Rollcage update (pics)
Thread Starter
Burning Brakes
Joined: Mar 2005
Posts: 1,139
Likes: 0
From: Salina Kansas
-Yeah guys, the hoop behind me is a done deal, best plan or not at this point. It's good to hear that tech isn't saying anything, would have been surprised if they did though really as I have combed the NHRA rulebook several times and there is no mention whatsoever as to where the main hoop 'must' be mounted. I hope to work on it some more tomorrow, needs a little 'fitting' still to get proper headline clearance. My goal tomorrow is to get the seat brace welded in, get everything fitted, then prime/paint/clearcoat. May weld in the hoop Sunday and then I work on the swing out bar...
I'll try to get a few pics posted tomorrow.
Great Chris, post some pics when your done. I got sidetracked with the new body mounts/frame repair on #4's etc. Took a lot of time on that, but it turned out well.
I'll try to get a few pics posted tomorrow.
Great Chris, post some pics when your done. I got sidetracked with the new body mounts/frame repair on #4's etc. Took a lot of time on that, but it turned out well.
Instructor
Joined: Nov 2006
Posts: 173
Likes: 0
From: hampden ma
hey dave...shud i be running a rollbar on my bb vert,stroked,475+hp to limit frame twist?
is this just nhra req. or just a good idea anyways? thanks
fred...ps never be ashamed of your welding... if you can do it at all you're 150% better than most
is this just nhra req. or just a good idea anyways? thanks fred...ps never be ashamed of your welding... if you can do it at all you're 150% better than most
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
i'm drawing it out on paper right now.
I did my rear braces much different than i've seen you guys do them. Instead of running it straight back i put an angle on it. In addition, it attaches to the top of the hoop rather than 1/2 way up. This in my opinion creates some effective triangulation side to side and maybe some less effective triangulation front to rear.
If you envision force trying to bend one side of the frame after the kickup in the upwards direction, that force will create a vector on that rear support in turn pushing in several directions on the hoop. The other rear brace acts as a restraining arm. So if you envision force being in 3 directions:
1. pushing towards the front of the car.
2. pushing towards the side of the car.
3 pushing up on the hoop
I think this creates a stronger overall system providing perhaps some stiffening for the rear of the car.
The disadvantage is obvious. Some rear window obstruction. The inspector has not said anything for the past 2 years. If you think about how much window a vert has, i still think i have at least that much view.
When TT wakes up we'll see if he agrees.
Last edited by turtlevette; Apr 21, 2007 at 01:24 PM.
Thread Starter
Burning Brakes
Joined: Mar 2005
Posts: 1,139
Likes: 0
From: Salina Kansas
OK, here are some pics, just got done painting/clearcoating it. Gona try to work on the swing out bar tomorrow. Again, don't kill me on the welds please
Last edited by CorvetteDave01; Apr 21, 2007 at 07:29 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Looks like you're doing fine. I just had a custom one built in my car so I could still use the soft top as well as it was made removable. I have swing out bars and it was made out of Chromemoly and was powdercoated.
You're getting it all done for a lot less than I did!!
Keep it up!
JIM
You're getting it all done for a lot less than I did!!
Keep it up!
JIM
Le Mans Master
Joined: Nov 2004
Posts: 6,434
Likes: 0
St. Jude Donor '07
it'd be cool if somone could do an analysis.
i'm drawing it out on paper right now.
I did my rear braces much different than i've seen you guys do them. Instead of running it straight back i put an angle on it. In addition, it attaches to the top of the hoop rather than 1/2 way up. This in my opinion creates some effective triangulation side to side and maybe some less effective triangulation front to rear.
If you envision force trying to bend one side of the frame after the kickup in the upwards direction, that force will create a vector on that rear support in turn pushing in several directions on the hoop. The other rear brace acts as a restraining arm. So if you envision force being in 3 directions:
1. pushing towards the front of the car.
2. pushing towards the side of the car.
3 pushing up on the hoop
I think this creates a stronger overall system providing perhaps some stiffening for the rear of the car.
The disadvantage is obvious. Some rear window obstruction. The inspector has not said anything for the past 2 years. If you think about how much window a vert has, i still think i have at least that much view.
When TT wakes up we'll see if he agrees.
i'm drawing it out on paper right now.
I did my rear braces much different than i've seen you guys do them. Instead of running it straight back i put an angle on it. In addition, it attaches to the top of the hoop rather than 1/2 way up. This in my opinion creates some effective triangulation side to side and maybe some less effective triangulation front to rear.
If you envision force trying to bend one side of the frame after the kickup in the upwards direction, that force will create a vector on that rear support in turn pushing in several directions on the hoop. The other rear brace acts as a restraining arm. So if you envision force being in 3 directions:
1. pushing towards the front of the car.
2. pushing towards the side of the car.
3 pushing up on the hoop
I think this creates a stronger overall system providing perhaps some stiffening for the rear of the car.
The disadvantage is obvious. Some rear window obstruction. The inspector has not said anything for the past 2 years. If you think about how much window a vert has, i still think i have at least that much view.
When TT wakes up we'll see if he agrees.
I'm thinking of door bars also. I'll probably end up with the swing outs.
I just finished mine up today. Couldn't say I noticed to much of a difference. Forgot the camera though.
Thread Starter
Burning Brakes
Joined: Mar 2005
Posts: 1,139
Likes: 0
From: Salina Kansas
I think we have about the same rear hoop Chris. I'm just doing the driver's side swing out, don't want to mess with the passenger side and don't need it down to 10.0, I believe.
Are you welding yours in or bolting, I'm still debating...
Are you welding yours in or bolting, I'm still debating...
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
with no other changes than the addition of an 8-point bar, the car (owned by the magazine editor, and driven by his wife ) became much-more competitive and won several races locally, so, from a competitive-standpoint, the passenger-side diagonal door-bar might-be worth it.
Le Mans Master
Joined: Nov 2004
Posts: 6,434
Likes: 0
St. Jude Donor '07
The swing out on only one side sounds like a good idea. Do they sell a kit for only one side though?
Thread Starter
Burning Brakes
Joined: Mar 2005
Posts: 1,139
Likes: 0
From: Salina Kansas
Just about got the swing out bar done today, forgot to get pics though. I wish I would have bolted in the standoff already, so it was removable. I am seriously thinking about making the main hoop bolt-in at this point, although it will take way longer to get it cut down further, fab up plates, nuts or tapped steel plates etc. Only thing I'm worried about is losing some rigidity, but I would think the bolted in cage has got to be just as rigid when bolted in tightly?
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
BTDT... If you're going to ever put slicks on a Vette with enough power to pull the front wheels, be certain to keep an eye on twist by stringing it up and plumb-bobbing your frame regularly. Should your start seeing any changes, it's either time to go full cage with tubes all the way to the front towers or retire the car from the strip before you seriously twist it to a point where you'll have to re-jig the chassis to get it square again. Once it gets tweaked past about 1" - 1 1/2" or so, the frame shop likely can't pull it out without potentially causing further damage.
Last edited by TheSkunkWorks; Apr 22, 2007 at 11:52 PM.
Melting Slicks
Joined: Jan 2006
Posts: 3,028
Likes: 2
From: North NJ
Just about got the swing out bar done today, forgot to get pics though. I wish I would have bolted in the standoff already, so it was removable. I am seriously thinking about making the main hoop bolt-in at this point, although it will take way longer to get it cut down further, fab up plates, nuts or tapped steel plates etc. Only thing I'm worried about is losing some rigidity, but I would think the bolted in cage has got to be just as rigid when bolted in tightly?
I've heard mentioned several times on here how bad the C3 frame is and will twist like a wet noodle. The spot welds on the frame are not very strong. Someone had a video of their car and when they hit the gas you could see the frame really twist. Don't remember if the car was on a dyno or on jackstands, but the camera had full view of the underside. It was a crazy sight.
I can personally tell you that when I had a rolling chasis without drivetrain I could lift one corner off the ground and the frame would bend in front of my eyes.
Norval and I beleive a few others have the removable cages bolted to standoffs. If you use the proper Grade 8 or 9 bolts and torque them down good it should be just as rigid if not more than if it were welded to the frame. I'd like to see some pics of a rollcage in a vert.
Dave, that looks great, keep up the good work
Le Mans Master
Joined: Nov 2004
Posts: 6,434
Likes: 0
St. Jude Donor '07
I was talking about when you launch the car with slicks at a drag track it doesn't twist like other cars. Thats what he was talking about. I've never seen a c3 twist at the drag track.
I welded some un-welded spots on the rear part after you take the tire off. I'll probably try and weld more though.
I welded some un-welded spots on the rear part after you take the tire off. I'll probably try and weld more though.
Last edited by Yellow73SB; Apr 23, 2007 at 02:57 PM.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
I was talking about when you launch the car with slicks at a drag track it doesn't twist like other cars. Thats what he was talking about. I've never seen a c3 twist at the drag track.
I welded some un-welded spots on the rear part after you take the tire off. I'll probably try and weld more though.
I welded some un-welded spots on the rear part after you take the tire off. I'll probably try and weld more though.
In addition to installing at least a 6-point, it would probably be a good idea to weld up every inch of the frame you can reach, and to do some triangulating in the area around the transmission mount (being it's so far between the front crossmember and the kickup). A good reference is Twin_Turbo's work in that area.
Not saying other systems aren't sound, but thought I'd share the "typical" cage cited by the factory for C3's that used to be in the Power Manual, since I finally figured out how...
Last edited by TheSkunkWorks; Apr 24, 2007 at 01:24 PM.