Pinion Gear Castle Nut - size?

[meteorpete]

Can someone tell me the size of the castle nut used to hold the pinion gear on the driveshaft? I've got a cracked nut (2 actually) that I believe was self caused when I used a large pipe to pop the pinion off the driveshaft. I'm in Canada and am going to try to source locally if I can so I can finish this job sooner rather than later. Thank you!

[Y-Blockhead]

Originally Posted by meteorpete

can someone tell me the size of the castle nut used to hold the pinion gear on the driveshaft? I've got a cracked nut (2 actually) that i believe was self caused when i used a large pipe to pop the pinion off the driveshaft. I'm in canada and am going to try to source locally if i can so i can finish this job sooner rather than later. Thank you!

⅝-18 castle nut. Ensure the nut or cotter doesn't hit the ring gear.

[meteorpete]

Originally Posted by Y-Blockhead

⅝-18 castle nut. Ensure the nut or cotter doesn't hit the ring gear.

Thank you!

[Phil Brown]

If I rember correctly the nut also has a rather low profile to it for clearance to the ring gear. Also when you spread the cotter pin do it sideways around the nut wrench flats, not over the end of the nut. Vert tight clearance between the end of the drive shaft/nut and ring gear

[Bob Bidonde]

The castle nut is special and it is listed with the drive shaft. A-21892 has 5/8-18 threads, it is 23/32 x 15/16 in size and it is hardened (heat treated). 15/16 is the wrench size & 23/32 is the height of the nut.
Many years ago I experienced this nut departing the shaft and getting jammed into the ring gear as my Coupe was running at speed. It totally destroyed the differential.

[Joe K]

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A "Grade 8" nut would be the nearest modern equivalent.

Grade 5 is what most suppliers handle in English nuts. Metrics are available as Grade 8.

This includes McMaster, Grainger, even Amazon who is surprisingly reluctant to give specifications on nuts.

Maybe best to buy a nut from a Model A supplier? These come trimmed to the size required - but they don't give you anything other than "This is the right one - our reputation assures you."

Still, vendors do what they can. Snyder's T-2598 $3 each. Advertised for model years 09-31.

Joe K

[meteorpete]

Thanks for all the input - much appreciated. I am in Canada and we Canadians do what we have to do to get parts from great places like Snyder's. But, when a small hardware item is needed it is best to source locally due to timing and cost.

[Bob Bidonde]

I would opt for an original nut from a junk differential.