Quote:
Originally Posted by Puglia10
Dang, I didn’t realize a notch would compromise it so much. I do plan to carry/tow around some motorcycles so nothing huge but still…Is there a way to have a notched frame be strong and not have to move the bed floor?
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Whatever height that's removed from the bottom of the rail needs to be added to the top to stay @ what came from GM. There is a minimal amount you can go up under the floor (~1") by removing part of a bed support.
Lots of trucks out there w/c-notches. They might 'work just fine' but they definitely are not as strong as the uncut frame or one w/a step notch that has a full height rail.
The strength is in the height of the rail. However much the notch depth is relates to how much strength is removed. Yes, w/a bolt-in style notch the material thickness is doubled @ the notch area but the strength is in the height not the thickness.
I did the math on the notch depth:
Original rail height @ ~5"
C-notch depth @ ~3.75
3.75/5 = .75 or 3/4 of the rail height removed. My head told me @ most I'll be @ 25%. Then I figured the double thickness + boxing the inside would get me close to stock. It raised the number slightly. Then, add the distance to each spring end & the stress number got worse. I was shocked @ how much it would be compromised when someone who can actually calculate everything including the variables crunched the numbers. The math can be ignored but it doesn't lie.....
I still have those c-notches sitting on a shelf. Used step notch sections from Porterbuilt instead.
I learned all of this when I copied the Western Chassis lay-out & dimensions to build a similar home-built notches for my '64swb project. I actually re-worked my 64's set-up as well & tossed the dually's WC notches in the steel bin in favor of the step notches. Read more about it here:
http://67-72chevytrucks.com/vboard/s...d.php?t=457037