Will 221 pound weight reduction make a difference on a track??

[FixedWing]

You've forgotten that there are two vectors. One is the vector placing downward pressure on the tyres. But there is a second one for the centrifugal force. So if you reduce mass at the back, you are reducing both of these evenly. The problem is that tyre traction is not linear with weight. So as you reduce mass at the back of the car, the reduction in the centrifugal vector and the downward vector will be identical but in fact you will get more traction relative to that downward vector than before because the tyre is operating more efficiently.

Yes, you will have a third vector forward under braking and this will reduce the downward vector, but as the car's mass goes down, this vector will decrease and the relative lightening of the downward vector will also decrease. This should be linear (except that braking will be very slightly improved). So this alone won't change things.

Anyway, the net result is that lightening the back should reduce oversteer just as lightening the front of our nose heavy pigs tends to reduce understeer.

Stephen

[rmonckton]

Wow...

Thanks for that

interesting..

[FixedWing]

It is the fact that traction is not linear to weight that makes it worthwhile reducing the mass of the car on a road course.

The other more obvious reason is what everyone else is talking about -- the ability to accelerate the car faster if it has less mass. That's the one you can quantify easily ("100 lbs = 10 hp"). Acceleration is mostly power limited. All of the other directions (braking, cornering) are tyre traction limited.

Stephen

[Andrew C.]

[FixedWing]

[OldSkewS4]

you forgot that he's changing the F/R weight distribution of the car.

[FixedWing]

[FixedWing]

Did not.

Stephen

[EdyJun]

Front passenger seat = 38kg's = 83.78lbs

Back seat (base and back) = 25kg's = 55lbs

Spare tire and tool box = 28Kg's = 61lbs

[OldSkewS4]

decrease weight on rear of the car under braking = more oversteer.