Cage shimmy (1 Viewer)

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I have a Metal Tech cage in my 40. My swampers are great until I hit 50 to 65 mph where there is enough shimmy to cause the cage to oscillate side to side. The tires are balanced with tire beads and are not going to get any better. The side to side movement at the top of the A pillar is not quite a 1/4" and a little bit of hand pressure will lessen it. I am designing a new bikini top that I would like to roll around the outer edges of the cage. This would create an issue when the cage is moving side to side. I fear it will badly wear on the top fabric.

I am searching for options to stiffen the cage enough to to eliminate the shimmy without causing issues with frame/body flex when wheeling. My first though was to attach the dash cross bar to the dash, but that could lead to too much stress when the frame flexes. Instead I am wondering if a little triangulation might add just enough stiffness. I just don't have any experience in this area to know one way or the other. My thought is to add a tube on each side connecting the A pillar to the dash cross bar as seen in the picture. Do you guys think this would be enough? Worth it, not worth it? I could add it above the cross bar although that would impinge on vision a bit. I might be able to do it at the top bar, but again that impinges on the forward vision. I would do it if it would make a bigger difference though.

1995786


Thoughts?

Thanks
 
what does your overall bracing look like especially above your head and how is it connected to the frame
 
what does your overall bracing look like especially above your head and how is it connected to the frame
My question exactly. If you're not running any direct frame tie-ins and the cage is bolted only to the sheet metal floor, you're going to get quite a bit of movement just from the sheet metal floor moving around. Not to mention that your cage won't do much in the event of an actual impact or roll.

I've had the full MetalTech cage in my 40 since about 05' and I get very, very little movement at all. I have all the cross bars and hip guards on mine. I tied it into the frame with fairly standard poly bushings and DOM tube, a good source is DIY4X. Here's a link and this is one of only several options:
 
The cage is bolted through the floor to welded frame tie-ins. It matches this drawing minus the hip bars. As you can see the A pillar/hoop has no triangulation other than right at the B hoop.

1996136
 
Isn't your cage mounted solidly to the frame?
You should have it mounted cage plate/floor/frame plate welded solidly to frame.
Ross' description to mount is probably best if you want to limit squeaks and such, but metaltech recommends that you sandwich the body between the cage plates and solid mounted frame tie-ins.
I had zero movement in my cage when driving/wheeling (I also had all crossbars and hip bars in place, as well as metal metaltech's seat mounting option).
 
No broken welds. They are still strong and were done by a drag race shop. I knew better than to trust my own welds :).
 
It is sandwiched and welded to the frame as recommended by Metal Tech. I just sent them the same question. I'll post up any suggestions they have.

Isn't your cage mounted solidly to the frame?
You should have it mounted cage plate/floor/frame plate welded solidly to frame.
Ross' description to mount is probably best if you want to limit squeaks and such, but metaltech recommends that you sandwich the body between the cage plates and solid mounted frame tie-ins.
I had zero movement in my cage when driving/wheeling (I also had all crossbars and hip bars in place, as well as metal metaltech's seat mounting option).
 
Yeah, I've had mine installed both ways actually. Solidly clamped with the factory MetalTech mounts and then later on using the poly bushings in the link I posted. Movement is actually about the same which is very, very minimal.
 
other thing I see is lots of up and down and side to side but that will still allow some movement, there isn't any diagonal tie ins, I have always run a b pillar brace that goes diagonally from corner to corner
 
I know you said you love your swampers, but could this be the source of your woes. Before I bought my new tires, I had some second hand rollers. Windshield shimmy was horrible, I thought for sure I was going to brace the windshield to the cage. Low and behold, new tires and proper mounting fixed it. Oh and a new suspension and steering setup...
 
That will happen someday. I have my eye on some Maxxis tires. Anyone have $2k they can give me? Maybe a good sob story and a crowd funding site? Seriously though we are moving away from the purpose of my post. Triangulation. Is anyone familiar enough with cage design and fab to know if the short sections I mentioned would provide any stiffness? Maybe enough to dampen the slight movement I am getting?


I know you said you love your swampers, but could this be the source of your woes. Before I bought my new tires, I had some second hand rollers. Windshield shimmy was horrible, I thought for sure I was going to brace the windshield to the cage. Low and behold, new tires and proper mounting fixed it. Oh and a new suspension and steering setup...
 
So across the top bar to A pillar might be better than in the middle?

triangulating where you suggest will help, but the metal fatigue will move up the cage.... think of it this way, if you pressure in the middle of a bar, it bends far easier then if you put it at the ends....
 

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