16mm diameter Thru Body Anti Roll Bars

[ix0ifan]

I have been trying to buy a couple of thru body 16mm ARBs for a while now and they are quite difficult to find.

I don't want to use non-standard after market parts so I am thinking of making a batch but to tool up so that they look correct will have a moderately high cost and I would need to sell a few extras.

I would think that we should be able to sell bars for between $160 to $175 each.

We would use a sensible grade os spring steel, upset forge and heat treat correctly.

If there is enough interest in these we could make the matching rear bars as well.

[jameshtaylor]

Why don't you just settle on 15mm front and rear, like the 73S, and forget about it? There is no practical difference between the two, and the 15's are a dime a dozen. My 15's actually measured about 15.5mm and my mechanic initially thought they were 16's!

[Flunder]

The 18mm through the body sway bar is in demand and supply is limited.

[j911brick]

I probably have a few sway bars I can part with, but I don't know the exact sizes, and i'm out of own right now. I think I have one from a '73T, and One from a '71S, and one from an SC, plus he rears from the same cars.

[68911+1]

Why don't you just settle on 15mm front and rear, like the 73S, and forget about it? There is no practical difference between the two, and the 15's are a dime a dozen. My 15's actually measured about 15.5mm and my mechanic initially thought they were 16's!

Clarification would be great on this. I don't have it in front of me but I recall that a 1mm increase in bar size results in like a 40% increase in effectiveness. Sorry that I can't point to a table or web page on this. I would like to know though.

Thanks

[MarkS]

This is an easy one, take a Weltmeister 19MM TTB and turn it to 16MM or whatever diameter you desire in a lathe, if you want larger than 19 start with a 22, it's high school shop 101. Factory end links fit perfectly with no modification. The WM is aprox 1/2" longer and that presents no problem but you can mill or file both ends 1/4" for exact factory length. Paint it black, no heat treating needed. If you really want to go the whole hog stamp the bar ends.

[j911brick]

Clarification would be great on this. I don't have it in front of me but I recall that a 1mm increase in bar size results in like a 40% increase in effectiveness. Sorry that I can't point to a table or web page on this. I would like to know though.

Thanks

Its also going to depend on the spring tension of the steel, length of the bar, and polar moment. The question is: can you really feel the difference? I think one would be pretty hard pressed to feel the difference between 15-16mm.

[ix0ifan]

There are several interesting points that need to be considered.

The Polar Moment of Inertia of a torsion bar is proportional to the 4th power or the diameter.

This means that a 16mm bar will be 30% stiffer than a 15mm bar. If you can't tell this difference in Roll Stiffness on a race car I would be very surprised.

The 15.5mm standard bar must include some paint thickness as the tolerance of steel wire would be better than this and it is only the effective diameter that is of concern.

The 19mm, 20mm and other bars are surely from an SC and will not mount through body.

The Weltmiester bars are not sufficiently original to keep FIA Scrutineers happy at European Race Tracks.

If the ARB is made of a suitable grade of Spring Steel than machining a relatively hard and by its nature spring steel will be very difficult and introduce residual stresses that would almost certainly cause fatigue failures unless the bar was heat treated.

Finally the tensile strength of the Steel used only affects the point at which it permanently deforms and its fatigue life.

The stiffness of a bar for a given diameter is virtually unaffected by alloy content or heat treatment as Young's Modulus (E) is very consistent over a wide range of alloy content.

I gather from the basic tone that no-one is interested in 16mm bars made to the original design so I will just make a few for our own use.

Thanks anyway.

[72targa]

What ix0ifan said!

[70SATMan]

I gather from the basic tone that no-one is interested in 16mm bars made to the original design so I will just make a few for our own use.

Thanks anyway.

Not entirely. I'd be up for a 16mm at that price range. I'd also be up for an 18mm too.