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Weight Bias and Handling

Branched off the Cool C3 thread.

Quote:

Originally Posted by enkeivette (Post 46124)

Putting a C5 trans in the back would make it more like 46/54.

That's actually closer to a race car ideal. It would help a lot with planting power as the weight is right over the drive axle.

Quote:

Originally Posted by Vettezuki (Post 46126)

That's actually closer to a race car ideal. It would help a lot with planting power as the weight is right over the drive axle.

More weight in the back can actually make the car more tail happy, overloading the rear tires in a turn.
The main reasons you want a more rearward center of gravity is you are giving the front wheels more leverage authority over the cars moment of inertia, i.e. the car wants to change direction easier.

And having a rearward center of gravity allows more equal tire loading under braking allowing more total braking force to be applied.

Quote:

Originally Posted by Vettezuki (Post 46126)

That's actually closer to a race car ideal. It would help a lot with planting power as the weight is right over the drive axle.

My C2 is 43/57 from the factory.:drink:

Quote:

Originally Posted by Ultraperio (Post 46132)

Your front tires have enough to do with sharing friction with both turning and braking.:boggled:

Quote:

Originally Posted by BRUTAL64 (Post 46145)

Your front tires have enough to do with sharing friction with both turning and braking.:boggled:

Giving the front tires more leverage authority allows a greater change in direction with less tire loading.

Shifting your center of gravity rearward allows the rear tires to account for a greater percentage of total braking force. Offloading the front tires.

Quote:

Originally Posted by Ultraperio (Post 46132)

Thank you for the additional wholesome goodness of rearward COG bias. I was going for the simple dumb answer of launch traction. :mullet:

2010 Viper ACR: 49.5/50.5.
2005 Corvette: 51/49

:leaving:

Sorry guys, I believe the makers of these front engine rear drive supercars over yall when it comes down to what's best for a front engine rear drive car.

Seems simple enough to me, more weight in the front, more load on the tires, more understeer. More weight on the back, more load on the rear tires, more of a tendency to oversteer.

Equal weight distribution, neutral steer. Front engine rear drive cars always have slight oversteer. Putting more weight in the back would... make it worse. :nuts:

Yes, Ferraris and Porsches have a rear weight bias, but they also have the engine and your fat ass back there. I'm surprised they don't have more of a rear bias.

Quote:

Originally Posted by enkeivette (Post 46152)

. . . Sorry guys, I believe the makers of these front engine rear drive supercars over yall when it comes down to what's best for a front engine rear drive car. . .

These are street cars home slice. I was talking about idealized race cars. Ultraperio described it in more detail. And here's still some more.

Quote:

Center of gravity forward or back

In steady-state cornering, because of the center of gravity, front-heavy cars tend to understeer and rear-heavy cars to oversteer, all other things being equal. The mid-engine design offers the ideal center of gravity.

When all four wheels and tires are of equal size, as is most often the case with passenger cars, a weight distribution close to "50/50" (i.e. the center of mass is mid-way between the front and rear axles) produces the preferred handling compromise.

The rearward weight bias preferred by sports and racing cars results from handling effects during the transition from straight-ahead to cornering. During corner entry the front tires, in addition to generating part of the lateral force required to accelerate the car's center of mass into the turn, also generate a torque about the car's vertical axis that starts the car rotating into the turn. However, the lateral force being generated by the rear tires is acting in the opposite torsional sense, trying to rotate the car out of the turn. For this reason, a car with "50/50" weight distribution will understeer on initial corner entry. To avoid this problem, sports and racing cars often have a more rearward weight distribution. In the case of pure racing cars, this is typically between "40/60" and "35/65." This gives the front tires an advantage in overcoming the car's moment of inertia (yaw angular inertia), thus reducing corner-entry understeer.

In short, if you need/want a car that will easily change direction, you want a rearward weight bias. You'll also tend to get oversteer in steady state cornering, but that's not the reason for the rearward bias.

Quote:

Originally Posted by Vettezuki (Post 46155)

These are street cars home slice. I was talking about idealized race cars. Ultraperio described it in more detail. And here's still some more.

In short, if you need/want a car that will easily change direction, you want a rearward weight bias. You'll also tend to get oversteer in steady state cornering, but that's not the reason for the rearward bias.

Your bold text says race cars and sports cars. Further, I don't see the difference. Still siding with Chrysler and GM on this one, sorry. :judge:

Quote:

Originally Posted by Ultraperio (Post 46147)

Thus allowing the front tire to use most of it friction capabilities for stopping and turning the vehicle.:)