It depends on the make/model/age of the chassis and the weight.
However, most karts go towards more toe-in when you add weight (i.e. when compared to the kart sitting there on the stand or on the track without you sitting in it). To see this effect, place your kart on the floor and look at the front 'geometry' of the kart. Now put a lot of your weight on the front bumper by STANDING on it! Then release your weight and re-apply it repeatedly. You will see the whole RANGE of changes (and this is a LARGE range of changes) that happen to the geometry as you add-subtract weight! It actually looks pretty damned SCAREY when you do it! You'll wonder how the thing manages to get round the track at ALL when you see ho MUCH it flexes!
There is little reason to think the kart goes to MORE toe-IN while accelerating on the straight. In fact, it's more likely to move towards toe-OUT while accelerating for the exact reverse reasons of it toeing-IN more when you ADD weight to it... because, effectively, you are REMOVING front-end weight while accelerating.
Finally, under braking (at the END of the straight)..... it's more likely to behave like you have put on 20 to 50 kilos as your weight will 'move forward' over the front wheels and thus you will toe-in even MORE! Oh, and if you have front brakes.... it gets even WORSE under braking!
The behaviour of the chassis while actually cornering hardly bears THINKING about and the toe-angle will fluctuate wildly for a MYRIAD of reasons.
However, don't worry too much about it!
What matters is that once you have set the 'toe' before the race, there's not much you can do about it other than KICKING the track rods to put bends in them (to increase toe OUT in a a wet race (for example)). Thus you only need to get the FEEL of what your kart does as you change the toe-angle in a testing day and selecting the setting which you feel suits you best for each race day/session. Then, drive the heats feeling if you need more toe-in or out aiming to have this PERFECT for the final it for the final.
As a rough rule of thumb, greater toe OUT makes the kart more sensitive to steering position. A LOT of toe-out will make the kart VERY sensitive to steering position. This might be EXACTLY what you need when you have understeer (e.g., in rain......hence KICKING the bars if it rains DURING a race!).
Setting toe FURTHER IN will makes the kart more 'stable', sort of 'less skittish' .
Having said ALL that, it really DOES depend on your make/model of chassis and thus there really ARE no 'rules' about the effects! Only a sense that more karts behave as I explain than don't.
Finally, watch a kart's stub axle, wheel alignment, chassis 'flex', steering angle, tyre deformation, etc., in the MIDDLE of a big corner. Then watch what it does when it hits a bump or a kerb. You'll see why 'all bets are off' about the toe-angle during the corners! It all looks like a wobbly JELLY when under changing loads!
Ian
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Toe in and Out - The Myths by 'RWR' (09 Jan 2009 @ 23:23)
