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dsraven · 01-17-2018, 02:37 PM

I think, if ,memory serves me, that the AD trucks have a pivoting diff connection to the springs to help alleviate the length issue with the torque tube as the truck goes over bumps or load is added. that is the issue with the frame mounted bars that don't pivot in the same axis as the u joints and spring pivots. the old "slapper" style of traction bars didn't have to worry so much about that because they only connected to the one end. just draw out a quick diagram with the attachment points and see how moving the diff up and down will bind the suspension. or mock it up with some wood scraps on a piece of plywood. screw the pivot points down but not so tight they can't move. then move the diff up and down to see what happens. the 4x4 guys have it even worse, if they use some sort of link, because they generally add blocks between the diff and the springs so, as power is applied and the diff tries to wind up, it exaggerates the pinion angle and the length of the driveshaft. lots of issues with driveline vibration under load, bent shocks, broken u joints driveshafts that pull out of the transfer case slip joint or other problems with the 4x4 lift guys. go figure. it pays to mock things up and run the suspension through a full travel to look for problems.
just my 2 cents.

01-17-2018, 02:37 PM	#12
dsraven Registered User Join Date: Nov 2010 Location: calgary alberta Posts: 8,501	Re: Traction bars I think, if ,memory serves me, that the AD trucks have a pivoting diff connection to the springs to help alleviate the length issue with the torque tube as the truck goes over bumps or load is added. that is the issue with the frame mounted bars that don't pivot in the same axis as the u joints and spring pivots. the old "slapper" style of traction bars didn't have to worry so much about that because they only connected to the one end. just draw out a quick diagram with the attachment points and see how moving the diff up and down will bind the suspension. or mock it up with some wood scraps on a piece of plywood. screw the pivot points down but not so tight they can't move. then move the diff up and down to see what happens. the 4x4 guys have it even worse, if they use some sort of link, because they generally add blocks between the diff and the springs so, as power is applied and the diff tries to wind up, it exaggerates the pinion angle and the length of the driveshaft. lots of issues with driveline vibration under load, bent shocks, broken u joints driveshafts that pull out of the transfer case slip joint or other problems with the 4x4 lift guys. go figure. it pays to mock things up and run the suspension through a full travel to look for problems. just my 2 cents.