Chassis Building 101. Ride Height

[RobNoLimit]

Time teaches you lots of things. Back in the '80's we were boxing chassis end to end. (mostly 53-56 F100 and 55-59 chev) These were almost all 'ladder' style frames. This lesson took 6 or 7 years to learn. My own 56 chev p/u (camaro clip and ladder bars, BBC, Th400) started to crack at the joint areas for the crossmembers. - Now it may be true that I put my truck through harder paces than most, but there was still a problem looming. By this time I was in college, learning about harmonics, stress loads and vector forces..... It all made perfect sense. The Ladder style frames, especially the older ones that came with leafs and beam axles, were DESIGNED to flex. Bad roads, heavy loads and cost dynamics forced this. The ladder frame design is basically two dimensional - length - width, not much height. So, you can make it stiffer and stronger, but if you take out the rail flex, it will crack. Now a days, we box the front, from the firewall/front cab mount area, forward to the front core support, and the rear section, about three ft. from the rear shock crossmember forward over the frame kick, and up to the suspension link mounting area (4-link or 3-link). Then we work on creating an 'X' member in the center of the chassis.

[Dr G]

Time teaches you lots of things. My own 56 chev p/u (camaro clip and ladder bars, BBC, Th400) started to crack at the joint areas for the crossmembers. - Now it may be true that I put my truck through harder paces than most, but there was still a problem looming. By this time I was in college, learning about harmonics, stress loads and vector forces..... It all made perfect sense. The Ladder style frames, especially the older ones that came with leafs and beam axles, were DESIGNED to flex.

Well I cannot argue with your experience Rob. I guess the boxing creates stress risers at the cross members.

I do know that my current frame is as you suggest, stock with boxing up front and out back. And I hate it. It is so flexible. I guess that's why you sell custom frames right! Gustave