Author Topic: Roll cage main hoop design question.  (Read 5178 times)

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Offline Boostedballs

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Roll cage main hoop design question.
« on: April 10, 2014, 03:43:16 PM »
I have a Chevy Monza that I have been building and it's time to start bending the tubes. I understand that the cage has to attach to the body in a sandwich fashion but this is very difficult in the Monza. The issue is where the main hoop punches through the body. In order for this to work, I will have to bring in the mounting points of the bottom of the main hoop inboard to get to a flat spot on the floor. I won't be able to sandwich the body if I attach it to the rocker sill. Similar to the shape of the roll bars that attach to pickup beds. I know this weakens the loading from the top but what other options do I have?


« Last Edit: April 10, 2014, 05:44:09 PM by Boostedballs »

Offline javajoe79

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Re: Roll cage main hoop design question.
« Reply #1 on: April 12, 2014, 03:23:56 PM »
 On unibody cars you should build plates or boxes for the cage to land on. They should tie into as much area as possible. Just flat on the floor sin't always best unless their is significant structure under where you plan on landing the tubes. You may consider cutting out the floor and building a tubular structure instead then "hanging" the body from the cage/chassis
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Offline Glen

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Re: Roll cage main hoop design question.
« Reply #2 on: April 12, 2014, 03:44:52 PM »
BB, do you have a rule book????
Glen
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Offline Milwaukee Midget

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Re: Roll cage main hoop design question.
« Reply #3 on: April 12, 2014, 05:03:00 PM »
I was in the same boat.  The rule book kind of leads you down the path of a sandwich resolution, but reinforcing the perimeter gives you added stiffness all the way through, and distributes an impact over a wider area. 

Don't go with plates - they can still punch through the floor.

This was my solution - the idea being you want to build the car around the cage -



It ties into both the floor and the rocker panels.  There is additional work added after this was done, but this stiffened up the Midget CONSIDERABLY - which is a good thing for a car with a bolt-on fiberglass stop.

It passed tech last year.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline 1leg

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Re: Roll cage main hoop design question.
« Reply #4 on: April 13, 2014, 04:21:28 PM »
When i built my first drag car (78 TransAm) I added a subframe connector (3"x4" tubing) from the back frame structure to the front subframe. This was cut into and welded to the floor panels. The main hoop and front door bars were tied into this subframe connector by welding outrigger the same as the subframe connector into the floor using the same 3" x4" tubing. I also had added down tubes that were welded to the center tunnel and side panels using the sandwich method.

I'm not sure if this is the best method to use for Landspeed racing, and i never crashed the Transam so i have no real life test data. I'm interrested in seeing what other have to say on this.

If you have galvinized panels this can be dangerous!
Jerry
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Offline redhotracing

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Re: Roll cage main hoop design question.
« Reply #5 on: April 14, 2014, 07:48:15 AM »
We used through-floor SFC's to mount the cage instead
of relying on the sandwich... On our car (98 Camaro) it
was a lot easier in the end and added vital reinforcement.
Luke- Winston Salem, NC
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Ohio 2 Club- 203.712 (2013)

Offline toadjammer

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Re: Roll cage main hoop design question.
« Reply #6 on: April 14, 2014, 09:03:46 PM »
We used through-floor SFC's to mount the cage instead
of relying on the sandwich... On our car (98 Camaro) it
was a lot easier in the end and added vital reinforcement.
What are "SFC'S"?   _______ Frame Connectors?

Offline redhotracing

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Re: Roll cage main hoop design question.
« Reply #7 on: April 15, 2014, 07:51:55 AM »
Sorry- Sub Frame Connectors
Luke- Winston Salem, NC
Loring 2 Club- 201.252 (2010)
Ohio 2 Club- 203.712 (2013)

Offline Boostedballs

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Re: Roll cage main hoop design question.
« Reply #8 on: April 21, 2014, 08:11:40 PM »
Thanks for all of the input guys, but I'm abandoning the project to focus on building a LAKESTER!!  Hopefully I will be able to start a build diary soon.

Offline manta22

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Re: Roll cage main hoop design question.
« Reply #9 on: April 21, 2014, 09:34:32 PM »
"What are "SFC'S"?

Or, Sergeant First Class.  :-D

Regards, Neil  Page, AZ
Regards, Neil  Tucson, AZ

Offline Milwaukee Midget

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Re: Roll cage main hoop design question.
« Reply #10 on: April 21, 2014, 10:02:06 PM »
How far have you gotten on the Monza?  It's a pretty aero package that's easy to work on, and have generated some decent speeds over the years.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Boostedballs

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Re: Roll cage main hoop design question.
« Reply #11 on: April 23, 2014, 12:37:42 AM »
How far have you gotten on the Monza?  It's a pretty aero package that's easy to work on, and have generated some decent speeds over the years.

I've always liked the body style. I bought this car and drove it as my daily driver in 1997. It has since been powered by various small blocks and 4 different transmissions over the years. I had tons of free time when I decided to turn it into an LSR project a few years back. That quickly changed.

Here's what I've done so far:

The LT1 engine, exhaust, single Garrett T4 turbocharger system including intercooler and through-fender exhaust is complete. Twin wastegates, single blow off valve.
Front end upgraded to S-10 drop spindles, rear 3-link and ford 9" with discs are tack welded. Airbags in rear.
Interior gutted and cleaned. 5/16" plates welded to parts of the floor and rocker sills.

Needs:
Roll cage
fuel lines from twin in-tank pumps, regulator and filter.
Modify stock fuel rails for a/n fittings.
Need to install wire harness (already stripped to essentials)
Polycarbonate windows
Air dam
Brake/clutch/throttle assembly, brake lines are existing.
All safety gear
Parachute