>What you havent calculated for is dynamic weight transfer. AS the
accelrative force
>rises the weight and therefore traction of the front tyres decreases.
Pure RWD no doubt tends to some degree aid in that weight transfer. Mid
engined cars with *very* low CGs would have much less weight transfer than
street cars, implying that AWD might work better in such a vehicle.
>In purely
>straight line terms have you ever seen a 4wd drag car. The front tyres are
useless
Because drag cars are not trying to corner, they don't even need front
tires, skids would probably do. They are also purposely built with high cg's
to enhance weight transfer to the mega huge back tires.
>because they are lightly (or not at all) loaded. This is why low power
econoboxes can
>be FWD and no-one cares.
Not talking about FWD, I agree it is inferior in top level competetion,
although in street terms it is a bit closer.
>
>>
>> As to front wheel drive, I think most FWD cars suffer most from poor weight
>> distribution than the location of their driven wheels. My 82 Dodge Rampage
>> [FWD mini truck] was 80/20.
>
>They dont suffer fromn it. They HAVE to have it!. If it was statically
>balanced 50/50 then under dynamic load it could easily (with the high CG
>of road cars) get to 25/75 or worse and the wheelspin and lateral instability
>at the front would be lethal.
>
But they don't need 400 lbs of moter ahead of the front axle, creating huge
polar moments which, I was trying to say, are partially responsible for
their poor handling characteristics.
>This is really why it isnt useful in F1 anymore (if it wasnt illegal)
>tyre grip is high enough that even with a very low CG front tyre loads are
>small and available tractive effort is cetainly not worth the extra weight.
I will dare to say that you absolutely cannot, at the present level of tire
technology, efficiently put 800, 1000 or whatever they are running in F1
cars through an F1 size tire. Care to hazard a guess as to how fast they can
be going and still spin the tires? I'll guess it is high double digits at least.
>
>As a for instance a small Formula car has a download of 100kg per wheel
>at the front. Before the onset of aerodynamics the front wheel weights
>drop to about 50kg per tyre. The rears are up to about 220kg each. If you
>should happen to want to steer through the front there is obviously
>a very small amount of grip there to to share between lateral and (if
>it was AWD) tractive effort.
What I was getting at is that as you exit a corner, your cornering loads
drop, if you had the ability to put power to the front wheels, you could use
more of the available friction to accelerate onto the straight, without
wheelspin. Obviously if the front tires are saturated, they can't transfer
any torque. When you are out of the corner and accelerating in a straight
line in the range where a 2wd car could create wheelspin, if you could
transfer even 5 to 10 percent of the torque to the front wheels, wouldn't it
accelerate faster? This is why I think the Audis were so dominent until they
were also "ruled out"
>
>OK thats a racing car, the G forces are high compared to most road
>cars but the CG is very very low. The critical relationship is the height
of the CG
>compared the the wheelbase. If you have fwd and a high CG then you have to
put the
>weight forward.
So if you had a low CG and AWD ....
I will reiterate; if I can produce wheelspin or at least overload a tire in
both FWD and RWD cars in a certain situation that I face 3-4 times a day,
and can't do it in and AWD car, would it not follow that a race car would
also benefit?
Funny, rule makers don't usually rule out things that are a disadvantage.....
Keith
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