Errrr..... 'stability'?
Wide rear increases the resitance to the kart 'falling over' (compare narrow track of a bicycle to a car....) so it DOES make a kart more 'stable' in THAT way....... but a wide rear makes the rear MUCH more likely to produce OVERSTEER and thus LESS 'stable' in THAT way! As yu can see, 'Stability' is not a very useful word here!
One of the main 'influences' on tyres is the pressure DOWNWARDS onto the track. As that 'down-force' increases, the grip INCREASES. In most cases, it's the OUTSIDE tyre (in any corner) which produces the VAST majority of the grip. The narrower the kart, the MORE pressure is exerts on the OUTER wheel in a corner and thus it INCREASES the grip on that tyre. Test it for yourself.
* Place you finger on a table
* Hold a pencil at the futhest end while parellel to the table top,
* Press down onto your finger with the other end of the pencil.
*If you make the pencil as 'long' as possible, *it is NOT going to put much pressure on your 'trapped finger' and it won't hurt.
*Now hold the pencil MUCH further along (and thus near to the trapped finger).
* NOW press down with the same force...... You'll feel the difference!
You'll see the effect of a shorter 'lever'. It's EXACTLY the same when you narrow an axle.... You get more 'leverage' onto the tyre if the 'lever' is SHORTER!
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Reducing front grip CAN reduce the effect of oversteer...... however..... think about it and you'll see it's NOT the first solution you should try..... I can show this simply with a daft example.... You COULD reduce the front grip by spreading grease on the front tyres..... would THAT make him quicker......?
The effect of increasing rear-grip WILL increase the tendency to UNDERSTEER at the front. Because those two are linked, people often make the mistake of thinking that REDUCING one will, automatically INCREASE the other...... not in ALL cases.... such as applying grease to tyres it won't.... Nor in many OTHER ways reducing the front grip!.
So.... before you think about reducing the grip at one end to make it handle better... you SHOULD be trying to INCREASE the grip at the 'offending' end! If you have done EVERYTHING ELSE to increase the grip but STILL have serious oversteer..... you can then, as a VERY last resort, reduce the front end grip to get better balance.... at the cost of a brilliantly controlable front-end...!
So..... let's look at this LOGICALLY! Look at the CAUSES of your problem and THAT should show you the solution.
You have excess oversteer and you want to remove it.... Oversteer is when the rear-end does NOT have enough grip. You can increase the rear grip in many ways: you need to assess which is the cheapest and most effective solution from just SOME of the following:-
1) New rear tyres?
2) Correct Pressure?
3) Too wide rear axle?
4) Weight FAR too far foward? (move driver's seat to CORRECT position)
5) Bad driving technique (too jerky, too late braking)
6) Badly set-up brakes causing rear to break-away on entry
7) Too much Caster angle on the FRONT end?
8) And so on....
Of that lot.... I'd look closely at:-
1) Driving style
2) the tyres
3) weight distribution
4) axle too wide
....in that order. However, anyone would need to know the kart and driver quite well before deciding the right order!
Remember, the answer is ALWAYS to INCREASE the grip at BOTH ends..... not reduce the grip at ANY end..... unless there are ZERO options left!
Ian
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Overtsteer on corner entry by 'PaulD75' (18 Apr 2011 @ 10:11)
