There is a lot of advice about seats and weight distribution.
The consensus seems to be that getting the weight distribution right makes a difference to the handling of the kart, however...
a) the driver does need to be consistent, it is no good claiming that a new seat made a couple of tenths difference if the driver normally varies by a couple of tenths from lap to lap anyway.
b) the driver does need to be able to sit still in the seat. There is no point in adjusting the seat to the nearest millimetre if the driver moves his body around by 120 mm at each corner.
A simple experiment is to sit the kart on four scales, put the driver in the kart and ask him to move just his head / neck to look at each scale in turn. The head is typically between 5 and 7kg, which may be 10 to 20% of a cadets bodyweight.
(It's one reason why it is suggested that corner weighing on a kart is less useful, since so many drivers heads move around. One gets better results by strengthening exercises for the neck)
Common faults in drivers is allowing the body to move from side to side (needs strong core muscles to hold it still) and /or trying to hold the body straight by bracing it through the arms on the steering wheel, another is coming forward in the seat under braking, sitting upright instead of back in the seat and wrestling the steering.
Another action that is debatable in value is fitting a flexible seat to the kart, then bracing it with extra seat stays "because everyone uses seat stays".
Broadly the 'recommended seat position' is designed to put the centre of gravity of a 'standard driver' in such a position that it results in a weight distribution of approximately 42% front/ 58% rear. Since the standard driver is short, skinny, light and long legged, you can see there is considerable scope for the driver to be mismatched to the recommended seat position.
Some people suggest that with a cadet the height of the centre of gravity is as important as the fore and aft distribution. You really do need the CofG to be above the axle, not below it, so if you are carrying lead it may not be a good idea to mount it as low as possible especially if you carry a lot of lead.
There are a lot of posts on the ways of measuring or calculating the weight distribution. It is worth knowing what seat movement is needed to alter the CG by 1%.
A cadet kart is 900mm wheelbase
A)if the kart with driver and lead weighs 103kg (the minimum) and the distribution is 42 (f):58(R) then the moment about the rear axle is 58/100 *103 *900
=53766 kgmm
B)if the distribution shifts 1% forward to 43:57 then the moment is 57/100*103*900 = 52839 kgmm
the difference between A) and B) is 927 kgmm
From various posts it seems an average weight for a cadet kart with fuel is 57kg so the driver and lead weigh 46kg.
therefore to move the distribution forward 1% requires you to move the seat 927/46 = 20mm.
So while you are experimenting it probably isn't worth shifting the seat less than 20mm. It's the same as moving 4.6 kg of lead 200mm (ie from the back of the seat to the front) or 1.5kg from the back of the seat to front of the kart (600mm).
And if someone recommends that moving 5mm makes all the difference (ie 0.25%) then try it with fuel/ lead before turning the seat into swiss cheese. (Fuel weighs 0.8kg per litre)
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Used Kart Seats by 'Benno1976a' (09 Jul 2014 @ 12:47)
