How to make anti roll bars???

[jjjj3981]

I have an old Alexis formula car that I bought that did not come with anti roll bars. So, I will need to make some and don't know what they should be made out of or what diameter. From pictures I can tell that the originals were either 1/2" or 5/8" in diameter. When looking at all anti roll bars on many different formula cars I see that some are hollow and some look completely solid and some have solid ends. The pillow blocks look to be about the same on all of the Alexis's cars I've looked at. Do the bars need to be heat treated? Maybe only if they are hollw? If they do need to be heat treated I might have a problem trying to find someone that can do that around here. Don't know of anyone at the moment. Any help would be appreciated!

[Neil_Roberts]

There is a ton of valuable direction on the manufacture of anti-roll bars in Carroll Smith's Engineer to Win. If you intend to make a race car part, please read all of that book first.

[Brian]

Typical solid bar anti-roll bars "should" be a heat treatable steel like 4130, bent, heat-treated, tempered to a suitable hardness. Not a single FFord out of England ever had that, nor did most US made cars probably up to the Swift... As long as you make the bar and then don't exceed the plastic deformation yield point (bend it so that it doesn't recover back) the spring rate of the bar will be the same as the heat-treated bar. The "springiness" of steel is about all the same (it's called "Young's modulus"). If you buy a steel rod of a material called "Stress-proof", it's a trade name, it will be cold-formable and will be very tough, almost as good as heat-treated steel and a lot better than bent mild steel. Here is a tip - I have made perfectly satisfactory anti roll bars for vintage cars by cold bending the bars using a 6' long piece of scrap tubing for leverage and the trailer hitch ball on my truck for the bending die. I have made tubular bars by filling them with sand and hot-bending them by hand.

Brian

[nomis]

we just finished making a new rear roll bar for this atlantic car
think the old bar had a blown exshaust over heating the material to the point of deflection, however this is how i got the car so i dont know the story
we built a new bar, clamps and links
1" OD with 1/16 wall chromemoly no heat treating and nichel plated afterward
the most important thing was getting the bend correct
it must be the correct machine, if you find someone who makes roll cages to the correct standart they will have the correct machine
that is a bend without any stretch so it has the 1" diameter all way round at the bend
easy !
i would say you should be looking at a 5/8"OD min
the important thing is how long are the returns on the bar, which is in effect the stiffness of the bar ???
the links were made from mild steel and threaded hardware and rod ends came from pegasus
see picture for detail

[provamo]

try contacting Danny Pyanowski here.......i remember helping him bend bars for his Macon in the seventies......that guy really knows how to set up (and drive!) FF's

[HayesCages]

We just use 4130 tubing from Aircraft Sruce, bend to shape and use them. I have bent a few out of cold rolled mild steel with good results but not normally since the 4130 is so inexpensive, comparatively, and lighter since it's hollow.
The hollow ones we've made are at least .065" wall thickness, although we're making some for a production car soon and are using .095" and .120" for 3/4" OD and 1.25" OD respectively but welding the end lever onto the tube rather then bending the arms from the base material.
Bending is done on the same machinme we use for cages but with smaller dies.
If you want to do it yourself do the Carrol Smith reading mentioned above and bend solid barr around the trailer hitch ball (good idea!) Neighbors love watching folks doing crazy things anyway..."What the hell's he doing bending steel around a trailer hitch???"

Another thought is you can usually find a spring fab. shop locally that will make the bars for you; supply the material, bend to your specs and heat treat. Makes it very simple.

[jjjj3981]

Thank you ALL very much for your help!!!