Tubular Space Frame?, How would you do it? Options

[plymouth37]

So I have been playing with the idea of adding a couple more tubes to the back of the Anklebiter. If you were to replace the back half of a 914 with tubes where would you put them? Here is a rendering of the original cage (red), drivetrain (Grey), and points that need to be tied in (green).
What would you do?

[Brett W]

The 914 chassis is far from good. I think the factory chassis stiffness is on the order of 2500lbs/deg. That is really weak. The factory chassis is a noodle.

As for the tube chassis. I would use 1.5x.045 and 1.5x.065 tubing. No need to get really big. Sheridan's car is probably the best engineered solution. It was done by a professional race car engineer. If you are going to do it I would toss the factory rear suspension and come up with something different. Mount the engine, tranny and suspension to an independent cradle. Then you could fix the 914 problems. The problem isn't flex in the rear of the chassis though. It flexes in the middle. So you will not gain much buy changing the rear. Plus the rear is pretty light because it is all sheetmetal.

[rick 918-S]

The 914 chassis is far from good. I think the factory chassis stiffness is on the order of 2500lbs/deg. That is really weak. The factory chassis is a noodle.

As for the tube chassis. I would use 1.5x.045 and 1.5x.065 tubing. No need to get really big. Sheridan's car is probably the best engineered solution. It was done by a professional race car engineer. If you are going to do it I would toss the factory rear suspension and come up with something different. Mount the engine, tranny and suspension to an independent cradle. Then you could fix the 914 problems. The problem isn't flex in the rear of the chassis though. It flexes in the middle. So you will not gain much buy changing the rear. Plus the rear is pretty light because it is all sheetmetal.

I agree the center of the chassis is where the 914 is lacking. I don't agree the entire chassis is bad. The rear and front sections are very nicely built for a street car. Stiffening where the shock towers crack in the engine bay side and a support for the inside suspension ear are always a good idea. There is alot of overkill being built into 914's. I think it's just because guys like to build stuff.

BTW: I have zero chassis stiffening in my car. Yep. Zero. The rear of the chassis is just fine. Infact I removed the internal brace (boxed structure) just above the rear engine tin that crosses from tower to tower. I have in excess of 350 hp now with a very heavy engine. About equal to the weight of a big block chevy.

If I Ax'ed on a regular basis or raced, I would rethink this. But for a occasional thrashing like Monument National Park or a trip to and from Mount Wilson these cars rock!

It would be interesting to gauge what is happening to the chassis ahead of the rear firewall though... (IMG:style_emoticons/default/unsure.gif)

Dana, Build it like you want it. We love your work. (IMG:style_emoticons/default/popcorn[1].gif)