Help! Jeep flywheel nut

[Piston Broke]

Whilst torquing up the nuts that hold the flywheel onto the crankshaft on my Jeep, one of then stripped out (just the nut, not the bolt, fortunately, otherwise it would have been crankshaft out!).  Mine is a French bitsa, and at least some of the engine, flywheel included, is of WOF manufacture.  There are six bolts that hold the flywheel on, two larger fixed dowel bolts and four  smaller 3/8" UNF bolts.  The nut that has stripped is one of these smaller 3/8 ones.  On wartime Jeeps it would seem that these were 9/16 AF nuts, as normal with a 3/8 UNF thread.  However, it would appear that the WOF engine (and possibly the M51?) has chunkier nuts.  Although the thread is still 3/8, the nuts are 5/8 AF.  I have tried all my usual suppliers (Jeeparts, Dallas etc.), but they only stock the smaller 9/16 nuts.  Does anyone know where I can get a replacement 5/8 nut?  I suppose if push comes to shove I could replace them all with the smaller nuts, but I'd rather not mess around with the original spec if I can avoid it, as I guess they were that size for a reason.

[attleej]

I could make six 3/8 UNF nuts with 5/8 A/F hex but they would be in EN1A which would be OK if the thread length was not short.

John

 

[Piston Broke]

Thanks for that.  However, I believe they are hardened, although I couldn't be specific about the spec.  I'll measure the thread length and give them a scratch test with a scriber over the weekend, just to get a feel for the hardness and get back to you.  Meanwhile, if anyone can suggest an off the shelf source to save us the hassle, please drop me a line.

[Piston Broke]

Problem solved; a friend of a friend had a couple of the nuts knocking around.  Thanks for the offer though John, much appreciated.