Author Topic: Smartest, Best, Easiest sequence for building cage.  (Read 5649 times)

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Offline SteveM

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Smartest, Best, Easiest sequence for building cage.
« on: February 07, 2012, 02:21:38 PM »
I'm getting ready to start bending tubes for the roll cage in my '84 Rampage, and I'm soliciting opinions.  I've been running the sequence of building the cage in my mind, but want to make sure that I don't "weld myself into a corner" and create a situation where building the cage is more difficult than necessary.

Here's what I'm thinking:
1: Bend the main hoop that will fit behind the driver's seat in the cab of the truck.  Leave 2 holes in the floor for the legs of the hoop to pass through the bottom of the floor.

2: Bend the A-pillar bars that will extend all the way to the main hoop.  Tack weld these bars to the main hoop.  Again, leave 2 holes in the floor at the location where the A pillar bars will intersect the floor.

3.  Weld in the bar for the top of the windshield.

4.  Weld in the diagonal braces across the inside of the roofline. 

5.  Weld in the diagonal braces and shoulder bars across the back of the cage and weld in the dash bar.

6.  Bend and weld in the supplemental "funny car" style cage around the driver's seat area.

7.   Drop the cage down through the holes in the floor to weld all the upper surfaces that cannot be reached with the cage in position.

8.   Raise the cage back up, weld in the angled door bars, door sill bars, and seat support bars.

9.  Weld in the "floor bars" that will follow the contour of the floorboards on the inside.  Weld in bars from the front strut mounts to the A-pillars. 

10. Slip 1/4" plate under the feet of the cage, weld the 1/4" plate to the 1/8" floor boards.

11.  Weld the cage to the 1/4" plates.

This sequence is only in my head so far, I haven't cut or welded any tubes.  Any and all suggestions are welcome, especially those that will save me headaches in the future.

Steve M.
1/2 of the Rampage Brothers

Offline Kiwi Paul

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #1 on: February 08, 2012, 12:56:03 AM »
Steve, I would put #10 before#8, that way you know there is room under the main hoop tubes for floor plates, and you can also cut or adjust the lengths of those legs (make sure they are a bit long ) to position the cage up high enough in the cab to give you enough height over the top of your Helmet. Be a good idea to mount your seat at this point, then you can check seating position and think about your door bar placement and window net, lateral head restraint, etc. Have you considered making a short leg under the floor at those main points that would join into your subframe/rocker area? That way you could sandwich the floor between two plates, one on top, one on bottom. Don`t forget, you do have to do a bailout with all your Driving Gear on.....don`t box yourself into a corner......Oh--and paint the whole top of the cage before you raise it up into the car for the last time! (Don`t ask me how I know this......)

Offline Rex Schimmer

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #2 on: February 08, 2012, 01:36:00 AM »
Steve,
You might consider making the top of the cage as a "U" shaped loop and then bringing up the A pillar bars to connect to it at the upper part of the door front. I did a cage for a small Honda 600 a couple of years ago, (can't find the pictures!!!) and by using the "halo" method I was able build most of the cage, rear loop, rear diagonals, cross bars and the upper U shaped halo bar by tacking them in place and then removing the completely tacked assembly, less the front A pillar bars out through the door opening and weld them on my bench. I then fitted the A pillar bars and drilled holes in the floor for them, tacked them in place with the cage in the car and dropped them through the holes and welded the top. I had not planned to be able to remove most of the cage for final welding but without the front A pillar post on the cage it was pretty easy to remove, I probably had it in and out of the car 10 times.  Once the A pillar tubes were added the cage was in the car for good.  Just a thought and I am sure you will have some challenges.

Rex
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Offline redhotracing

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #3 on: February 08, 2012, 07:42:58 AM »
The "halo" method is definitely easier in ways, but chassis builders I
know almost all agree on the strength advantage of individual A bars
run directly from main hoop to floor with a cross bar running from A
to A across the top of the windshield. When I cut out the 1.625" cage
to upgrade to 1.75", I went from a halo to separate A's, and it seems
to be a lot sturdier. Of course, bracing the A's with a lower knee bar,
tying them back by X'ing off your door bars, and gusseting properly,
etc. will add plenty of extra strength as well.
Luke- Winston Salem, NC
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Ohio 2 Club- 203.712 (2013)

Offline SteveM

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #4 on: February 08, 2012, 08:33:04 AM »
Good stuff there, guys.  I had been mentally running through the option of the Halo bar as opposed to the 1 piece A pillar / roof bars.  I can see how the halo bar would be easier to fab and weld.  I'm going to give plenty of consideration to that option.  This is the first cage I have ever built, so I'm trying to weigh the ease of fabrication into the equation.  Obviously, safety is the goal, but I also need to be able to build this thing in practical terms.

I suppose I could attempt the individual A bars first, and if I run into too much problem getting good fitment, I could cut them off at the roof line and "re-do" with a halo bar.  My main concern with the individual A bars is getting both sides bent the same, to have good symmetry from side to side.  What are the other difficulties with individual A-bar construction?   

Also a good suggestion to swap #10 and #8.  With respect to a short leg from the rocker to the subframe rail - I have a boxed in section at the front location, which runs under the floor from the rocker channel to the subframe rail.  Since this truck had plenty of rust, I have replaced the factory subframe rail with a length of 2-1/2" x 3/16" walled square tubing.  The boxed in section from the rocker to the subrame rail is 1/8" sheet, and will have 1/8" sheet at the floor as well, with 1/4" plate on top of the 1/8" sheet at the cage mounting point.

At the rear of the cage, however, there is no subframe rail, just formed sheet metal.  I am building a 1/8" thick system of support on the inside of the cab, tying together the inside rocker channel with the rear corner of the cab.  The 1/4" thick cage mounting pad will sit on top of this structure.

Steve.
1/2 of the Rampage Brothers

Offline wisdonm

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #5 on: February 08, 2012, 03:25:36 PM »
Ahhh. The old, it's too rusty for the street. Let's race it. Been there. Over and over,...
Stand on it....brakes only slow you down.

Has a checkered past.

Offline redhotracing

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #6 on: February 08, 2012, 05:08:22 PM »
What are the other difficulties with individual A-bar construction?   

Uniforming was the hardest for me. ( a relative novice ) My advice is to write down
the measurements while building #1, how many clicks on the bender, etc. to duplicate
#2. Did it with back bars, got them perfect side to side. Allow yourself plenty of room
to cut, notch, cut, notch, etc. Regardless of the bar you're making, take a conservative
amount of material (whether cutting, notching, etc.) off at a time. No worse feeling than
taking 1/8" too much off a bar you spent 2 hours getting "just perfect."

The halo is no joy making either. IMHO, after doing the individual bars, it's an easier
process. Following the roof line then the A pillar to the floor as one fluid piece can be
a thing of beauty.
Luke- Winston Salem, NC
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Offline Cajun Kid

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #7 on: February 08, 2012, 05:16:17 PM »
I agree with Luke (Red Hot Racing)  my Vicky was Halo style build.. but the Studebaker is a one piece A pillar down leg design, kick braced, knee bar and tubular gussets.

Much better in my opinion..

Good luck Steve

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Offline Peter Jack

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #8 on: February 08, 2012, 06:10:39 PM »
When I was doing the old stock cars I used to tack the cage all in place then saw off the roof. You have to make sure the chassis is supported properly so it stays in alignment. The cage is really easy to weld just about everywhere and the saw cuts are negligible so the roof lines right up afterwords. Even the glass will still all fit.

Just another method to think about.

Pete

Offline Tman

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #9 on: February 08, 2012, 10:41:33 PM »
When I was doing the old stock cars I used to tack the cage all in place then saw off the roof. You have to make sure the chassis is supported properly so it stays in alignment. The cage is really easy to weld just about everywhere and the saw cuts are negligible so the roof lines right up afterwords. Even the glass will still all fit.

Just another method to think about.

Pete

Yup, and you can sleeve the A pillars if you are worried about strength when it all goes back together. My pal Randy the chassisbuilder cut teh roof off a guys glass 34 coupe when he recently built teh cage. The way they wanted it fit left no room to work around the tubes. It is alleged this car will be on the salt..............who knows.

Offline superford317

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #10 on: February 09, 2012, 09:20:08 AM »
i prefer the 2 full length A pillar bars with the conecting tube between them also.
another thing i prefer, was at floor level just above the 1/4 floor plates, i would
 run tubing conecting the bottom of the A pillar bars with the base of the main hoop,
 just above the 1/4 plate also. welding the tube to the floor and the inner door sill where ever i could.
Constructing a 1000hp turbocharged bellytank

Offline Peter Jack

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #11 on: February 09, 2012, 02:06:33 PM »
Great call Superford317. On a unibody car that will make the cage pretty well as effective as if it was in a full frame vehicle. Tying in the base of the cage in that manner won't allow the cage to penetrate the floor to any great extent so the full height protection will be maintained.

Pete

Offline SteveM

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #12 on: February 09, 2012, 05:40:56 PM »
I'm definitely on-board with adding a bar just above the floor, to tie the A-pillar bar and the main hoop together.  I am also planning to reinforce the inner rocker sill with 1/8" sheet, and weld some short sections from this lower bar to the sill.

My main concern is "welding myself into a corner", where I need to get to something that will be very difficult to get to. 

Thanks,

Steve.
1/2 of the Rampage Brothers

Offline kiwi belly tank

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #13 on: February 12, 2012, 02:23:20 PM »
Steve, Many people tend to build the cage close to the inner body shape for what ever reason & thats what makes them tough to build. If it falls over, the thing is "effed" any way. You're looking to save the driver, not the shape of the car. Don't be affraid to get it away from the body so you can get to it & then tab out to the body to tie it all in. That'll stiffen the car up a bunch too.
  Sid.

Offline redhotracing

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Re: Smartest, Best, Easiest sequence for building cage.
« Reply #14 on: February 12, 2012, 03:31:26 PM »
You're looking to save the driver, not the shape of the car. Don't be afraid to get it away from the body so you can get to it & then tab out to the body to tie it all in. That'll stiffen the car up a bunch too.
  Sid.

Agreed. We actually allowed some room between the A bar and the pillar, to "tab" things together is a great idea.
We also added a rocker bar along the driver's floor between the hoop and A bar, then added bracing between that
bar and the door bar. Lots of added strength there.
Luke- Winston Salem, NC
Loring 2 Club- 201.252 (2010)
Ohio 2 Club- 203.712 (2013)