I havent had the stones to try this myself, but I was reading a tech article on sway bar stiffness versus diameter, and I got to thinking . Our torsion bar rear suspension is basically a sway bar and a swing arm all in one, and from what I can tell it was hollow, in theory if it could be filled with a structural foam, it should give us a nice stiff rear end, for about $40 and with a negligable weight increase. I might get bored this summer and give it a try. But if someone can beat me to the punch, go for it.

 

If it were hollow, you could do that, but It's U section. The foam wouldn't stay in, but get squeezed out as the beam twists.

 

fill it with structural foam will not work. When sway bar work they twist and not bend.

 

The stock sway bar is too small to be hollow.

 

Joseph, structual foam resists and deformation within an enclosed structure, And I was speaking of the torsion bar, not a solid sway bar, because I don't have one in the rear, however if rosswond is right and it is u shaped there would be nothing to hold the foam. I'll get back under there this weekend and poke around.

 

I saw photos the other day of someone who had apparently drilled through either end of the torsion beam and welded a metal rod inside the u-shape for extra stiffness from side to side. I don't think I would try that to save 100 bucks. I'd go with the progress anti-sway bar myself were I to get one. The rear stiffness is really good stock, anyway.

 

Yeah the stiffness is good stock, iwas just theorizing, I would think the bar would only work with a couple of bends in it, where is that aftermathet one?

 

I could only see the little nub on the side where the end of the bar stuck through about an inch. No idea how they kept it from banging on the inside of the torsion beam.

 

its at the ULTRA RACING WAREHOUSE

 

Where do you route the rear one?

 

 

^^How much?

 

Good solution, nice and simple building on what is already there.

 

That replicates the stock setup (for those who have one) but I agree that a bolt underneath one like the one Redrumm suggests is probably just as effective and a lot simpler to do.

If you had to have a stock looking setup for legal reasons or something the way to go would be to get a rear axle from a Sport. You'd pay big for that though.

 

On one of the JDM V-tec Club videos, TODA does a chassi build on one of there RSX's from the grond up, and the drill holes in certain places and fill it with the expanding foam, and then they added more pinch welds all around the door jams where its welded.

 

I've always wanted to completely seam weld all of the spot welds on a car. Perhaps when I get the FD my wife has promised me.

 

yes sir but i dont think that would help underneath? i remember them drilling holes on the door frame and other places around the body

 

Filling the door sills with builder's foam is an old trick for increasing the stiffness of the body at minimal cost.

In my car clubbing days, there was a guy there with an Rx2 rally car that did this.

There is probably less benefit these days, since a Fit is a lot stiffer than a Mazda Capella. It couldn't hurt though, provided you sealed up the holes again.

 

The fit is stiffer, except for one place. The rear end, personally I will take it for the cargo space, i've used my fit to bring home a storm door, and vinyl gutters. I'm not sure the foam would be easy to use in the chassis itself. But I'm considering a rear tower bar for autocrossing

 

Put in a tower bar you can remove. Then unbolt it when you need to carry stuff.