Unsprung Weight & Handling (split thread)

[duncanm]

Actually, the opposite is true:

https://www.tirerack.com/wheels/tech/techpage.jsp?techid=108

well -- most likely because the stock spring and damper rates were not adjusted with the change in unsprung weight.

The whole thing is a damped system. Spring, Mass, Resistance.

OEM's spend a fair bit of time making sure their combo matches for the optimum ride / price / performance .

 

[Rally]

OEM's spend a fair bit of time making sure their combo matches for the optimum ride / price / performance .

And Subaru have shown time and again they don't really know what to do. Take the SG. Had a good ride and handling compromise, with a well controlled ride and decent handling. Come the SH, and it was the opposite. Ride was wallowing like a boat in a storm, and handling suffered just as badly. Or the Gen 4 Liberty. Lovely, well balanced car, becomes a floating barge with the Gen 5. Or compare an MY99 WRX with an MY09 WRX. One is nippy and precise, the newer car is a bouncing barge. They may spend a lot of time working on it, but if their intentions are unsound, the results will be as well.

 

[Bigfoot]

Actually, the opposite is true:

https://www.tirerack.com/wheels/tech/techpage.jsp?techid=108

Where in that page does it say the opposite of what you highlighted?

The only thing close to that is the lower profile tyres used gave a slightly harsher ride.

If you were to have less unsprung weight and set the suspension accordingly, the car will ride and perform better.

 

[Red XS]

Plus Size Wheels and Tires Using Heavyweight Wheels

Our experience showed that the heavyweight wheel's reluctance to be moved as the vehicle rode over expansion joints, patches and potholes actually damped the impact harshness transmitted to the suspension, and forced the tires to absorb more of the jolt.

 

[Red XS]

I agree with this statement pinched of another forum
"It appears that lower unsprung mass (like lighter wheels) results in a less bumpy ride over poor roads. However, the downside is that it could increase the "fine vibrations" that you feel over some "relatively smooth surfaces" such as concrete roads or an asphalt road with gravels."
I think unsprung mass would change the ride, but I wouldn't say it makes things better or worse overall. I've done calculations with spring and damper set ups before and have not done much with unsprung mass, mostly velocity, surface and sprung mass. Minor changes in unsprung mass has too minor an effect in anything short of high end motor sport and I suspect most manufacturers would be of the same view.

 

[gregjet]

Unsprung weight will have un effect two separate but linked things.
First undamped component: the ratio of weight to unsprung weight determines how much the whole system ( ie car and suspension) is effected but the movement of the unsprung part. Tiny unsprung weight with large mass ( and correct springs) and the suspension will any impulse through the suspension will move mostly the suspension components ONLY. The heavier it gets the more the rest of the system will move with the suspension movement. ie the more road shock will be felt in the car.
Second. The shockabsorber has to dampen the upward and the downward movement the more mass the more it has to work. This is worst when the transient it high enough to bounce the wheel off the ground if undamped or drops into a hole ( ie where the ground falls away faster than the wheel can travel downwards, then hits the ground).
A good way to feel this is on mountain bikes where the unsprung mass is a substantial proportion of the whole (riderless system). You can really feel the difference with wheel weight change in the way the bike behaves on bumps.