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Old 02-08-2015, 05:38 PM   #10
Vintage Windmills
Vintage 4x4s
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Join Date: Sep 2010
Location: Prior Lake, MN
Posts: 4,305
Re: Frame differences

Good info Tim. The effects of section height are apparent here. The base equation for moment of inertia of a rectangle is 1/12 x base width x height cubed. So adding a couple inches on 6 inches of frame height doesn't add 33% strength, it approximately doubles it. Add material to the height and it gets cubed!

39,000 psi is on the low end for steel, do you know when the grade used by GM increased?

67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades)
67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore )
86 CHV K30 502 th400, apple red NEW
71 CHV K20 350 SM465, ochre (saved work truck)
71 CHV K20 292 SM465, white, tach, PTO, (future project)
72 CHV K20 350 350th, medium blue (project stocker)
01 CHV K2500hd crew, indigo blue

^3 dont run and the others don't see winter either
'86 K30 Cummins "Fireside" thread:
'71 K20 "get driveable" thread:
'72 K20 Build Thread:
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