car frame

A C-frame would be the weakest in my opinion. The fully boxed or square tubing frame could be by far the strongest but also would be the heaviest. So in the long run a well built frame using tubular steel would be the lightest and strongest and could be far more flexable. That is if you are building one from scratch. If you are modding an exiting frame you would 'box' the C (or U shaped) steel to add more strength.

Rather an ill defined question.

Depends on how you define 'better'.... cheaper? prettier? stronger?

But on a strength/weight basis I'd say tubular would win.

Cost to manufacture .... C frame (assuming I understand the term..)

Prettier.... tubular.

thanks for your response, my goal is to build from scratch my own 3 or 4 wheeled electric vehicle, i have children so safety is primary concern , i want to know which is the safest frame for a car. ?@ hexagonal tubing, does it exist, does the triangle (as in trusses) add strength to the frame? ?@ welding which is better MIG, TIG ... ?@ tubing dia. & thickness- i've seen 1" & 1¼". thanks for your input.

The strongest, lightest frame is box made from hydroformed steel pipe or tubing. This forming process also allows the tubing to be deformed to simulate stronger structural shapes such as I-beams, channels, etc. as required.

does anyone know which is a better car frame? is a tubular frame stronger than box or c-frame? thanx

Asssuming you are not mass producing these cars, hydroforming is probably not going to be your first choice$$$$$$$$$$. If your frame will include a roll cage to accomodate lots of triangulation in its design (preferred), use tubular steel, preferrably DOM or welded round tubing, although round is more difficult to fit up than square, it looks better and has better torsional resistance. If you are simply running two frame members along the length with out any connecting triangulation points to a higher member (like a roll cage) then I would suggest rectangular structural steel tube. You can use rectangular lower members with round for the rest (see Nextel Cup stock cars). For an inexperienced welder, a MIG is way better, but TIG is the best. If you plan on using 4130 Chromium Molybdenim steel tubing, TIG is a must, and should be welded by a pro.

GS

If i were you id stick to your basic carbon steel rectangular tubing. Its common, strong cheap (relatively)and easy to weld. The shape and material has already been proven in every area of the automotive industry so no R+D to be done. Plus it is easier to find redly available parts to work with it. MIG is easiest to learn, fast and consistent.

Yup, I'll raise my paw and vote with that suggestion!