Homemade torsion bar.

The steel which is welded to the torsion bar is so thick there is not going to be an issue even for how tight you tighten the bolts. It is not going to hurt anything. The holes are smaller in that location and I had one of the bolts on mine break, but I also used bolts I just had laying around so that could have been the problem as well. Once it broke I could see that the bolt had some rust.

On the holes I used the welded brace has a smaller hole. I just drilled it out to match the hole in the beam and I have had no problem.
 
Clod_King:5976474 said:
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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.
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Looks nice do you have a picture of it installed?
 
Actually, no. I don't have a picture. I have to park with half the car on a curb and the other half off to shimmy underneath. And at that point there still isn't enough space for me to turn my head, so I never bothered to snap any pictures.
 
From what I remember while examining the bar on the b-spec cars has rod ends on the end of the bar. This just ties the two ends together, which prevents toe changes. It doesn't really increase the stiffness. It will a little, but I don't think it is as effective as just one of the torsion bars. Plus I haven't really seen any evidence that the 2 has issues with the rear toeing out under hard cornering with slicks so I prefer to not change something if it really isn't an issue.

The main reason I did my bar the way I did was because when using the inner holes there is a gap between where the bar mounts and the brackets which are welded to the beam where I mounted mine. In my head I see this gap as an area where the overall torsion bar will be softer. I don't know if it is an issue, but I would rather have a torsion bar mounted between the two strong mounting points. To put in normal sway bar terms I see mine as more of just a constant diameter sway bar. Using the inner holes is like having a 1" sway bar, but the area where it mounts to the chassis is only 1/2 an inch. The effective rate is lower.

I also remember seeing a guy on here who bought a lower strut bar from civic and mounted it in the torsion bar. It really doesn't do anything because it has rod ends on the ends. As the bar twists the rod ends just rotate.

I would be able to reference the threads but i am on a business trip in china so the internet is really slow.
 
Clod_King said:
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.
Click to expand...

It is fun to see people experiment on the chassis. We spent time working on different variants of the bar before we decided on the one we offer. I like seeing other peoples input and design ideas.

-Derrick
 
zps2004 said:
From what I remember while examining the bar on the b-spec cars has rod ends on the end of the bar. This just ties the two ends together, which prevents toe changes. It doesn't really increase the stiffness. It will a little, but I don't think it is as effective as just one of the torsion bars. Plus I haven't really seen any evidence that the 2 has issues with the rear toeing out under hard cornering with slicks so I prefer to not change something if it really isn't an issue.
Click to expand...

What it appears to do, is limit the travel of the beam, based on its mounting points. The amount can be tuned by putting the bar under more tension for less travel, or more slack for more of a stock feel. Guess in this case the BSpec bar is not really street-able and designed for the extreme force the Pirelli race slicks puts the on the race car. I don't like the idea of limiting travel when I hit a bump, causing the rear of the car to hop up. Plus I do a lot of canyon driving and those roads are not racetrack smooth. I'm going to shoot Tri Point an email and ask em exactly what the hell this bar is supposed to do.
 
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Just a guess here... Also, I don't remember exactly where the Tri-point bar mounted, but... Isn't the torsion bar a "c" shaped torsion spring? From wheel to wheel, isn't is shaped like this [ ? If so, those two end points would displace vertically away from one another when pressure is put into the torsion spring. When this happens, the ends would get further away from one another. The Tri-point bar seems to tie the two ends together. The more pressure pulling the two ends together, the stiffer the spring would act.

The Corksport bar seems to increase the stiffness of the torsion spring itself. The Tri-point bar seems to add some kind of linear pull resistance into the torsion spring (probably some other kind of spring type).

Like I said, I don't recall the specifics of the Tri-point bar, but I vaguely remember the pics. Does this sound like it could be how it works?
 
That would be true which is why I said it will effect the stiffness a little, but I don't know if it would act as stiff as just making the torsion bar stiffer. Plus as you mentioned, in roll one end will go up and the other will go down causing the distance to grow between them. Their bar holds this distance constant. Well the only way this can be geometrically done is of the rear end toes in.
 
zps2004 said:
That would be true which is why I said it will effect the stiffness a little, but I don't know if it would act as stiff as just making the torsion bar stiffer. Plus as you mentioned, in roll one end will go up and the other will go down causing the distance to grow between them. Their bar holds this distance constant. Well the only way this can be geometrically done is of the rear end toes in.
Click to expand...

It does seem as though the structure would have to flex somewhere... so toe in makes sense. I wonder if they chose this method because it allows the system to be adjustable (more or less tension between the end points) and decided that was worth the trade off?
 
I am thinking that they did it because depending on how tight the rod is in tension or in compression you can adjust the toe. So it does allow for changing the alignment in the rear for toe. I just see that for a street car it isn't completely necessary, but for a racecar I can see the benefit.

I mean I am sure that they all work well they are all just different takes. I have the one I made, CS has theirs, racing beat has theirs, and Tripoint has theirs. I just like how they are all different which allows for development and different ideas to be thrown around. I saw a thread about a WV golf which had an adjustable rear sway bar for a torsion beam suspension. I am debating on making one for my 2. I don't see much benefit on a stock suspension since it can only take so much and I think my bar is about perfect for the rest being stock, but I am waiting for some good coilovers to come out, or I will make my own koni setup. Then I will look more into rear bars.
 
I think that it is something to look into but I don't think of it as a concern. To me I think it is just a warm fuzzy. I will explain that more in a sec.

When I first made my bar ,1" 120 wall I believe it was, I used 8mm bolts if I remember correctly. These were bolts I just wound laying around. I have no idea of the quality. They were the largest that could fit through the holes that I wanted to use. I had the bar on the car for over a year before one of the bolts broke while pulling into my apartment complex. There was some rust involved when I looked at the broken half. Where I mounted mine the two sheets of steel I bolted it to have 2 different sizes. The smaller hole I could only fit the 8mm bolt through. I could have replaced the bolt with a high quality one, but I just decided to drill out the smaller hole so I could use a 10mm bolt which is what I have in there now. The holes where the CS bar mounts are larger and I am guessing they are using 10mm bolts.

Now when it comes to the function of the unit as long as you have enough clamping force on the ends by the bolt there is no issue. There is no sheering force on the bolts. They are only in tension which is where bolts are strong. As the ends twist in order for the end to move on the torsion beam they have to overcome the clamping force by the bolt. Even when I had 8mm bolts I never had an issue with it moving.

Now when it comes to the amount of twisting seen, the stock suspension is worse case. As you can see on the youtube video I posted of the rear suspension of my 2 before and after I put my bar in place I was getting the inside rear to lift off the ground. This means that there can be no more weight transfer from one side to the other in the rear. All of this weight transfer has to be taken up by the torsion beam and the springs. Once you put stiffer springs on it, the rear torsion bar isn't going to twist as much before lifting a wheel. This means that the highest loading on the beam we are adding will happen with the stock suspension. Even if we add slicks to the car as soon as the rear lifts there can't be any more twisting of the beam.

Now for the warm fuzzy. Basically I have helped a good friend of mine design a number of parts for different cars. We constantly talk about the warm fuzzy. I will basically design a part which functions just perfectly, but then he will mention adding a certain feature which doesn't really effect the function, but it makes it look like it would be better to the customer. We call this the warm fuzzy. If you look at the Steeda bar and either mine or the CS bar, yes I will agree that the ends of the steeda bar are more secure to the car, but it really isn't necessary. As long as my bar and the CS bar don't move or break then there functionally really isn't a difference between the Steeda and ours. I am sure some people will buy the Steeda bar because of the extra mounts which is fine. I just prefer to keep things simple.
 
The bolt holes I used (and I think the same ones CS uses) are 14mm.

That being said I just took my torsion bar off. There was a squeaking sound coming from the rear end of the car this morning. Which by the end of the night turned into (what I can describe as a) scrunchy sound... When I took the bar off, the sound disappeared. The bolts were not loose, but they were looser than when I installed it. And there were two flat spots that had developed in each end where the bar contacted the twist beam. That being said, I think the material I used (mild steel) resisted deformation during the initial tightening of the fasteners, but during use had ended up deforming causing the flat spots. Which in turn allowed enough space to allow movement causing the squeaky scrunchy sounds, and the "looser" bolts.

That being said, I am going to make a new torsion bar to mount up to the outer holes, which have a convenient flat spot surrounding each hole. I will drill them out to accept the 14mm bolts I have be ause I feel that they are a good sized bolt to carry the load. Also the flat spots will allow a more firm mounting point than the arched surface where my current torsion bar was mounted.
 
I send to remember looking into that as well. I checked and you would be able to fit up to 1.5" ends on the flat parts.
 
Clod_King:5983580 said:
The bolt holes I used (and I think the same ones CS uses) are 14mm.

That being said I just took my torsion bar off. There was a squeaking sound coming from the rear end of the car this morning. Which by the end of the night turned into (what I can describe as a) scrunchy sound... When I took the bar off, the sound disappeared. The bolts were not loose, but they were looser than when I installed it. And there were two flat spots that had developed in each end where the bar contacted the twist beam. That being said, I think the material I used (mild steel) resisted deformation during the initial tightening of the fasteners, but during use had ended up deforming causing the flat spots. Which in turn allowed enough space to allow movement causing the squeaky scrunchy sounds, and the "looser" bolts.

That being said, I am going to make a new torsion bar to mount up to the outer holes, which have a convenient flat spot surrounding each hole. I will drill them out to accept the 14mm bolts I have be ause I feel that they are a good sized bolt to carry the load. Also the flat spots will allow a more firm mounting point than the arched surface where my current torsion bar was mounted.
Click to expand...

So I bought my stainless solid bar today but awaiting your troubleshooting to assemble it. The outermost bolt holes have a flat mounting surface and seem more ridgid. I'm switching to stainless fasteners and lock nuts maybe washers and jam nuts.
 
Today, 03:32 AMzps2004
I send to remember looking into that as well. I checked and you would be able to fit up to 1.5" ends on the flat parts.
Click to expand...

Which is perfect because I made I bunch of blanks in that diameter!


The bolt holes I used (and I think the same ones CS uses) are 14mm.
Click to expand...


I lied here. Or more accurately, I miss-wrote. The holes are 15mm, and the bolts are 14mm.

And there might another couple of homemade projects on the way as well.
 
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