Bolt size clarification...

3

329s

Senior Member
When looking at bolt A-20740 Engine rear support bolt IN THE PARTS PRICE LISTS, which gives the size as 5/16-24 (2 x 1-3/8)...what does the "(2 x 1-3/8)" mean?

I know it has to do with the length of the bolt, 1-3/8 I think...but what does the "2" mean?

These are the bolts that attach the Engine rear support to the frame...three (3) per side.

Thanks.

Pluck
 
Last edited:
Pluck,
If this is for the AA the 1932 parts book shows bolts are 21492-S2 5/16" -24 x 1 7/8" for 28-30
and 22245-S2 5/16"-24 x 1 1/2" for 30-31.

Bob
 
The S2 is the finish of the fastener. I believe S2 is just oiled. Ford still uses the same way of calling the finish today.
 
could it be 'quantity 2 required' my July1, 1931 parts price does not show the 2 in the description only: 5/16-24 x 1-3/8
 
I recently had to buy some spare taps and bought class 3 taps, which gives a threaded hole much more precision than the Craftsman tap I was using, which I'd guess might have been a class 1 tap.
 
I believe Tom is correct that the 2 is a class fit. When buying and using taps for example we would use GH3 taps which are designed to give 75% thread when used with the proper tap drill size. When building tooling which would get heat treating we would tap with GH5 taps which cuts the thread oversize. Class 1 fits would be a fit where the bolt or stud would be a tight but, useable thread and would appear to give an unshakeable type fit. Years back Champ used to market oversize studs to be used on rear axles because the originals would be too loose after a time in service. Always examine your taps or when purchasing taps. I have seen guys trying to start left hand taps and get nowhere, remember some A horns use a left hand nut on the armatures.
 
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