I was out practising last weekend and tried a few different front end setups. I tried different toe / camber etc....

An example of a particular setting i tried was 2mm toe out and 0 camber with the front torsion bar fixed. This aligned perfectly on both sides on the laser aligner.

I then decided to take out the front torsion bar out to see how it would handle on track. I did this while the laser aligner was still fixed to the kart. I noticed the settings i had just made went shooting all over the place, ie one side went negative camber and one side went way positive with different toe.

I realigned it with the torsion bar out and got it all squared up again at 2mm toe out and 0 camber. I then put the torsion bar back in while the laser aligner was still fixed to the kart to see what would happen. The settings went all over the place again. I loosened the torsion bar and tried to tighten it equally on both sides but the alignment would still go all over the place.

So basically, the front torsion bar puts unequal amounts of stress on each side of the chassis at the front. So when we make these mm x mm changes to the front end while the torsion bar is fixed, the settings on the laser aligner may appear to be accurate. But given the fact the chassis could be stiffer on one side while the torsion bar is fixed are the settings really accurate?

Really interesting observation.

I've never thought about that torsion bar in/out making a big difference to alignment, other than with it out on track you'll have more negative camber because you've made the front softer.

It must be the bars that connect the bar to the chassis that are ~1mm out so when you put in on they have to twist. I have no idea if that's a common occurrence or not.

The static settings are still accurate you just have to remember to re-do the alignment after taking the torsion bar out or putting it in. When you have the bar in you will have a bit of tension in some direction and probably opposite on either side.

You might also want to (if you can with your lasers) put the kart on flat ground and sit in the kart and see how the alignment changes, just keep the steering in the same settings (you can move it a bit to get back to the same toe on both sides). It's possible that it will already move towards more standard settings(if torsion bar put them off) because it'll be twisting back to normal... then you can account for this when setting the static on-the-stand settings.

imo front end toe/camber settings aren't super critical as long as you have them about there - caster and ackerman for example effect handling a lot more.