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View Full Version : "C" channel frame, why?

James Hess
06-06-2008, 02:21 PM
just as a question why did GM go with the "C" type frame instead of a fully boxed style? was that just not logical practice at the time? i figure since it gives more strength and rigidity they would have went that rout. have they changed it for the newer models or is it still the same? my truck is a 04.5 just curious as to why they chose this type.
Fingers
06-06-2008, 02:25 PM
Box frames collect crap inside that rots them out. The increase in strength is marginal compared to the increase in weight.
James Hess
06-06-2008, 02:28 PM
Hhmmm ok i was just wondering why. how much stiffer are the "boxed" compared to the "C" channel. and whats the weight diff.
Kevin G
06-06-2008, 04:03 PM
The front 1/3 or1/2 is boxed, just the back isn't. You want it to flex some to keep the frame from cracking. Anything that has no flex will eventually crack from vibration or torsional load. I say that's why most of it's channel and not box.

I was told once that 1/4in channel to boxed is about 1.5-2lbs/ft lighter. Don't know if it's exact but that's what I was told.:confuzeld:
madmaxdmax
06-08-2008, 01:05 PM
Box frames collect crap inside that rots them out. The increase in strength is marginal compared to the increase in weight.

X2 on that note...and it makes sense as well. Weight savings, fuel economy and crumple zones are all part of the engineering.
James Hess
06-08-2008, 10:59 PM
have there been any instances that yall have heard of where they have stress cracks or anything?
madmaxdmax
06-09-2008, 06:24 PM
):hYeah...I bent the fram on my Nissan Titan...HA! HA! That's why I now have a Dmax.):h
James Hess
06-09-2008, 07:12 PM
arent the titans sposed to be fully boxed?
madmaxdmax
06-10-2008, 07:25 PM
....Oh no...not boxed enough IMO. The frame bent just behind the "boxed" section just before the "c" channel section that goes over the axle. Sorry no pics !!
jim87vette
07-03-2008, 03:27 PM
Besides factors mentioned above I bet it saves cost on the steel as well.
duratothemax
07-05-2008, 06:16 PM
Box frames collect crap inside that rots them out. The increase in strength is marginal compared to the increase in weight.

110% agree Jon. Ill take a C channel frame ANY day over a boxed frame. A properly designed and thick C channel frame is just as strong as any boxed frame. People just assume "well its not open on one side, so why would you want a non-boxed frame"

Ive played around with enough and done enough repair/fab work on boxed frames to be very thankful that my frame is C-channel