flexible vs rigid frame

[killakobra]

rigid frames seem to be advertised everywhere today with new truck and it's got me thinking. i can think of advantages to both

stiff:
better handling
body won't tweak
the frame can handle more weight in theory

flexible:
better traction on uneven ground
the frame is less likely to snap

what do you guys think?

[fordman]

i saw a 86 f150 one tiem that the frame had cracked in two. right about the steering box area on our trucks would be.

[SteveC]

rigid frame your just asking for stuff to break

example: when people put a flat bed on they bolt the bed down in like 8 places all down the side of the frame on each side. pretty much taking all flex out of the frame. The frame broke right behind the cab cause that was the only flex the frame had so the frame broke.

[knightfire83]

On an old episode of Trucks! Stacey was in a big rig shop talking about semi tractor frames. They said the frames were a large C channel type in order for them to flex, otherwise on takeoff the frames would snap from the force.

Next time you see a Semi truck loaded down look how much the frame flexes when they take off from a dead stop, it's quite a bit.

[fireguywtc]

What are you building on or off road? Obviously even a stiff frame needs some flex or ability to fex, but I think you already knew that.

[killakobra]

On an old episode of Trucks! Stacey was in a big rig shop talking about semi tractor frames. They said the frames were a large C channel type in order for them to flex, otherwise on takeoff the frames would snap from the force.

Next time you see a Semi truck loaded down look how much the frame flexes when they take off from a dead stop, it's quite a bit.

i've seen a few videos of semi's twisting 30 degrees on take off.

What are you building on or off road? Obviously even a stiff frame needs some flex or ability to fex, but I think you already knew that.

well of course. otherwise you would lose traction.

why do they stess full boxed frames latly? it seems like bumps manage fine with c frames. maybe it's because they are aluminum now.

[ForingaMex]

Check out this video.
http://www.youtube.com/watch?v=Jxv2hOlFav4&feature=fvw
Talk about frame twisting.

[killakobra]

yea. i've run across this a few times

[TNIceWolf]

A boxed frame has been around a long time. But essentially it is used in application where you want to limit the twist of the frame under power. A general use off road vehicle doesnt need it. Something as severe as a rock crawler might.....you would give up the flex to allow for the srength and less breakage in a remote terrain. Just my opinion from working with military vehicles.

[Caseys71]

I think that essentially you would want to build a frame with a bit of both,varying on application, just as most have said. If you want rigidity and strength then you want to go for a rigid frame, which would be stronger but easier to snap due to the lack of flex and flexibility comes in handy if you want traction and to have a bit of play in the frame to avoid snapping.

A boxed frame has been around a long time. But essentially it is used in application where you want to limit the twist of the frame under power. A general use off road vehicle doesnt need it. Something as severe as a rock crawler might.....you would give up the flex to allow for the srength and less breakage in a remote terrain. Just my opinion from working with military vehicles.

And to add on to that many times people also box in frames on older vehicles with a C-Channel type frame whenever they are customizing things and bolting them vertically through the frame to keep the top and bottom lips of the C-Channel from bending in such as what carcrafter is doing with the crown-vic suspension swap where he did so on the frame nearest the cross-member.