Basic questions about chassis stiffness
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Joined: Nov 2002
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From: Berkeley, California
Basic questions about chassis stiffness I am aware that the F-body is not as rigid as some cars but I am curious about this because one of the many things I love about my new Camaro is its stiffness. It is by far the stiffest car I have ever driven. I have searched unsuccessfully for an explaination of how subframe connectors make an F-body more rigid. My intuition tells me that a six-point cage far more effectively stiffens a car than any amount of bracing in a single plane. Someone must have have measured chassis flex of our cars with and without SFCs and roll cages. Has such data been published? Any information will be appreciated.
TIA, Gary
<small>[ December 13, 2002, 02:49 PM: Message edited by: Gary Z ]</small>
TIA, Gary
<small>[ December 13, 2002, 02:49 PM: Message edited by: Gary Z ]</small>
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From: F.H,Waterford,Port Huron, MI
Re: Basic questions about chassis stiffness I was not happy at all with the flex of my 01 SS I have done verything posible to stiffen it up. The roll cage is my last hope. A good custom built 6point with rear cross bars! If your car is flexing as you drive on a bumpy raod put your finger in the t-top gap by the window. OR jack the car up by the rear 1" in front of the lower control arm and put a jack stand on both sides you will see a 1/4" or bigger gap opeaning in the door jam!
Re: Basic questions about chassis stiffness Gary,
Since its late (and my posts always get too long) I'll go with the short explanation.
Think of subframe connectors as "sway bars" for the ends of our cars. They reduce chassis flex by resisting twisting (like a swaybar....in a sense). A cage would help even more. (I've had good luck with a BMR STB and SLP weld in SFC's). Hope that helps....at least a little. Good luck.
Since its late (and my posts always get too long) I'll go with the short explanation.
Think of subframe connectors as "sway bars" for the ends of our cars. They reduce chassis flex by resisting twisting (like a swaybar....in a sense). A cage would help even more. (I've had good luck with a BMR STB and SLP weld in SFC's). Hope that helps....at least a little. Good luck.
Staging Lane
Joined: Sep 2002
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From: mass
Re: Basic questions about chassis stiffness I can believe that your f body is one of the stiffest SUSPENSIONS you've driven. But it's chassis is a wet noodle developing more squeeks and rattles every day because of the ridiculous engineering decisions made by GM, and no small part of the reason it's discontinued.There is nothing but a thin layer of stamped sheet metal between the sub frames, and the subs are more flexible than is justifiable. Take out the interior and you'll find the metal connecting front and rear pathetically thin.So the whole car is weak. Look at how many you see with rear quarter panel buckling.The T-top is worse than the hardtop and the vert is more so.And they designed the 4th gen to be a vert!Take a look on this site under KBDD SFC or BMR SFC. Includes some pictures of an intermediate stage in building a full frame f body with reinforced sub frames as well as sub frame connectors, front and rear shock tower bracing and lateral reinforcement.Why not a 8-10 point cage instead? Because on the street, without a helmet, just tagging a curb at 25mph can make those bars lethal. Just realize that radical chassis stiffening does a lot more to improve the perception of solidity and steering accuracy than it does for performance as defined by how fast it'll negotiate a road course.A big reason the chassis never got properly reinforced by the factory is how well a stock car can handle while it's falling apart.
Launching!
Joined: May 2002
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From: Texas
Re: Basic questions about chassis stiffness A cage instead of sub frames will make the chassis more stiff. With a cage you have braces across the car as well as up and down, and more of it.
If GM made the car last as long as we think they should have, we wouldn't be out buying new cars all the time. They need to have it that way. Sucks for us b/c there will be no new f-body's to buy.
If GM made the car last as long as we think they should have, we wouldn't be out buying new cars all the time. They need to have it that way. Sucks for us b/c there will be no new f-body's to buy.
Thread Starter
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From: Berkeley, California
Re: Basic questions about chassis stiffness Thanks for the responses, guys. Scott, I especially appreciate several of your observations. You are undoubtedly correct that it is the suspension rather than the chassis that has made such an impression on me. I have been driving a Suburban for the past ten years and bought a Camaro as a retirement present for myself. Now, after a few months of enjoying the Camaro's lateral g-forces, the Suburban feels like its going to roll over when I change lanes. Also, the safety issues you raised are very important. Those sorts of lessons are what make this site so valuable.
OK, so now I'm convinced that my car is not as rigid as an M1 Abrams, I still don't like the idea of taking my beloved Z down to the local muffler shop and letting someone I don't know weld in something I don't understand. I intend to add horsepower and do a little drag racing. My goal is mid-to-low elevens, so I would need a cage. I also want it to remain a long-distance highway cruiser. You have made me realize that all this might not be feasible. I most want the horsepower and the highway so I may have to forget about the drag racing and the cage. But I digress. I am still interested in measurements of how much various SFC designs reduce static deflection of the F-body. Is all we know about SFCs that they seem to prevent squeeks and rattles?
<small>[ December 15, 2002, 08:40 PM: Message edited by: Gary Z ]</small>
OK, so now I'm convinced that my car is not as rigid as an M1 Abrams, I still don't like the idea of taking my beloved Z down to the local muffler shop and letting someone I don't know weld in something I don't understand. I intend to add horsepower and do a little drag racing. My goal is mid-to-low elevens, so I would need a cage. I also want it to remain a long-distance highway cruiser. You have made me realize that all this might not be feasible. I most want the horsepower and the highway so I may have to forget about the drag racing and the cage. But I digress. I am still interested in measurements of how much various SFC designs reduce static deflection of the F-body. Is all we know about SFCs that they seem to prevent squeeks and rattles?
<small>[ December 15, 2002, 08:40 PM: Message edited by: Gary Z ]</small>
Thread Starter
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From: Berkeley, California
Re: Basic questions about chassis stiffness I have decided to buy SLP bolt-in SFCs. I wasn't aware until today that bolt-ins are available. The fact that no drilling or welding is needed appeals to me. I am very reluctant to do anything irreversible. I will give some thought to making the measurements I was asking about and will post them if they turn out to be interesting. At the very least I will do a before and after 2FAST4U test. Thanks again to all.
-Gary
-Gary
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Launching!
Joined: May 2002
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From: Texas
Re: Basic questions about chassis stiffness Sub frames connect the two ends which as already stated are only connected by thin sheet metal from the factory. This extends the feeling of sturdiness in the frame for a longer period of time. I put mine on when the car was almost brand new, so it had not started flexing yet.
For a good pic of a car that needed them, go to http://www.lgmotorsports.com/catalog...s&car=ls1-fbod
For a good pic of a car that needed them, go to http://www.lgmotorsports.com/catalog...s&car=ls1-fbod
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