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choosing bolt sizes & strength for uca/lca

4x4JeePmaNthINg

NAXJA Forum User
Location
Colorado
Ive been digging through build variations If I was to do a DIY 3 link long arm.



One focal point on my plate is the front d30 UCA mount which normally runs a 7/16 bolt. JJ makes an upgraded 1/2" bolt press in joint which is what I was thinking of adding.

In my findings, some vendors kits use 9/16 bolts on UCAs.
as it stands my upper joint set up would be a 9/16 frame side and a 1/2 on the axle.
about 3600ftlbs of shear strength difference.

I've never really read about this topic when people design/ build their rigs, but is there some kind of guideline to choosing hardware size for your builds uses?

I was using this for looking at bolt strength differences:
https://www.fastenal.com/en/84/load-calculator

Should I mainly be concerned with shear strengths, or otherwise?

Does anyone have info or ballpark on what kind of forces the LCAs/UCAs could expect to see?
 
I run 9/16" on my arms. The benefit of a 9/16 is that mostly all the flex joints that you can get have that size hole. I have johnny joints on my upper and lower arms and run 9/16".
 
If you were doing a 3 link, I'd want 9/16 at a minimum everywhere.

With a 4 link 7/16 or 1/2 on the uppers would be very adequate.
 
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