Does a rollbar eliminate chassis flex?
Thread Starter
Drifting
Joined: Jul 2001
Posts: 1,296
Likes: 0
From: Largo Florida
Does a rollbar eliminate chassis flex?
I have a RD Cross Bar and a Camber Brace. I had to give up my Cross frame due to my custom exhaust. Would a 4 point rollbar eliminate the flex or would you have to go with a 8 point rollbar?
How much better would a 4 point rollbar be compared to the RD Cross Bar? I want to be able to run with the top off and not have to deal with the shakes.
How much better would a 4 point rollbar be compared to the RD Cross Bar? I want to be able to run with the top off and not have to deal with the shakes.
Le Mans Master
Joined: Nov 2000
Posts: 8,745
Likes: 31
From: SE TN
I put a 4-point autopower bar in my ZR-1 and it was easy and clean. It helped to stiffen the car up, but it didn't stop the front from flexing. As for street driving her, the rear view mirror is useless because the bar is in the way. But it does make the car look tuff.
I now have my 89 racer and it has the same bar as the ZR-1. I was thinking about running a bar from the top of the hoop behind the driver to the frame rail on the passenger side near the speaker enclosure to help tie the front and back. I don't want a full out cage becuase that is too much weight and I am only a group II NCCC car.
I now have my 89 racer and it has the same bar as the ZR-1. I was thinking about running a bar from the top of the hoop behind the driver to the frame rail on the passenger side near the speaker enclosure to help tie the front and back. I don't want a full out cage becuase that is too much weight and I am only a group II NCCC car.
Racer
Joined: Jul 2001
Posts: 322
Likes: 1
From: Los Gatos, CA
"Eliminating" all flex while having a street car is a tough thing without having a lot of tubes in your way getting in and out. A weld-in 4 pt helps in the back, but for the front you need more structure to tie it all together. The question is how much stiffness do you want and how much structure and modifications can you live with?
Good luck
Good luck
Thread Starter
Drifting
Joined: Jul 2001
Posts: 1,296
Likes: 0
From: Largo Florida
I could probably make a decision on whether a 4 point or 6 to 8 point if I saw how the tubes would tie into the front. To do that it seems that you would have a lot of clearance issues with interior panels. I have not seen a good picture of that. Maybe it is not possible with a full interior. Probably give up the arm rests and the front speakers.
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Le Mans Master
Joined: Oct 2000
Posts: 6,199
Likes: 9
From: St. louis, MO
I have R-D racing S/T frame Support (aka roll bar) and it helped eliminate a lot of flex. I had the Camber Brace and Cross frame before the S/T, they helped a lot also. But I did notice that the Vette flexes less.
Melting Slicks
Joined: Sep 2003
Posts: 2,270
Likes: 118
From: N. Babylon NY
Hi,
I have a welded-in 4-point roll bar in my 1992. Even with this it still has some flex. The only way to fully cure this is to have the roll bar tied in to the front.
On my car I can jack up the front (right or left) and get the rear wheel off the ground and open and close the doors.
My car seems to flex the most getting in or out of a steep driveway.
Steven
I have a welded-in 4-point roll bar in my 1992. Even with this it still has some flex. The only way to fully cure this is to have the roll bar tied in to the front.
On my car I can jack up the front (right or left) and get the rear wheel off the ground and open and close the doors.
My car seems to flex the most getting in or out of a steep driveway.
Steven
Race Director
Joined: Dec 2002
Posts: 13,348
Likes: 233
From: SCMR Rat Pack'r Charter Member..Great Bend KS
Originally Posted by 2manyfuncars
"Eliminating" all flex while having a street car is a tough thing without having a lot of tubes in your way getting in and out. A weld-in 4 pt helps in the back, but for the front you need more structure to tie it all together. The question is how much stiffness do you want and how much structure and modifications can you live with?
Good luck
Good luck
I'd opine that pretty much says it very well.
Larry
code5coupe
Pro
Joined: Feb 2004
Posts: 641
Likes: 16
From: O'Fallon MO
The Cross Frame and X Frame stiffen up the middle of the frame to correct the flexiing caused by not having the roof on or a T Top/Targa Truss brace installed. The 4pt Roll Bar braces the rear structure of the Vette and is really effective at boxing the twisting of the rear frame from the suspension loads, but its not going to add any structure to the middle of the frame and its torsional stiffness deficiency.
So a C-4 frame with no center bracing and a 4 pt roll bar will probably flex even more since the suspension flexing loads are not being absorbed by twisting the rear of the frame and almost all of the suspension induced twist is applied to the wobbly middle section.
I've got a 91 Z-07 with really stiff springs and roll bars and have the Camber Brace, Cross Frame, and S/T Roll Bar. My car is really tight but the cowl will still shake if I hit a big tar strip or pit hole with the roof removed.
So a C-4 frame with no center bracing and a 4 pt roll bar will probably flex even more since the suspension flexing loads are not being absorbed by twisting the rear of the frame and almost all of the suspension induced twist is applied to the wobbly middle section.
I've got a 91 Z-07 with really stiff springs and roll bars and have the Camber Brace, Cross Frame, and S/T Roll Bar. My car is really tight but the cowl will still shake if I hit a big tar strip or pit hole with the roof removed.
Last edited by hardlight; Jul 20, 2005 at 03:34 PM.
