Homemade torsion bar.

[Clod_King]

So I saw there was a thread about buying a cheap torsion bar for our cars, and decided to build one on my lunch break at work. It's really not that involved. Anyone with a bit of know how, and access to a drill press, and a welder can make one.

The specs are: 7/8" solid steel bar stock, and two pieces of 1 1/2" round bar cut to 1 1/8" thick.

You drill a hole at 15mm or 19/32" in the middle of each of the 1 1/2" diameter pieces. These holes will be your mounting points for the torsion bar.

Then weld in your piece of 7/8" bar.

The space between centers of your mounting points is 550mm.

It's that easy. I went one step further (because I have to tools available to me) to counter bore a recess of 7/8" in each 1 1/2" diameter piece of steel to accept the 7/8" round bar. I did this to be on the safe side should the welds break (for some strange reason) the bar will not be deposited on the street.

Really you could make the torsion bar out of any type of material be it tube, or aluminium, or whatever. The only thing that must stay consistant are the mounting hole sizes (15mm or 19/32") and the spacing between the holes (550mm on center).

 

[Clod_King]

I weighs about 4.5 lbs. Its a bit on the heavy side, so i think i may try to make one out of 1 1/4"-1 1/2" tubing as well (if we have a piece long enough in the scrap bin at work). Otherwise I may have to make up something a little different.... we'll see.

I was also throwing around the idea of making up some mounting plates that could accept multiple sizes of tubing and solid bar stock to just test out other setups with out making up whole units every time.

 

[rchrist364]

Interesting

 

[Racebrewer]

Nice work.

How's the handling with the bar?

John

 

[Clod_King]

I don't know yet... Hahaha. I have it tacked up, and I am giving it to my friend who is a licensed welder to finish it up. I could weld it, but I'll feel better this way.

We do trades like this often enough. I'll machine something for him, and welds stuff for me. Nice little system.

Once I get it back, I'm going to blast it, and paint it before I install it. I'm wondering how it will perform myself. I kinda took the nominal size from the CS unit, and dropped it 1/8" for the steel substitute. I am wondering if it will be a stiffer or softer setup then theirs.... I guess I could just look it up in charts.

 

[zps2004]

I made the bar that is on my car. I used 1" .180 wall. I am really happy with it. I wouldn't go any stiffer on a stock setup, because in transitions you can tell that the dampers just can't keep up. Overall I am quite happy with only that on it. I am mainly waiting for some good coilovers/dampers to show up.

I don't remember the length, but where did you mount yours to? I mounted mine to a different set of holes than CS did.

 

[Clod_King]

I haven't mounted mine yet. I am getting back from my welder friend hopefully today. But the measurements it took are for the inner-most holes. I saw a second set of holes a little further out. Are those the ones you used??

 

[zps2004]

Yup. Those outer holes go through two sets of steel so I used them to mount my bar to since they would be stronger. I also checked and I could mount a 1.5" bar there if I eventually wanted to.

 

[Clod_King]

Yeah, those were the ones I was thinking of. I was using scrap pieces of metal from work, and we don't haves many usable long pieces so i went with the other holes. Does the cork sport bar use the inner most holes? I may try to make another bar out of two different sizes of tubing and see how that works too. There is a piece of 1 1/4" tuning and a piece of 1" tuning that are two short to use on their own, but I was thinking of cutting the 1 1/4" pice in half and sliding the 1" pice inside in the middle. It would be a kind of progressive rate bar I guess. Or only the middle section would twist, but I guess I will find out! Hahaha.

The paint is currently drying on bar (my buddy epoxy coated it green to match the couple of 2s on my car) so I still have to wait to test it out.... Oh well. I'll start the next bar tomorrow...

 

[Ryno666]

Please post length dimensions pics etc I'm going to attempt this but out of stainless. Thanks.

 

[Clod_King]

All dimensions are listed in the first post. Those are the dimensions for the holes corksport uses. Pictures should be as well (but I think the are in a link format). The holes that zps2004 used are different dimensions. I don't have those dimensions though.

I installed my bar today. What a difference. Everything else I stock, but the. It felt way more planted in the back end. Really satisfied my bar. The best money I never had to spend for sure.

 

[skullsroad]

Bah! Now I want to do this. I'm saving for a BSpec rear bar from TriPoint but I'm still on stock suspension right now. If I only knew how to weld....

 

[Clod_King]

You could still just make the essential pieces and drop it off at a weld shop. Go to a smaller shop, and they will do it for really cheap. It would only take fifteen minutes to weld it up.

 

[zps2004]

From what I have seen on the b spec kit, that bar is mainly for toe changes, not for acting as a roll bar.

 

[eyeballs]

I really like the idea of using those outer holes...especially if there's more metal there to bolt into. Seems like it'd stiffen things up more than the corksport length bar. I don't know enough about suspension geometry to figure out the benefit of that tri-point bar vs the other options...I certainly prefer the simpler, lighter options if there's not a big difference, but I imagine there must be otherwise the bspec kit wouldn't use that design.

 

[Clod_King]

The outer holes use a smaller bolt I believe. And I don't know if I would use the outer-most holes anyways. There is more material, yes, but there is a gap between the two pieces of steel. It looks like it is a gusset/reinforcement brace and I don't know if I would add the extra stress there. Also, since there is a gap, the bolt running through all three parts (twist beam, gusset, and torsion bar) will constantly be trying to squish them together. Essentially the bolt will constantly be trying the rip the gusset from its welds, and plus the torsion bar amps up the pressure every so often as well.

I'm no engineer, but I'm guessing that's why corksport uses the inner-most holes, and racing beat uses a clamp system to get the longer length torsion bar. Otherwise I would assume CS and RB would be using those holes as well... I am no engineer, but it makes sense.

 

[eyeballs]

I hadn't actually gotten under and looked. Didn't realize there was a gap, and it does seem like that could potentially cause problems.

 

[Clod_King]

Again, I am no engineer, so who knows. There are other holes I kinda looked at. But I don't know how sturdy they would be. If I end up making a third bar, it is going to mounted using a different set of holes. I just gotta figure out which ones, hahaha.

 

[CorkSport]

Again, I am no engineer, so who knows. There are other holes I kinda looked at. But I don't know how sturdy they would be. If I end up making a third bar, it is going to mounted using a different set of holes. I just gotta figure out which ones, hahaha.

You could also drill out the existing ones or make a new set of holes.

-Derrick

 

[Clod_King]

Im not too worried about that really. It's the gap between the two pieces of steel that I am more concerned with.

And I appologize for potentially stealing customers away. But as it so happens, I have birthday monies, and this little mod makes me want an SRI or your exhaust. I gotta pick first.