Roll Cage Design II - roof area and down bars

BlueCoyote

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Good post on the Toyota roll cage design question.
Also doing a cage on a Toyota
How do you connect the rear down bars to the main cage and still be able to use the rear widow glass? Can you make it so that the rear cage can be removeable (bolt the rear cage to some mount tabs at the main hoop) and still be SCORE legal?
Any and all ideas or pictures greatly appreciated.


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84 Toyota p/u Rokrawlr
86 4rnr
80 Toyota MDR Project
 

partybarge_pilot

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You can put a slight bend at the top of the bed bars and go in above the window. This is slightly less strong than a striaght shot but acceptable. Or, you could just go witha plexi rear window and notch around the tubing. These also don't break when your newly uncoverd rear tires start throwing rocks.
 

ntsqd

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You could also put a bushing up there. Bring struture thru the back of the cab above the window and flange it. Then cross bolt the down tubes to those. Urethane isn't required, could pierce the down tube with some .250" wall 1" to 1.25" OD DOM. Yea it's a hinge. Don't think it matters for a truck that isn't race only.

As to the rocks off of the rear tires, ever heard of trash cans ? Buy a pair of those heavy plastic cans from Home Depot and just use the side of the can. Unroll them some & wrap it over the top of the tire. Easiest way I know of to get some polyethylene sheet.

TS

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BlueCoyote

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Plan is to build this truck to SCORE stock mini rules. This means that that the inner bed sides and floor will have to stay intact. Do like the idea of Lexan rear windows as even with a full bed rocks still fly around. Would like to make the rear cage 'modular' to ease in removal.
As for the top flanges and hinge idea - is that considred legal under SCORE rules?. As for it being a hinge, I may consider adding a simular set of flangs at the base of the main hoop to triangleate the entire sturture. SInce the bed has to stay intact, I want to be able to remove the back half for bed replacement due to damage. Do not want to have to cut up tubes to do so.
Comments and suggestions...

Who are you calling Coyote ugly?
84 Toyota p/u Rokrawlr
86 4rnr
80 Toyota MDR Project
 

ntsqd

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No idea if it's legal or not. Used to be done quite a bit using urethane bushes. Don't see it done as much any more. The pic of the truck that was linked (in the other thread) shows something like this done at every point where the rear cage meets the frame rails. Don't think I'd do it with urethane unless it's a street driven truck.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

TDORSloppy

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Thom,

Why would you want to use bushings on a cage, to replace it when it gets weathered? To give the truck a little flex when landing off a jump? Plus every place you have a bushing you have another notch, grind, cut, weld to do. I just can't understand why its better than straight welding it or using a tube clamp.
 

ntsqd

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One school of thot is that by tying the cage to the frame with some sort of bushing that allows a little relative motion, the stock frame will live longer. If the stock frame flexes, but the cage stucture is more rigid, it won't necessarily re-inforce the stock frame. It could just be working to tear loose all of the welds holding it to the stock frame. If you go to the trouble of making the stock frame rails equally rigid as any of the other tubes, then you could likely weld the cage to the frame and not have an abnormal fatigue life. If the frame rails are not as rigid as any cage tube, then allowing some motion will increase the life span of the rails.
Then there is the idea that if you really bend the stock frame, replacing it is a matter of unbolting the whole cage structure rather than having to cut is all loose and then deal with tubes might now be just a little short of where they need to be.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

Tyson

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Coyote,
its super easy to put in the plexi glass rear window also. when a rock shattered my window I just kept the rubber seal put it over a piece of plexiglass cut it with a roto zip (yes it took quite some time getting the shape right) but then just put it in the seal and worked the seal back onto my truck. Now I also have down bars that come down through the rear window, for that I just used 1 3/4 hole saw and cut where I wanted it.

Now my question, anyone know off hand for 1400 or 1450 (MDR) if these 2 tubes have to be welded all the way around? I'm pretty sure its yes but I just couldn't seem to get the welder at that angle, maybe someone with a bit more talent could (So that I don't have to cut the roof off just for these 2 3/4 unwelded sections.

Thanks in advance.

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BlueCoyote

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Like ntsqd's idea on the removeable cage. SInce this is being built to Stock Mini rules and the steel bed floor and sides have to be there, want to be able to remove the entire bed for when it gets damaged. Do not want to have to cut the tubes. As for the urethan mounts, my 86 4runner has full rear cage mounted on bushing full cage since 87, and 200k miles later the bushings still look fine.

Like the Lexan rear window idea - may just have to go that route.

As for the tube welding - My plan is to cut some 3 to 4" diameter holes in the roof skin just above where the welds will be. Weld it up and then stick a large plug in the hole.

Who are you calling Coyote ugly?
84 Toyota p/u Rokrawlr
86 4rnr
80 Toyota MDR Project
 
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