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| | | | Joined: Jul 2006 Posts: 451 Shop Shark | | Shop Shark Joined: Jul 2006 Posts: 451 | There are four bolts holding the backing plates and steering arms to the spindles. The bottom were 7/16-20 31/4” and held in place with castle nuts and cotter pins. I need 1/2-20 31/4” (they were drilled out to 1/2” to accommodate the disc brake setup).
What are these bolts called? Do they have a specific name when drilled to accommodate a cotter pin? Can I purchase new bolts and drill to accommodate the correct dia. cotter pin, or were the originals hardened and specific grade?
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | They may have been what we now call grade 8 bolts. I don't think you could go wrong
using grade 8 bolts to bolt the backing plates and control arms to the spindle.
McMaster Carr
Grade 8 Cap Screw,
Length 3 1/4",
Thread length 1 1/4" to 1 5/8",
5 to a pack at S8.36
Part number 91257A745,
They also have the short upper ones for the backing plate to spindle if you need those.
Denny Graham
Sandwich, IL
Denny G
Sandwich, IL
| | | | | Joined: Jul 2006 Posts: 451 Shop Shark | | Shop Shark Joined: Jul 2006 Posts: 451 | Thanks Denny,
Grade 8 only makes sense (they came with the disc kit I am removing), as well as pinned castle nuts, is only steering afterall. Just noticed in my teardown pics the OE had castle nuts - I guess they did not have nyloc nuts back in WWII. Just swapping the steering parts back to OE.
How tough is it to drill a grade 8 bolt? I may have in the past and not known about it... just cussed the drill bits for being cheap. I could use a locknut but would be nice to be able to put the castle nusts on it.
Cavebull | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | You should be able to drill them, run the drill slower than you normally would and use a cutting oil on it or something like Tap Magic. It's more about being tough rather than hard but if you get it hot drilling it you can work harden the material.
DG
Denny G
Sandwich, IL
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy cavebull, I would suggest grade 8 Stover lock nuts. Drilling a grade 8 bolt through its rolled threads can be tricky, I have snapped a few drill bits trying this procedure, the metal is not consistant, it has had stresses introduced into it in the thread rolling procedure, I hope that helps. | | | | | Joined: Dec 2001 Posts: 14,522 Moderator: Welcome Centre, Southern Bolters, Legion Hall | | Moderator: Welcome Centre, Southern Bolters, Legion Hall Joined: Dec 2001 Posts: 14,522 | ..if you want to drill Grade 8 and have a machine shop close by take it to them. I have a guy close by and drilled several grade 8's for me for 5 bucks. They have the right stuff!
Bobb, never heard of the Stover lock nuts. Thanks for the heads up. | | |
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