Home made sway bar

K

Kerry Foote

Well-known member
Has anyone ever made their own sway bar? Bought a piece of mild steel round stock and heated and bent it to fit. If so, what procedure used and any problems incurred?
 
I've heard of people using 4130, I think that's what Dave Headley used when he made the ones for my MGB. Mine are not bent they just have arms welded to them. What ever you use it has to have some spring to it. I think a lot of them are mild steel that is heat treated.

Dean
 
I did 2X for a front and also a rear bar but it won't work with just any steel. I bought some tubular 4130 from Aircraft Spruce had it bent to my specs, then heat treated (see Carrol Smith book on specs....). More trouble and $$ that it's worth.

Just buy a splined bar and arms from Speedway or Coleman and others and modify the arms as needed. This way you can order a similar center section if you miss the mark after testing.
 
Mild steel is not hardenable enough (not enough carbon and other additives like chromium and molyebdenum (sp?) ) to work as a sway bar. Read about it in Carrol Smith.
 
Jay,

I've been trying to keep up with your posts!

Jay's right. 0.4 o/o carbon (XX40) is about minimum carbon required to harden steel (form martensite). Other alloy materials are generally used to control carbon grain size and form.

Heating any hardened steel above the final draw temperature (600 o F.-1350 o F.) will further reduce the hardness (soften). Heating any steel above the "transformation" (critical) temperatures (1350 o F.-1700 o F.) may result in a totally annealed state (depending how it's quenched), as the martensite will have been allowed to "transform". "Red hot" is in the "Transformation" range. Welding on heat treated steel will soften the area near the weld (above transformation temperature).

Must know actual alloy to heat treat properly (Different "transformation" and draw temperatures, and different quench medium). Leaf/torsion springs likely high carbon/low alloy (1085) or a high carbon Silicone-Manganese alloy (9260).

Again, Jay's right. I managed several tool shops and had access to heat treat and plating facilities. Making my own was a last resort, due to time and costs. I did it, but it was really a last resort.

I scrounged through many junk yards looking for sway bars with dimensions and characteristics near to my needs. Many options available.

RJS
 
First, Ron - Plz check your inbox for a couple of PM's that you haven't picked up. Is it still full?

I made my own bar a long time ago on my Bugeye by using an as-purchased heat treated bar and then had it bent while cold. I forget what I actually used but it would read like 4130 HT or something like that.
 
I love it when the old curmudgeon actually agrees with me. Only happens 1 time in 10 though.......... ;^(
 
I would make my own sway bar, if I felt like rebuiling the CAR after the bar had failed. It will usually fail when you are deep in a turn, all crossed up, and leaning heavily on the suspension.

Using the wrong material and wrong techniques can create a bar that may suddenly break, or slowly bend. It will do that while you try to identify why the handling is changing on you. And, you will typically, in your analysis of the problem, be chasing every suspect component except the sway bar.

Take the advice of R.J and Jay, and buy the 3 piece modular bars. They are easliy tunable, strong and consistent.

I hate dodging a spinning car in front of me when they have had a sway bar suddenly snap or fail....
 
Yes; O. K. to cold form hardened material if done slowly and only slightly. Maintain original radius, if you can determine it.

Also, O. K. to cut off ends of sway bar (may require grinding), slot vertically, and weld in 1/4" tab for heim joint. Not highly stressed area.

Hit the "bone" yards before it snows.

RJS
 
First, I'm in Florida where we race all year, sorry R.J. Second, the cold bending was recommended by a friend which put me off on the idea. Thanks for all the advice and the metallurgical class, (very informative). I will look into the Speedway set up. That sounds like the ticket. Thanks too all.
 
Kerry,

Leaf springs are arched AFTER heat treatment. Biggest issue is removing "Decarb" scale. Made my own bending fixture and radius gage for Bug-Eye offset springs.

If bending circular bar, use a mandrel with original radius. May have to fabricate. NO sharp bends.

RJS
 
Ron - Thank you for confirming that you can cold bend heat treated bar, but being a mechanical engineer I already knew that, which is why I recommended it. I also know that it works as I ran the bar that way for 17 years. I don't know why someone thought it would break or bend, but it won't do either.

Now, I currently run a three-piece bar which is what I would recommend if you can afford it. There are plenty of them available out there now so you should be able to find something that fits. When I made my own bar 35 years ago there weren't that many available.
 
Ron, I also made my own offset leaf springs way back when I really poor. I am running a 3/4 front bar now but I have it adjusted to the shortest arm hole. The car handles pretty well to me but with a 7/8s bar it would give me more adjustability. Will you be coming to Central Fl. this winter?
 
Yes - I will probably go to Sebring again. Hope to se you there. I had a couple of 7/8 inch bars that weren'tbeing used, , but I must have sold them.
 
No, no.........I think living in Toledo made him into a curmudgeon. Don, I forget....where do you live?
 
I guess you're right. Living in the Toledo area, the economic capital of America, is enough to make anyone a curmudgeon.
 
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