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Originally Posted by Suberman
The only discernible effect was, as I expected, a slight increase in polar moment towards the rear axle (I placed the sand at the back of the trunk (against the seatback) to minimize this. That way the weight is over the axle and not lifting the front axle at all.
The car was slightly trickier to reign in when stepping out.
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The "as I expected" betrays bias. People tend to experience (or *think* they experience) what they *expect*. Blind A/B/A testing would be better, but of course not hugely practical!
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The effect on forward traction was precisely zero.
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"Precisely" implies you made *precise* measurements. Did you?
Weight over the drive wheels will help a bit, but even 100 lb. added only gives you 4% more drive grip, which you may or may not notice.
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This is unsurprising since the factory weight distribution with driver has to be close to 50/50 (unladen is 53/47 f/r, but you can't drive an empty car.)
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Weight distribution is nowhere near 50/50.
http://media.caranddriver.com/files/...e-napoleon.pdf (55.2/44.8 full tank, no driver). They claimed 53/47 for the car
with driver and passenger and a full tank, but as-tested weight distribution with fuel and driver is 54/46. That's not very good in snow... 100 lb. at the front of the trunk even with the rear wheels improves this to 52.2/47.8. Better, but not HUGELY so. 47.8/46 = 1.04x the grip. Might make the difference, might not.
May as well put the weight as far back in the trunk as possible. The car will still be more drive-traction limited than front grip limited. Might put another .5%-1% on the drive wheels.
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The "problem" is the Torsen diff is too tight.
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I don't think so. The torsen is "torque-sensing", in low-torque situations, lockup should be light.
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The only real trouble with this car on snow is lack of straight line grip. That just had to be the Torsen. Nothing else could affect only the straight line grip.
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In a straight line, the torsen is ensuring that you don't get a 1-wheel spin and that both wheels are contributing as much as they can before they both start to spin. It is HELPING. Of course when you do break traction, you spin both wheels and lose all lateral stability instead of only spinning one wheel and keeping some lateral stability. But for sure the torsen is close to maximizing the available drive grip.
The PROBLEM is poor static weight distribution. The best solution is good winter tires, which you already have. Putting weight in the trunk in the form of sand or kitty litter or other material that can also be used as traction-compound will also help. I did that with my old 240SX with similar weight distribution and no limited slip.
In my S2000, with Torsen diff, 49F/51R distribution with driver and fuel, on Dunlop WinterSport tires, never a prob
