Anti-roll bar material

[Raceworks]

I have an anti-roll bar with an effective length of 9 inches made from 0.625 x 0.058 4130 heat treated to RC33-35. Does anyone know of a steel alloy, given the same OD will be 20 to 40 percent softer in torsion? Using a smaller tube diameter is not an option.

Thanks,
John

 

[JohnLear]

My understanding is that the steel from which the ARB is made (both material grade and treatment) is more or less irrelevent as far as torsional stiffness is concerned. The material should of course be a 'spring steel' appropriately heat treated, but this is a longevity issue rather than a stiffness issue.

Changing steel grade and / or temper will I think only change the elastic limit, not stiffness (at least not to any significant degree). I think you'll find that to decrease stiffness while maintaining OD, you'll need to reduce wall thickness (or increase the length of the torsional section of the ARB, or the lever arms?).

 

[GregLocock]

That's right. Other options - D blocks instead of bearings, flexible connections at the outboard ends, or bends in the straight section. The usual approach is the flexible arms, for a race car, as they are tuneable.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[CoryPad]

How about a non-steel alloy? Titanium has lower elastic modulus and can be alloyed and heat treated to have equal strength to 4130 @ 34 HRC.

 

[Raceworks]

Thanks all. The issue is that the original dimensions must not be altered. No titanium is allowed. Is there a steel alloy that would enable me to go thinner then 0.049.

John

 

[MikeHalloran]

An axial slot or two will loosen it up a lot... and make it a consumable. Titanium is a much better idea.





Mike Halloran
Pembroke Pines, FL, USA

 

[bvanhiel]

All steels have pretty much the same elastic modulus.

-b

 

[NormPeterson]

Tubular OE bars have wall thicknesses more like 15% of OD.

I think you need to do something with the arms to make them provide the requisite flexibility in bending. That does assume that you can build up your own bar from separate pieces.


Norm

 

[thundair]

Cut slots

Cheers

I don't know anything but the people that do.

 

[JohnLear]

If changing the dimensions of the ARB is not an option, and you simply must have less roll stiffness at that end of the car, then possibly the only (?) option might be using softer springs?

 

[Raceworks]

I want to thank all of you for your posts. I guess I'll figure out an alternate solution.

Best regards to all!
John