Propshaft bolts/nuts size?

[PhilBell]

Can anyone confirm the correct size for the propshaft flange nuts and bolts please?

I need to fit new nylocs after a the last axle-out job. The ones on there are 9/16in but my parts supplier stocks 3/8in for this application, which seems way too small for the job.

[johnney]

3/8" sounds right, they are certainly not 9/16" What did you measure the head size?

[mgcjag]

Hi Phil....try to get yourself a copy of the SC parts...6 cylinder E type catalogue......lost of diagrams/part numbers and specifications.yoy can pick them up on ebay....they show 3/8unf and half locknuts....cannot remember now but think the full size locknuts might be too thick...

[mark10337]

C19827 bolt with a C8737/3 nut (3/8" half nyloc)

[abowie]

I suspect the source of the confusion to be nomenclature.

The bolts are 3/8" UNF. This means that the diameter of the bolt is 3/8"

The head size on these is 9/16"AF. So the spanner to fit the head is 9/16" across the flats (AF) of the hex head.

So.. 9/16" AF and 3/8" UNF are one and the same from a practical point of view.

[PhilBell]

Thanks for the clarification - the 3/8 UNC nuts do indeed have 9/16 AF heads.

[johnney]

Propshaft bolts should be UNF not UNC.

[PhilBell]

You're right. Too much haste here, didn't read previous posts properly. I blame the stress of contemplating a fourth rear axle removal (for an unrelated problem). Hmmm...

[JagWaugh]

Dropping the IRS for the fourth time? Never mind bolts, use drilled pins and cotters!

[ETTony]

I have just reassembled the back end of mine.

BTW these bolts do have a shoulder so they are a snug fit in the prop shaft holes.
So you do need the correct bolts not simply generic bolts.