Front and rear antiroll bar values?

I intend to re do the front and rear anti roll bars at some point and have started to play with two pretty easy calculators.

DAVES CAR MATH: Anti Roll Bar calculation and comparison

or

Tubular_vs_Solid_Anti-Roll Bar Excel Calculator - Suspension Design - File Catalog - BND TechSource

So if I have some ideas what value in pounds per square inch I was going for I would be much closer with my first try.

Are we talking less than 200-300 ft/lbs or more? If the car likes 200 front +- 25 and 150 rear +- 25 for example then all this is pretty easy. I just need some where to begin. Any ideas.

Basics = track car on Hoosiers

When I played with my sway bars I started by working out the rate of my existing bars and then decided from driving the car what % increase I wanted. Look at pictures of your car head on coming out of corners to see what amount of roll you have. Then I used these type of calculators to work out what bar specs were needed to acheive that % increase. Seemed to have worked quite well. Also make sure you go adjustable as that is really useful in changeable conditions and allows a little wriggle room in the maths. I would suggest you go for a range of 5 holes to give adjustment. If you have more then you can end up chasing your tail going for perfection. Some suggest 3 holes for dry , damp and wet settings as being enough. I was able to feel differences in between my different settings. I also took teh opportunity to make aluminium brackets with no bushing. Ie metal to metal contact. Need to get clearances right so it cannot seize, but that really helped for track work. I doubt you will hear any rattles if you have a decent engine in the back.

Fran, any starting values based on 01? I Just need some numbers to start with. If I knew the front and rear values on 01 I might be able to extrapolate a staring point based on spring rates.

I just don't want to build bars that are off by a 100% or more for the first go. Maybe the ones that are on the car are close but it looks like the rear is at least a 100% stiffer than the front.

Malcolm, thanks, I have a complete unknown at this point having not completed the car. I will more than likely just run it and see where I stand on balance but just on the face of it I don't think I will be close, so I have begun the process of learning how to do this. Hopefully I will make my own that come out close enough the first time so that the adjustment range is wide enough to tune it in. That's why if I had some values to start from it would be much easier. Thanks

Re: Front and rear anti roll bar values?

I tried to mirror the race car suspension and use 950lb springs up front and 1100 in the rear. The car felt pretty balanced as far as loose or tight. I would use bars that could be adjusted between 150lbs and around 300lbs with a change to a different hole. On my GT40 we did this and then added bar to the front until we had a clearly tight car. Then all the adjustments were made to the rear. Because my wheel rate was optimized with the springs, the bars started out equal front and rear. I made adjustments from there.

Hi Howard,

This chart was posted by Tom, to work out spring rates, and anti roll bar rates

View attachment SUSPENSIONCALCULATIONScoreccted.xls

Mick, Thanks, that's a good one.

Dean, 150-300 that's about what I was thinking. Good to have some data to confirm best guess engineering!!!!!!!!!!!!!!!