ts80

Whether it understeers or oversteers with more/less weight on the back entirely depends on what the driver does.

More weight in the rear = more understeer when accelerating on corner exit...BUUUUT...higher tendancy to snap oversteer while trail-braking into a corner.

Edit: It changes depending on what you do. That's why many manufacturers aim for a 50/50 weight distribution. Although 50/50 is not a perfect setup for all styles of driving, it's a good neutral area.

ans2k

if u really want to know, just look for a guy who has an ap2 and did an ap1 suspension conversion. the ap2 has a 51/49 weight split and the ap1 has the 50/50 split. just compare how the two will handle under the same suspension.

Andrew77

isn't it 49/51? since braking would put pressure on the front tires...

chiney_dolly

ok...
i dont understand how you can say that adding wait to the rear of a car will increase oversteer.

adding weight (no matter the amount) will plant the rear of the car more firmly to the road, decreasing OVERsteer and making the rear of the car stiffer.
making the rear of a car heavier and stiffer will result in more UNDERsteer, because the rear has more traction than the front, allowing the front to slide more than the rear.

i owned a Mr2 before my s2000, and the mr2s (with relitive power) dont have a excessive OVERsteering problem.
mid engine cars have a problem of what they call snap oversteer.
meaning you can pick up a MINOR slide, and do an abrupt correction, and when the weight of the car shift, the car will quickly oversteer or slide in the opposite direction.

thats why in handeling balance is the key.
you dont want to make either the rear of the car or the front of the car significanly stiffer or heavier, cause this will result in either understeer or oversteer.

yes to an extent the way a car looses traction (either understeering or oversteering) has to do with the driver, but it also has to do with the characteristics of the car as well.

(just a young ladies input )

Nate4635

I'll give this a shot...


I DO think that the question is really tough to have a definitive answer and the best way to figure any weight issues out is to......try it out and see what happens. Because weight can affect a cars balance in different ways in different situations.

I know the OP said this question was asked with no application in mind, but mentioned the exhaust (and the sub as a "what if" im guessing).

The problem is WHEN is this oversteer/understeer happening? Braking, acceleration, through a corner?

Regardless of the car's tendency, the driver has a lot of control in oversteer conditions with his/her right foot. I think weight might come into play - when grip is lost, how easy is it to get back? Lift a little? Lift a lot? Stay on the gas?

With 911's, you have a car that is balanced that way from the factory, so to say there is more weight in the rear isnt quite right. To say there is more weight in the rear relative to the front, then...sure. And it makes sense, that you would not want to lift in an oversteer condition in most RWD applications as you are taking grip thats already been lost away from the rear tires. It would also make more sense to me the more weight thats back there - the more momentum that rear has.. So in snap oversteer conditions, it happens so fast, and the weight is on the move, so getting grip back is a lot harder?

Either way, I think you will need a LOT of seat time in a stock S2k at the limit to notice the 30 lbs that is lost (which all of it is not directly at the rear anyway)...



I feel like I could answer that question many ways.... many of which would contradict eachother

krnmike

we aren't talking about any other cars. their setups are a different world compared to the s2000.

like i said it will tend to understeer more in general

krnmike

the s2000 may be 50/50 but the front and rear wheel rates are different.

braking would shift the weight forward and the rear shocks will decompress, but you still have the 100lb of weight pushing it down. it will not oversteer. i'm pretty sure by the time you come into a long corner to do 'trail braking', you will already have the aero of the car defining most of the car's characteristics.

ZDan

Speaking very generally and broadly:
Under steady state cornering, same setup, on the same tires, more weight in the rear will cause the car to tend more to OVERsteer. This is because of the nonlinear relationship between lateral grip and load on the tires. 10% more mass at the rear requires 10% more lateral grip at a given lateral acceleration, but the 10% more load at the rear gets you something LESS than 10% more lateral grip. More weight in the rear => general tendency is toward oversteer, not understeer.

krnmike

[quote name='ZDan' date='Jan 7 2009, 03:18 PM'] Speaking very generally and broadly:
Under steady state cornering, same setup, on the same tires, more weight in the rear will cause the car to tend more to OVERsteer.

ZDan

For simplicity, I am referring to steady state, neutral cornering, not accelerating, not decelerating.

From the original poster's question: "if you add weight to the rear of a completely stock s2000 will this add oversteer or lessen oversteer?"

The 10% is somewhat arbitrary.

The question is what will happen to cornering balance if you add weight to the rear of the car. I.e., what is the handling balance of an S2000 with, say, 150 lb. in the trunk vs. the same S2000 with an empty trunk. This is the question I'm addressing. Same car, same steady state neutral cornering, two different weight configurations.

This is a different question, actively moving weight.

These FWD track junkies are doing two things, only one of them will increase oversteer in general (i.e., for a front, rear, or awd car), the fatter rear sway bar. Removing as much weight as possible from the rear gives their wrong-wheel-drive cars better drive grip under acceleration.