Reliable way of testing anti roll bar

[newcomersnewbie]

Hi there!

Would anyone here care to give some thought on the alternative way of testing the anti-roll bar experimentally? I'm currently in need to verify some calculation i've made for formula student car. The idea is to test the bar without having to take them out from its mounting point on the car. Any thought would be greatly appreciated!

[Jersey Tom]

Why don't you want to take it off the car?

If you are hell bent on keeping the thing in the car, you can go get time on a SPMM (K&C rig) for about $10,000 a day.

Or... you can take the 5 minutes to pull the bar out, put it in a test fixture, and get your experimental data.

[flynfrog]

take off the dampers and springs replace them with a solid rod clamp the chassis down then lift a wheel with a know load. Use a dial indicator to measure deflection at bar. Do math

Profit

[Belatti]

I have never ever tested a bar outside the car. Motion ratios are always tricky to calculate afterwards, unless you have everything well measured and geometries simulated. Then:

1) Level the car in 4 bases, put the 4 scales and tare them to 0.
2) Replace the damper/spring of one side with a rigid rod
3) Take away the damper and spring from the other side (first of all remember to put something like a block of wood so the car will stay levelled after you take away the damper and spring ***).
4) Then you start adding gauges to the "free" wheel (I made them myself, from any piece of steel, 3,6,9,12,15,18 and 21 milimeters)
5) The difference in Kg. or Lbs. you see in the front scales for each gauge added is the force the bar applies to the wheel. You can repeat the test with different ARB cinfigurations.

*** ps: if the is very light and the bar very rigid, you will have to do as flynfrog said and clamp the levelled chassis to something.

[marcush.]

ah ..you need to do both.
who said your bar is working as intended when installed in the car?
so first you need to work out the stiffness of the bar in a fixture then measure installed stiffness...
and as a additional step what does it do dynamical..say kc rig..of course it may blow your budget out of proportion doing the last step..

edit:what does it help having measured the arb outside the car? it probably will not help you when setting up the car and changes do not translate to calculated stiffness increases and correlating handling changes..so what you really do need to know is what the bar really does in the car ,and what sort of changes your adjustments produce really.