Body twist

[85 Cutlass Brougham]

85 and broke....I think you'll agree the strength of the frame is far greater than the sheet metal of the body. In order to brace the body to stiffen the frame you'd basically have to mount the body directly to the frame and add so much bracing, since the body is only as stiff as it's weakest points the added weight, the car would weigh a ton.

That was my point. With almost solid mounts the car essentially becomes unitized. It is also very hard to take out all of the torsional flex in just a flat structure. Both pieces do compliment each other. I do agree that you need to stiffen the frame as well as the body, and that the frame will have a larger effect than the methods used to stiffen the body shell, but the body will still have an effect.

 

[pontiacgp]

85 and broke....I think you'll agree the strength of the frame is far greater than the sheet metal of the body. In order to brace the body to stiffen the frame you'd basically have to mount the body directly to the frame and add so much bracing, since the body is only as stiff as it's weakest points the added weight, the car would weigh a ton.

That was my point. With almost solid mounts the car essentially becomes unitized. It is also very hard to take out all of the torsional flex in just a flat structure. Both pieces do compliment each other. I do agree that you need to stiffen the frame as well as the body, and that the frame will have a larger effect than the methods used to stiffen the body shell, but the body will still have an effect.

I agree if the body is mounted directly to the frame....but if the frame is not substantially strengthened/stiffened before directly mounted to the body I would suggest the glass windows be replaced with lexan....

 

[shotgun]

Why do convertibles get beefier frames the "roofed" cars?

 

[pontiacgp]

Why do convertibles get beefier frames the "roofed" cars?

what convertibles are you referring to?

 

[shotgun]

"what convertibles are you referring to?"

ANY convertible, be it A-body (g-bodys big brother) or F-body(subframe), don't know too much about the new fangled stuff (post 1978). :lol:

Why do convertibles get beefier frames the "roofed" cars?

To answer my own question, because they lost the additional structure from the roof/body.

 

[pontiacgp]

Your right about the A body having a beefier frame but for a convertible they used different body bushings and the beefier frame had nothing to do with the loss of any body strength, it was beefed up to stop the cut off B pillars from rattling. The also beefed up the pillarless hardtops for the same reason. You'll also notice that for T-tops there is nothing done to the frame even though the a pillar is not connected to the B pillar. Another thing your probably aware of there are countless G bodies out there missing a number of body mount bushings and bolts that have no effect on the car and no recall was ever put out due to the missing body bushings and bolt. The F body have frame connectors when it turned into a convertible. We just built a 2nd gen Camaro for our racing this year and I was shocked at the amount of double layer sheet metal in the roof. rocker panels and B pillars that make up for the lack of a chassis in the car. In the 60's buick has a fully boxed frame for all of it's line skylark cars and in the late 60' one of the telltale signed of a true Chevelle SS is the boxed frame.

I'm not disagreeing with you that in theory a stiffer body adds to the stiffness of the frame but in all practicality you'd have to build up the body comparable to the F body to have an appreciable effect. The additional weight of bracing the body and the position of that weight being far above the center of gravity will negate it's effectiveness. I trust you'll agree The addition of any non sprung weight is most effective as low as possible and inside the wheels. In our circle track car we are not too concerned about the body flexing since we don't add any weight unless if is necessary. I know we are driving street cars but the same principle can be applied.