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what material are anti roll bars made from?
smart51 - 8/9/17 at 11:29 AM

I want to make an anti roll bar for my tin top. Rather than spending hours in scrap yards with a tape measure, I might just make one from scratch. Are they made from a special grade of steel, or will mild steel be good enough?

gingerprince - 8/9/17 at 11:42 AM

quote:
Originally posted by smart51
I want to make an anti roll bar for my tin top. Rather than spending hours in scrap yards with a tape measure, I might just make one from scratch. Are they made from a special grade of steel, or will mild steel be good enough?


Given the ARB has to twist a little along its length, I'd assume there are different specs/grades with different amounts of flex to suit the particular requirements of the application? If you just grab any old bar and make something that "fits", chances are it'll be too stiff or too flexible to fix the issue you're trying to address?

Ivan - 8/9/17 at 11:50 AM

Any steel as long as the twist doesn't make it exceed it's elastic limit - i.e. when twisted and twisting force is released it returns to the exact shape it was before twisting.

Sorry that's not very helpful but you can make one, twist it more than your car would and see if it returns, very roughly, the further you can twist it beyond what your car would with zero deformation the higher your safety factor and the longer the bar will last.

The maximum twist in your car is with the one wheel at full droop and one wheel at full bounce.

[Edited on 8/9/17 by Ivan]

907 - 8/9/17 at 12:22 PM

Spring steel.

scimjim - 8/9/17 at 04:25 PM

http://www.locostbuilders.co.uk/viewthread.php?tid=102651

nick205 - 8/9/17 at 05:16 PM

People fit larger diameter ARBs to tin tops to increase the "force".

Aside from that I'd suggest they're made from Spring steel to account for the torsional twist they repeatedly encounter.

SPYDER - 8/9/17 at 06:38 PM

Like I said in the thread linked to above anti roll bars are normally made from EN45.

froggy - 8/9/17 at 09:50 PM

I've made all mine from cds tube and as long as the ends are not above 70 deg they don't go beyond the limit for deforming . I pick an od size that's got a choice of wall thickness so I can just go up a size if it's not working : both my cars are front wheels engined around 800 kg and I'm using 3/4 od 14swg

snapper - 8/9/17 at 09:53 PM

They are made of the same type of steel as torsion bats and road springs
I.e. Spring steel
If they were not they would either permenantly take up the position from the first time force is applied or fateful over time and break.
I had one milled to half thickness, it took 2 milling bits, bloody hard stuff

Theshed - 9/9/17 at 08:23 AM

If you are a cheapskate like me you could start with a torsion bar from a morris minor. That will give you a suitable grade of steel. Mill flats on the end and make up some arms (or buy some) and there you go. I have just slung some of these out...sorry.

froggy - 9/9/17 at 01:27 PM

Thought I'd check my last one after a yrs use and as I thought it's no different now as it was when I made it . Jacking the car from the outer ball joint with a digital level I had 17deg angle across the top of the chassis before the other wheel lifted and with the bar fitted it dropped to 8 deg . Same now and I doubt it twists more than 10 deg and being tube is stiffer than a solid bar

907 - 9/9/17 at 01:44 PM

quote:
Originally posted by Theshed
If you are a cheapskate like me you could start with a torsion bar from a morris minor. That will give you a suitable grade of steel. Mill flats on the end and make up some arms (or buy some) and there you go. I have just slung some of these out...sorry.





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smart51 - 10/9/17 at 12:38 PM

Thanks everyone. I'm going to make the torsion bar from CDS tube. There's not going to be so much stress on it that it needs special spring steel. But as it will be undergoing quite a lot of stress, I'll avoid ERW which might fail along the HAZ along its length.