1967 GT500 Fan Blade to Clutch Bolts which are the original ones?

[Kent]

I have a C7ZX-A Clutch here and the threads are different to attach the fan. Which bolt is the correct one for this clutch? I have seen 3 different types and I´m not sure.

[TLea]

Correct as in head markings or bolt style/size?

[Kent]

Yes the head markings, the bolt size is also odd from what I figured out.

[TLea]

Recesssed head with lock washer and SEMS is typical but I've seen others. 5/16 18 thread. AMK lists it under 12313 but I've not seen the head marking they have on an original car

[Kent]

Thank you that was in the AMK Kit as well but I have 2 different styles that were also taken from 67 Mustangs and seen on Shelby´s. I will post pictures when I have a minute. Thank you very much Tim.

[T-Bone68]

Is yours a reproduction? I bought a Chris Brown one and the threads did not work with the AMK 5/16-18 provided. Measured 20tpi to me. Closest fit I could find was 5/16-20. This was after he passed and had the memorial sticker, so might have been on only the later attempt to make more.

[Kent]

Exactly the same problem with my clutch. So the repros are not that much concours like they told us. It really sucks. I´m not sure if someone will reproduce them again?

[Road Reptile]

Kent,
Simple to rethread from 5/16 24 to 5/16 18 if it is necessary. At the current price of genuine parts  this is an easy choice. Really the incorrect bolt in fine thread is stronger and when installed would be difficult to see, yet original type and size are the best way to assemble.Would also suggest an application of Blue loctite on the bolts.
R.R.

[Kent]

How do you rethread these when the hole size is the same? Helicoils?

[T-Bone68]

I will just add that other than the one thread pitch being off it is a really nice piece, and I am grateful to whoever it was who worked with the family to keep these available to us after Chris's passing.

[TA Coupe]

Is it possible that someone accidentally used a metric tap to make the threads in the fan Clutch?

    Roy

[Road Reptile]

Kent,
The insert type of repair may be another choice. Take a look at a Time-sert part # 05625
See what you think.
R.R.

[Kent]

I think we need 5/16-18 X 5/8 thread so we need to drill the hole a bit larger to use an insert or?