Thread size on Fulcrum Pin

[kurts100]

OK. I'm stumped. Trying to clean out the bushing treads on the A-Arm (Wishbone arm) on a '59 Bugeye. The small hole measures out to 9/16" x 16, which is British Standard Fine thread, but the large measures 5/8" x 16 and I can't find a tap that size anywhere (BSF, BSW, etc.) Was this just some oddball thread size they used in these bushes and fulcrum pins, or am I missing something.

Thanks!

Kurt

 

[Trevor Jessie]

IIRC, It is an oddball size.

 

[SilentUnicorn]

i seem to recall 11/16 ??

you may have seen this

https://mdmetric.com/tech/thddat8.htm

m

 

[JPSmit]

But, isn't it big enough to get a small (dremel sized) wire wheel in there? likely easier and quicker at this point than to find a one off chase

 

[kurts100]

Thanks Guys! It must be oddball size. I rechecked threads per inch and they are 16. When checking 11/16" on the chart, it would have 14 tpi if BSF. Think I will try the very small wire brush on a dremel. My buddy has one.

This has been a royal pain getting the fulcrum pin out. Ended up cutting it with a cutting wheel right next to king pin. Was able to get large end out but had to take A-Arm to machine shop to mill out the small end. We figured when doing that it would just spin out, but of course it didn't. He took it down to just above the threads in the bushing and now I'm hoping I can take the 9/16" x 16 tap and re-tap. Luckily the large bush with the oddball thread just needs cleaned up and I think the wire brush will work.

Thanks again for input!

Kurt

 

[Billm]

No matter what the diameter of the larger side is (it is 5/8") it HAS to be the same pitch (threads per inch) as the other side, otherwise it would bind up when you first insert it and never go fully in.
BillM

 

[James_the_elder]

It's an oddball size but they do exist. The McMaster Carr catalog lists a 5/8 16 hand tap (part # 2595A305). Here's the rub, they are $38.13 each.

 

[aeronca65t]

You can actually buy the brazed-in inserts with that thread (the ones fitted to the A-arms).

I know they are available via the "spares scheme" at the Austin A30-A35 Owners Club.

I forget the contact info for the fellow in charge of their spares. His name is Stan Chatterton. You can find him on ~their forum~.