyone have a clear PN for this?

Mike

[Shiny]

Wonder if the idea was to limit the bend radius in the strap?

If so, fully clamping the strap with the aftermarket screws may "overstress" the strap at the bend? I doubt it would cause any damage but just a thought... I think a general guideline for forming sheet steel was to keep the radius greater than 3 times the thickness ??

Mike