Anti Roll Bar

[Graham K]

Can anybody suggest the best grade of steel for the manufacture of an anti roll bar for a single seater race car.

Thanks

[crogthomas]

Depends...

Who is making it?
How are they making it?
Do they have heat treating facilities?
How will it be mounted? Does it need a splined or threaded end?
What is more important to you, cost or light weight?
Does it have to fit in an existing mounting bracket?
What was wrong with the original bar?
How stiff do you need it to be?
What approximate dimensions does it need to be (is it full width like a saloon car, or tiny like a F1 car?)

[Graham K]

Formula Ford, full width, standard shape, no ends, not too stiff, making it myself because i dont have one.

[greenamex2]

I just get Faulkner Springs to make mine from a diagram. It was very reasonably priced, turned aroud quickly and I didn't have to do much.

I am sure they are either supply the naterial or the spec of the material if you really wanted to DIY.

[phoenix]

Speak to the people who are going to heat treat the anti roll bar and they will spec the material. You have to use high carbon steel for heat treating - From memory I think we use EN19

[kmsport]

4140 Harden and temper to 42-44 Rockwell C scale.

[phoenix]

I found my metal order: in the UK EN24 is the best material for solid anti-roll bars (not available as tube as far as I know)

[ss_collins]

Well doesn't it depend on what you want the ARB to do, we use a selection with a variety of materials, very much horses for courses. If I were you I'd look into adjustable ARB's so you can set it up.

[phoenix]

Originally Posted by ss_collins

Well doesn't it depend on what you want the ARB to do, we use a selection with a variety of materials, very much horses for courses. If I were you I'd look into adjustable ARB's so you can set it up.

So what materials do you use, Sam? Didn't know you had made anti roll bars for anything.

Most people want an anti roll bar to perform the same function, surely? To resist roll - and then return to the design shape after deflection. To achieve this you need a material that can be heat treated to the right degree so it has sufficient "springiness" and that will not fail (break) after repeated deflections.

As I said earlier, speak to the heat treament people (as I did) or a spring manufacturer and you will get the right material spec. But trying if you try to use low carbon steel tube (CFS3 cold drawn, for example) - either with or without heat treatment - and the result will be a bar that bends well enough but stays deformed.

[dtype38]

Originally Posted by phoenix

Most people want an anti roll bar to perform the same function, surely? To resist roll - and then return to the design shape after deflection. To achieve this you need a material that can be heat treated to the right degree so it has sufficient "springiness" and that will not fail (break) after repeated deflections.

With respect, that's a bit like saying that eveyone want's their suspension to keep their car off the ground, soak up the bumps, and not let the car roll.... just cos the function is the same doesn't mean there's only one way to do it

When you consider restrictions in space, suspension angle, amount of deflection, amount of leverage, position of pickup points, etc. ARBs can vary dramatically in design and layout.

In fact, they can be so hard to get your head round, you could be tempted to just throw them away like I did

[phoenix]

Originally Posted by ss_collins

Well doesn't it depend on what you want the ARB to do

I was responding to the above, mainly.

Any reputable designer would, I submit, agree that the material required for the job has to meet certain criteria - principally those I have mentioned.

However, if you are certain that what I have said is flawed in some way, please correct me.

[TEAM78]

I agree with everything said, but I feel the situation is being made over complicated for amatuar racers here, I make my ARB's out of EN9 and bend them either cold or a little gas (plain carbon steel basically), so long as the ARB doesnt get twisted such that the material goes beyond its yield point then the material is being worked in its linear region hence it will always spring back to its orginal location. This could be argued to be a bodge or inefficient design but at amatuar level its good enough,
Remember, having the race winning car finished and ready to race the day after the race is no good to anyone, plus the way I do it is very cheap and fast. Maybe not the best method but it gets the car out on track
hope this helps

[greenamex2]

Originally Posted by TEAM78

Remember, having the race winning car finished and ready to race the day after the race is no good to anyone, plus the way I do it is very cheap and fast. Maybe not the best method but it gets the car out on track
hope this helps

Agree. To finish first, first you have to finish, and before that you have to start!

[phoenix]

Originally Posted by Graham K

Can anybody suggest the best grade of steel for the manufacture of an anti roll bar for a single seater race car.

Thanks

The thread started as above - "What is the BEST grade of steel"

I was just trying to answer the question as asked...........

Just to note, though, that it only cost me £30 to get 4 bars heat treated and as I had to buy some steel of the right size anyway, the extra cost of the higher grade steel was marginal.

[ss_collins]

our materials are something I'm not disclosing, but on one chassis type we found that one metal worked great (weight and performance) on another very similar (though still different) chassis the same design wasn't up to it, so changed to a slightly different material and it does the job.

Its a complex issue, choosing a material before a design is a little the wrong way round I feel, there may be a better material for the job, and as I say have you looked at making it adjustable?

[Splatz the Cow]

Interesting discussion.
This is a design issue. A complete analysis of the current situation would tell you the requirments you have to meet, to get the optimum result. Graham K you may or may not, be the person able to carry out that analysis, but that is a more important step to undertake than this discussion here.

By following the normal design process, it will give you a range of possible options you can investigate. At that stage, things will become a lot clearer, and you'll be closer to an appropriate outcome.

So the answer to your question, is that: Before you ask, "what material?" first you need to ask, "what is my current situation?"

[Graham K]

This is all getting over complicated although i appreciate the input.
Somebody out there must know what a roll bar for a mid seventies F.Ford type of car needs to be made of, avoiding the complexeties of heat treatment if possible.

[ss_collins]

question at the top asks whats best, not what do I use (which is best for my car), my point is that differing designs have different material needs.

On a old FF, find someone who has got the same car and copy it for the simple solution but what is best is like most things on a racecar. A complex issue.

If racecars were simple I'd be unemployed!

[ss_collins]

If the car was constructed by a reputable chassis builder then it would almost certainly have had heat treated anti-roll bars.

yes I agree but heat treated from what - to what. I did a lot of materials selection and engineering at uni (one of the bits I was actually quite good at) and the choice and different properties of identical looking bits of steel is mind boggling. So a big brute of a car may use one grade and a diddy FF or even a FS car may use a completley different grade.

What I'm saying is work out what you want the ARB to do, and whether you raw metal has been heat treated before, and exactly what steel it is you are using.

There is no definitive 'best' material (most commonly used is not always best). So if you want a quick easy response copy someone else, theres nowt wrong with copying a functional design. If you want an optimal product, its time to get to the materials books and work it out. Me personally? being lazy I'd pick the copying option so I could get out there and play.

[phoenix]

It can be relatively easy to copy someone elses design - but without a sample of the material they are using it would be impossible to copy that aspect of the design.

Idiots guide:

If a steel is to be hardened and tempered it has to have a minimum carbon content between 0.3% and 0.5%, but the harder you want the end product the more carbon you need 'in hand' to start with. This puts 4130 out of the selection because the carbon can be as low as 0.27%.

4140 is in the range of 0.37% to 0.43% so is useable, but this is an american spec steel and therfore hard to come by and more expensive in the UK than the EN range of steels. EN19 is an chrome molybbdenum alloy equivalent to 4140 and so is useable for the kind of hardness required.

EN4 has a median of 0.3% carbon, which could be as low as 0.27% and the lower EN numbers (1 to 3, all suffixes) have less carbon than EN4. These are collectively known as mild steel or 'low carbon steels'

EN8 has so many suffixes that you could easily end up with a marginal 0.35% carbon.

EN9 on the other hand, with a median carbon content of 0.55%, is on the upper carbon limit for hardening and tempering and as it's carbon content could be as much as 0.58% it may well end up too brittle for an anti-roll bar, so not worth risking in my view.

EN24 is a high carbon, nickel, chrome, molybdenum steel alloy, very similar in composition to 4340. With a median carbon level of 0.4% and a range of 0.37% to 0.43%. Like EN19 this makes it an ideal steel for hardening and tempering.

Springs made from chrome vanadium or chrome silicon alloys. Alloys like these, together with EN19 and EN24 steels are known collectively as Alloy Direct Hardening Steels and are the only steels, to quote, "Suitable for applications where high strength and resistance to shock is important".

Knowing and using the right steel - or the steel that your opponents are using, won't make your car handle any better. But it will mean that your anti-roll bar will hold it's heat treatment and stay in shape throughout it's life.

The 0.4% carbon steels can be hardened to a maximum Rockwell "C" 44. At 46 they become too brittle, so not ideal for anti-roll bars.

38 is about the minimum hardness for anti roll bars. This will give a tensile strength in the order of 170000 psi minimum to 194000 psi maximum. Without heat treatment it could be as low as 70000 psi.

Hardening and tempering to anywhere in the range 38-44 will do the job, and any difference in the hardness will NOT affect the rate of the bar, so don't get too hung up on it unless you are really working lightweight bars VERY near their limits limits.

[dtype38]

Thank you for that Phoenix...

[phoenix]

I have just read that a certain Italian race team actually make there anti roll bars from a pasta/carbon composite, slow baked at 200 degrees c.

Don't tell anyone I told you, though.

[kmsport]

I already mentioned it before...fork type f/ford sway bar....
use 4140.......h&t to 42-44 rockwell c

[phoenix]

Originally Posted by kmsport

I already mentioned it before...fork type f/ford sway bar....
use 4140.......h&t to 42-44 rockwell c

Noted now and originally, but getting hold of 4140 in the UK is not easy.

[ss_collins]

carbon arbs do exist! no pics unfortunatley (not allowed to publish)