15 replies to this topic

[chedda_j]

I was looking at the kaka box sway bay. The nascar style solid sway bar and splined trailing arm combination, mounted to the frame rails. Its a wicked idea no doubt. Now what I was thinking "how can I replicate this for cheap"

Here is a photo of the nascar style bar.



The bar in the center is more or less the same thing as our tortion bars. How can I use the stock tortion bars to make a sway bar?

First of all, take the old tubes, cut off the splined ends. These are going to be the ends of my trailing arm linkages. The other end of the linkages, will be a spherical bearing mounted inside of a tube. I will then link the two pieces with a 3/16" piece of sheet steel.

Now take two tortion bars, cutting off one splined end of each. Machine the cut ends to a taper to accept weld. Weld the two bars together. Now machine the weld flat. I plan on welding a tube over top of the joint for added strength.

To mount it to the axle, I plan on using pillow blocks, which will mount to the axle via welded brackets.

The spherical end of the linkage will be mounted via bracket. This bracket will mount over the old frame rail, and will be welded on.

You can see below my idea. It shouldnt cost me much more than 50 dollars, and will be 100% custom and one of a kind. I can also change spring rates with different tortion bars.

[Doodson]

Really? weld two torsion bars together try contacting Speedway

http://www.1speedway.com/Swaybars.htm

[chedda_j]

You know for a lemons car it wouldnt be a bad idea. And yes Im well aware of the website, that's where i got the photo from the first post. I was just dreaming this up around midnight, it was never set in stone. And cost wise I would probably never purchase one of those setups, just too expensive. I would actually invest into upgrading the internal bar before that one. I think i will go with either the caravan or addco bar in the end with spherical links. I guess I'm just not into NASCAR enough to put their technology on my car.

[chedda_j]

What if i was to use the splined ends in the center, and use the cut ends with trailing arms welded on. I don't know if i was to just give up yet. It's to bad the tortion bars weren't about 6 " longer. Then i could just use a single one. what if i was use the entire tube, welded butt ends together. Hmm.

[chedda_j]

Aparently Im not the only one who has done this.

Welding Spring Steel

Noted in this discussion that welding spring steel isnt that difficult aslong you aneal the material and use tig or arc. But, what they recomend is rather than weld the two pieces together, is to use a mechanical joint. Which makes a whole lot of sense, if its a mechanical joint that interlocks, then there wont be any real way for it to fail. They recomend a lap joint, then weld the grooves, quickly. They also note that you could also make a larger lap joint, then drill and bolt the two pieces together. And at last, I could machine a hole in one end of the tortion bar, and stub on the other. Then drill staggerd holes, and plug weld them. Im not giving up just yet.

[gustav129]

I personally would rather have one solid piece torsion bar like my MM sway bar for my Mustang.


For some reason, I'm thinking that you would end up having some issue with actual spring rates. I'm not a mechanical engineer at all, but I would think that the spring rate would be different at any sort of separation in the spring steel.

Basically, you'd have a certain spring rate for the torsion bar, except where the weld and over lap joint was. So the torsion bar is designed to twist a certain amount, but it won't twist at all in the two or three inches of overlap you may weld up. I'm sure if you weld it up, it will have a higher spring rate at the welds than if I welded it up (I'd snap it off). So you end up with two "spring" sections that are connected together.

It's like a TTB 4WD system in the 80-96 Ford F-150, it's an independent front suspension, but they act upon the other side, because they are connected at the center diff to make an "X".

I think it's great that you are considering costs to try to possibly lower costs for the consumers, but items like this are ones that I would not go "cheap" on for my auto-x car. If it were to fail mid turn in an auto-x or track day, then I may be put into a situation where I'm putting more lateral g forces than my suspension can allow.

I'd hate to have this happen unexpectedly (but this driver is used to it, and won C Prepared Nats):



But I wouldn't see it as a problem for a street driven car.

EDIT: I just came across your "giving up thread" (I'm only on here every once in a while), and it not my intention to try to be "that guy"

[chedda_j]

Ya it was more or less a discussion. I can't sell my self on the idea. If the rod was about 6 " longer and the ends were the same I could have made it work without cutting the bar. I think I'm going to go with the addco bar. I've had a request to look at install kits for after market sways, so after I'm done the rear brakea I will be down.

[EuphoricBlue]

Depending on the stiffness you want, what about using a pickup torsion bar and longer arms? Pretty easy to find a pickup bar long enough that you wouldn't have to join it in the center.

You can cut it to the width you'd want, file a rectangle in each end, drill holes, make arms that have a rectangular opening and are about 1" wide at the bar, drill holes, bolt together.
The rectangle "Spline" acts as the load transfer from the arm to the bar, and the bolts keep the arms from popping off and take up minor play in the joint.

[chedda_j]

Depending on the stiffness you want, what about using a pickup torsion bar and longer arms? Pretty easy to find a pickup bar long enough that you wouldn't have to join it in the center.

You can cut it to the width you'd want, file a rectangle in each end, drill holes, make arms that have a rectangular opening and are about 1" wide at the bar, drill holes, bolt together.
The rectangle "Spline" acts as the load transfer from the arm to the bar, and the bolts keep the arms from popping off and take up minor play in the joint.

Thats actually something I had thought of. I was thinking of making the ends heavy duty rectangle tubing, then welding the connecting trailing arm to that square. Also to have a retaining bolt like you said on either end of the tortion bar. The only little issue would be to align the square.

Now would it be stupid, to cut the two stock bars, flip them around and do just like you said, cut squares on each end. The other splined end would meet in the middle. These would be joined together by the splined tubing, welded together. This way I could still use the stock bars. Just a thought. What do you think? I could now still clock the bars.

[anjin]

Bit to complicated for my likes. Heavy as well. Instead of using two torsion bars look at tube steel - you could size the tube diameter and wall thickness to get the rate you want. Then you are also free to design and size the rest to fit into the rear of the car.

Or look at the later model honda 14mm and 16mm rear antiroll bars. Easy to source. About the right width, easy to weld a plate to get an adjustable length arm, Only tricky bit is attaching to either the axle or the frame rails and missing the exhaust. I/m using a 14mm with no internal bar, and its close to right on the stock length setting. (31mm front tb, 20mm front bar, 600 lb rear springs, high speed track)

Based on experience I'd go for a lubricated bushing of some sort on the bar itself, because when they bind they spit you out into a very rapid spin when the binding ends.

[chedda_j]

It sounds to me like you have a tiny sway bar and really heavy springs. I don't know maybe thats why you can get away with it? The addco one I believe is 3/4" and from what I hear that's not even enough. That's nearly 4mm thicker than your bar and is to be used with the internal sway. The tortion bar set up is hardly complicated IMHO, although I would prefer it to be the one piece design.

I looked at about a dozen sites for tortion bars at the right length and for a used one i could get away with a tortion bar from a 90's pathfinder. They are about 30" long. I haven't measured it all up yet but if memory serves me right, it's right around 28" between frame rails. This also allows for the use of common oval track tortion bars on Sprint cup like cars, as almost all of them are 30" long. Keeping that in mind you can get a 30" sway for $115 shipped. They are available in sizes 7/8" - 1 1/4" with increments of .060" . Then i need the mounts which would be made by myself. Just thinking out loud here.

[cbstdscott]

Heavy test springs vs. stiff sway bar.

The springs need to keep the tires in contact with the road, sway bar keep the car's body from getting out of parallel with the ground.

Too much spring will make the tire the softest part of the suspension and cause deflection in the tire body.
Too little spring will make the tire leave the road surface.

Too little sway bar will allow body roll.
Too much sway bar... I am not certain I have ever encountered too much rear sway bar on these cars.

[chedda_j]

Words of wisdom from Father Pepper.

I agree that stiffer the better, I was just surprised he has such a small sway. The kaka has 400 lbs and a 32mm NASCAR sway I believe. He has 600 lbs springs, and a 16mm sway. Seems a little off.

[anjin]

I tried the 350 lb springs and much heavier bar, with a sliding pipe on tube type infinite adjustment, and just didn't find it worked well enough. That binding of the bushes was bad with the suspension loads coming from the bar rather than the springs, and a few instantaneous spins put me right off that set-up. Maybe with proper bearings to transfer load I could avoid the binding. But the weight to add all that control to the bar wasn't worth it compared to the weight of stiffer springs.

I basically have gone for the simplest and lightest option. I can dial in understeer or oversteer from the arm length on the 14mm bar. And I an now do the same with damper settings with the tien set-up, so with lots of adjustment I'm a happy camper now. Just have to play with camber now. Need more.

Oh - I don't autocross, I do track. Its a fast track - 90 to 100 kph corners taken at 1.2g plus if you are driving properly, reaching 160 and 190 kph in straights. Big braking zones down hills. So I don't need lots of rotation at slow speeds, just balance at high speeds.

But please keep working on a torsion bar set up - another two crx's in the shed, and I don't want tiens and 600lb springs on them.

[zakats]

It would be neat to be able to put some of the spare torsion bars to use that so many of us have laying around. I will say that I believe that a diy (just add torsion bar) setup would be best, sourcing tb's for resale would be a logistics mess and kill your profit margin if you sell at (what I'd consider) a reasonable price.

An easily reproduced sway bar set-up that allows more tuning is desirable here, I'd just like to see be a simple/light weight modification that can be done for ~$200