Engineering a sway bar

[TwoJ's]

Stamping the ends is exactly what I was planning on doing. That is the way the factory mounting points are made and it seems that it will cut down production time and cost significantly. The rod ends will have washers where they connect to the bar. The end that connects to the control arm will be under double shear, and will have spacers for alignment purposes.

[mojorising]

Just a thought for "production" purposes you could crimp the ends of the tube together and drill a hole instead of manufacturing the insert and welding it in. Would save on heat treatment too. Are you putting safety washers on you rod ends? Usually a standard practice with single shear rod ends for misalignment purposes. Cool project, I hope your job opportunity works out.

[Wh33lhop]

I like this thread a lot. Keep the pictures coming.

And to the guy who asked if stock E30 sway bars are hollow: no.

[Dave-ger]

The reason that spring steel is used is because of the yield strength. 4130 has a yield of 52 ksi. I have done stress analysis in torsion and bending and 4130 meets requirements.

I see, interesting. I figure even with that, it would still have some give, but it took a torch to bend it, so perhaps it won't flex enough while on the car to not return to it's original shape on it's own. I'm excited to hear how well this works out, it really makes me want to start making my own sway bars.

[Danny]

Great work.

[george graves]

Cool stuff. The thought process of constantly thinking on how you can build not 10, but 10,000 of something is quite interesting on it's own. Well, it's it's own challenge. Keep it up!

[TwoJ's]

You are exactly right george. My professor has brought this same thing up to me. It is not critical to the project to have a feasible production method, but it is something that we are taught as it is very important in the real world.

Since I finished the manufacturing ahead of schedule, I have actually decided to address this issue. I've got two weeks before the end of the quarter which is the required completion date for all of the manufacturing processes. I have already bent another bar, so I will be devising a different way of making the attachment points.

[george graves]

Is the project only to build a one-off bar, or are you also working toward how to build multiple copies? I was surprised by the milling of the end piece. Seems that wasn't the most efficient way of doing it - that's all.

[TwoJ's]

The reason that spring steel is used is because of the yield strength. 4130 has a yield of 52 ksi. I have done stress analysis in torsion and bending and 4130 meets requirements.

[Dave-ger]

great job, i love this. This might have been covered before, but doesn't a sway bar have to be spring steel? I know you're using DOM, which is really good stuff, but I'm just a bit curious about the elasticity of your material.

[TwoJ's]

It's been a while since I've updated. Here is what I've done since last time I posted:

After making them, I decided that the original design for the bar ends was not good enough. I wanted a bit more material to slide in to the sway bar, and the part that the links would bolt to were too thick. Also, they were straight and needed to be at a 16 degree angle relative to the lever arm on the sway bar.

More 1" bar was obtained. I turned down 1.5" this time rather than the .5" that was done originally.



This part of the bar end won't carry a lot of load since the bar end will be welded in, so in order to keep the weight down I used a 1/2 drill and hollowed it.



It was then taken to the mill. Like last time I used a .5" end mill to cut the bar ends down to the appropriate size.





Here's what it looked like after the mill work was done:





Here you can see the new sway bar sans ends sitting on top of the factory sway bar. It's clear that a straight bar end won't suffice.





I originally planned to make these bends in the hydraulic press. I realized that I would have to make a fixture to do that, so i decided to do it in a vice.



The stock bar was used as a reference.



And the bending was done using extra material I had. I know, the shop aprons are fashionable.



Here you can see it after bending with the factory sway bar behind it for reference.



Here is my sway bar with the end inserted. You can't tell, but it is sitting on top of the factory sway bar. The ends line up well. You can also see a hole that I drilled in the bottom of the bar. The bar end will be plug welded there, and it will be welded around the edge as well.



The ends were tack welded on for test fitment:



I also got my rod ends in that will serve as adjustable links. I like the zinc plating, and I'll have all of the hardware as well as the bushing carriers plated to match.



Test fitment was successful so the ends were permanently TIG'd on to the bar.







The bar was then ready to be sand blasted.





I then packaged it up and it is now out for powder coating. One of my professors has a connection so I am getting the PC done for free. While this is nice, I was not able to choose the color. It's just going in a batch with a bunch of other parts so it will be black. I am working on another bar end design, and the second sway bar will be zinc plated rather than powder coated.


Also, this project has provided a cool opportunity for me. I got in contact with a guy named Art Morrison who owns Art Morrison Enterprises (http://artmorrison.com/homepage.html). They are a very popular company in the muscle car world for making improved chassis and suspensions. He liked what I was doing and is looking for another engineer. I had an interview with them on Friday and it went very well. Their head engineer is going to devise an engineering problem for me to work on so they can see how I perform. I am very excited about this opportunity.

[bejbis]

Thanks for the input, but did you read the thread? It is not seam welded, it is DOM as I stated earlier. And also, the bar was packed with sand, and round bar was welded in to each end to keep it compact and to provide leverage -- also stated earlier.

Well damn, I feel like an ass now. Carry on.

[325ix]

Are you going to heat treat the bar? The area's at which you are welding are going to anneal and have internal stresses still. It has to cool from 1550 °F at no faster than 50°F per hour until 900°. Then air cooled. Do you have a furnace to accommodate this control?

Very cool project!

I would agree on the proper cooling process, I'm not sure about your times and such but when I made a chisel in the shop at school we had to dip it in oil after the final tempering process

[TwoJ's]

Just a couple observations. It looks as if your using seam welded pipe. I think you may have a problem with this stuff in the application your going for. Ask for Drawn over mandrel pipe next time, it will have better properties.

It also looks as if you might be having a bit of trouble with your bending. Looks as if your flattening out the pipe at the bends a bit. A suggestion here if you cant get ahold of a proper bender, is to cut the pipe a little long, cap and end, fill it with sand as much as you can and weld up the other end. It will keep the pipe from getting flat in some of the tighter bends.

All in all tho, looks good. Keep it up.

Thanks for the input, but did you read the thread? It is not seam welded, it is DOM as I stated earlier. And also, the bar was packed with sand, and round bar was welded in to each end to keep it compact and to provide leverage -- also stated earlier.

[bejbis]

Just a couple observations. It looks as if your using seam welded pipe. I think you may have a problem with this stuff in the application your going for. Ask for Drawn over mandrel pipe next time, it will have better properties.

It also looks as if you might be having a bit of trouble with your bending. Looks as if your flattening out the pipe at the bends a bit. A suggestion here if you cant get ahold of a proper bender, is to cut the pipe a little long, cap and end, fill it with sand as much as you can and weld up the other end. It will keep the pipe from getting flat in some of the tighter bends.

All in all tho, looks good. Keep it up.