Should I race?
04-16-2014, 05:42 PM
#24
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But beginning with the C5 Corvette, Corvettes have such massive frames that this is just a whole new level.
Now, I do have some bad news about the effectiveness of roll cages in unibody cars. A Mustang at Nelson Ledges got an inside wheel off the track, nosed-in, did a forward flop while coming to a stop, and the feet of the AP roll cage poked through the floorpan. (Then my idea for improving roll cages in unibody cars is to have down-tubes from the door bars to the rocker-panel / door-sill areas.)
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Last edited by B Stead; 04-16-2014 at 05:51 PM.
04-16-2014, 06:24 PM
#25
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4th gens do more than fine with road racing.
Now, I do have some bad news about the effectiveness of roll cages in unibody cars. A Mustang at Nelson Ledges got an inside wheel off the track, nosed-in, did a forward flop while coming to a stop, and the feet of the AP roll cage poked through the floorpan. (Then my idea for improving roll cages in unibody cars is to have down-tubes from the door bars to the rocker-panel / door-sill areas.)
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04-17-2014, 01:00 AM
#26
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I don't think that less than 2 degrees of body roll, at maximum lateral traction, could be reached with a car that has average chassis flex. The stiff suspension has to have something to work against.
The car (1970 Trans Am) probably had a very strong K-member to go along with its very large front swaybar. But here's another tip, the K-member needs to visibly tie into the rocker panels because there is not much of a front bulkhead between the rocker panels on most unibody cars.
A Corvette runs a frame channel from rocker panel to front suspension. That's the hydroforming shaping of the frame channels and no front bulkhead needed.
Some 1960's cars were unibody-on-a-frame and probably extra heavy. (I suppose that's high seat mounting locations since the frame channels couldn't swing out to the rocker panels.) Then the stock car rules and builders took the unibody off the frame and built a roll cage on the frame in its place. What they gained was the front suspension geometry and of course kept the frame channels
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The car (1970 Trans Am) probably had a very strong K-member to go along with its very large front swaybar. But here's another tip, the K-member needs to visibly tie into the rocker panels because there is not much of a front bulkhead between the rocker panels on most unibody cars.
A Corvette runs a frame channel from rocker panel to front suspension. That's the hydroforming shaping of the frame channels and no front bulkhead needed.
Some 1960's cars were unibody-on-a-frame and probably extra heavy. (I suppose that's high seat mounting locations since the frame channels couldn't swing out to the rocker panels.) Then the stock car rules and builders took the unibody off the frame and built a roll cage on the frame in its place. What they gained was the front suspension geometry and of course kept the frame channels
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Last edited by B Stead; 04-17-2014 at 01:16 AM.
04-17-2014, 07:24 AM
#27
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youre saying 'probably' a lot and assuming many things. have you any proof that your quoted trans ams had extra bracing or not.
and to reiterate, body roll is NOT chassis flex. they are two different things and one can not be a benchmark to the other. you can easily build an absolutely rock solid chassis with ZERO flex, and still have massive amounts of body roll. ever see a 50s car take a tight turn? that heavy frame is NOT flexing, but the body is rolling plenty.
enough comparing fbodies to vettes. theyre two completely different cars. if youre such a vette fanboi, why are you ever here, instead of on a vette forum? be a typical yuppie, and buy a vette to fit in with everybody else.
and ive seen the vid of the rolled mustang. first, mustangs do suck. second, its been proven the cage was improperly installed. third....**** happens.
youre using that ONE extreme example as gospel to any and all cars......well i remember watching a NASCAR race (who makes the absolute strongest, toughest, most professionally made cages in motorsports) where a car was hit, literally ripped in two, leaving the driver completely open and exposed. does that mean every and all caged cars are unsafe, because of that ONE incident?? does that mean that every single NASCAR builder is doing it wrong?
or how about the INDY race where the front end of the car was ripped off, leaving the drivers legs hanging out during a crash. he lost his legs, of course. does that mean every single indy car is unsafe and fundamentally flawed, because of that ONE incident??
and to reiterate, body roll is NOT chassis flex. they are two different things and one can not be a benchmark to the other. you can easily build an absolutely rock solid chassis with ZERO flex, and still have massive amounts of body roll. ever see a 50s car take a tight turn? that heavy frame is NOT flexing, but the body is rolling plenty.
enough comparing fbodies to vettes. theyre two completely different cars. if youre such a vette fanboi, why are you ever here, instead of on a vette forum? be a typical yuppie, and buy a vette to fit in with everybody else.
and ive seen the vid of the rolled mustang. first, mustangs do suck. second, its been proven the cage was improperly installed. third....**** happens.
youre using that ONE extreme example as gospel to any and all cars......well i remember watching a NASCAR race (who makes the absolute strongest, toughest, most professionally made cages in motorsports) where a car was hit, literally ripped in two, leaving the driver completely open and exposed. does that mean every and all caged cars are unsafe, because of that ONE incident?? does that mean that every single NASCAR builder is doing it wrong?
or how about the INDY race where the front end of the car was ripped off, leaving the drivers legs hanging out during a crash. he lost his legs, of course. does that mean every single indy car is unsafe and fundamentally flawed, because of that ONE incident??
04-17-2014, 07:38 AM
#28
Well, the 1970 Pontiac Trans Am was road tested in car magazines as having 1.9 degrees of body roll at 0.80G. So I would expect that, that car had more chassis bracing than some of the other Firebirds and Camaros. And sure, if racing a unibody car just add bracing.
But beginning with the C5 Corvette, Corvettes have such massive frames that this is just a whole new level.
Now, I do have some bad news about the effectiveness of roll cages in unibody cars. A Mustang at Nelson Ledges got an inside wheel off the track, nosed-in, did a forward flop while coming to a stop, and the feet of the AP roll cage poked through the floorpan. (Then my idea for improving roll cages in unibody cars is to have down-tubes from the door bars to the rocker-panel / door-sill areas.)
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But beginning with the C5 Corvette, Corvettes have such massive frames that this is just a whole new level.
Now, I do have some bad news about the effectiveness of roll cages in unibody cars. A Mustang at Nelson Ledges got an inside wheel off the track, nosed-in, did a forward flop while coming to a stop, and the feet of the AP roll cage poked through the floorpan. (Then my idea for improving roll cages in unibody cars is to have down-tubes from the door bars to the rocker-panel / door-sill areas.)
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The bolt in cage was installed wrong in the the Mustang, I read a lot on that incident. That car was built as a "show piece" and was never intended to be on track.
My car is rigid with a Wolfe 4 point bar and frame connectors, the floor is sandwiched with 1/8 inch plates.
A Camaro is a great platform......for the money.
04-17-2014, 11:41 AM
#29
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But a roll cage simply bolted to a unibody floorpan is really not much of an improvement. The bigger K-member development is better for chassis stiffness.
Well, tie the roll cage into the door-sill / rocker-panel areas and that would be significant.
See, my posts are only about chassis stiffness. I was suggesting that if the roll cage could poke through the floorpan then the roll cage probably wasn't adding to chassis stiffness either. The floorpan could simply flex or pinch near the edges of the roll cage plates
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Last edited by B Stead; 04-17-2014 at 12:08 PM.
04-17-2014, 01:02 PM
#30
No, it was AP roll cage which is widely approved and will only go in one way.
But a roll cage simply bolted to a unibody floorpan is really not much of an improvement. The bigger K-member development is better for chassis stiffness.
Well, tie the roll cage into the door-sill / rocker-panel areas and that would be significant.
See, my posts are only about chassis stiffness. I was suggesting that if the roll cage could poke through the floorpan then the roll cage probably wasn't adding to chassis stiffness either. The floorpan could simply flex or pinch near the edges of the roll cage plates
.
But a roll cage simply bolted to a unibody floorpan is really not much of an improvement. The bigger K-member development is better for chassis stiffness.
Well, tie the roll cage into the door-sill / rocker-panel areas and that would be significant.
See, my posts are only about chassis stiffness. I was suggesting that if the roll cage could poke through the floorpan then the roll cage probably wasn't adding to chassis stiffness either. The floorpan could simply flex or pinch near the edges of the roll cage plates
.
What I read was the car was built to be a show piece, to sit and show what they sell. It was never built to be put on track, they were coaxed into getting on track with it.
If you think that cars failure will happen to every unibody car with a bolt in bar you are wrong.
Aftermarket K members do nothing for chassis stiffness, absolutely nothing.