Chassis Building 101. Ride Height

[RobNoLimit]

I love this thread and have a question. I am designing a full frame/suspension for my 85 C10 and was curious about frame width. Is there a benefit to having a wider frame vs a narrower frame? Or is it best to follow stock width?

Good question. Here is a simple engineering test that we can all understand and remember. I won't drag in all of the math, just an easy demonstration. Think of a chassis as a link between the front and rear suspension. Most forces will be in one of two main areas. 1) flex in the middle - support the chassis on both ends and apply force in the center. Any direction, up, down, sideways, ... and 2) Grab the chassis at each end and try to twist it. Got an image of that? great. Now, imagine the chassis as a link, or a tube for our discussion. Start with a 1 1/4" solid round bar, 10 feet long. Can you bend it? and/or twist it? I bet you could. Now, compare this to a 5" diameter tube with .120" wall thickness, 10 feet long. (Just so you know, these two links have appx the same weight, within 4%, so there is appx the same amount of metal in each). Can you bend it? a little, can you twist it? Not so much. Give that some thought.

The general rule is that 'larger' the dimensions you have - against the forces applied, the better off you will be. A 'wider' chassis resists 'side' forces more. A 'taller' chassis resists 'up' and 'down' forces more. A more 3-dimensional chassis resists 'twist' forces more. OK, this is a really over simplified look, but the concept is true. Yes, X-members, crossmembers, material thickness, gusseting....... all can help, and the overall design can be improved, but as to general width, there you go.