Reducing Unsprung Weight

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09-13-2010, 06:41 AM

#21

Norm Peterson

6th Gear Member

Join Date: Feb 2007

Location: state of confusion

Posts: 7,635

Quote:

Originally Posted by Import_Slaya

Guys, great responses, but aren't we missing the point of the question? It seems like the responses are addressing rotational weight compared to static weight and the effect on acceleration.

Because that is where a significant rotational inertia term even shows up. Without that, you're simply comparing one static weight against another. I suppose that you could design such a short swing axle suspension that there would be significant rotational inertia about an axis other than the axle itself. But a car built that way would be such crap to drive that a few effective lbs from rotational inertia about a longitudinal axis would be the least of one's worries.

Otherwise, I agree, sprung vs unsprung is not the same as rotating vs nonrotating.

Quote:

I'd be more in the engineering types digging into the unsprung weight issue and the real impact on handling and grip dynamics. I noticed I had to tweak my shock settings when I upgraded to the Brembo brakes (along with heavier discs and 18" wheels...).

It's about damped vibrations. Critical damping is a SQRT function of both mass and stiffness. So if your unsprung weight at one corner goes from 100 lbs to 110 and you were happy with the damping before, it suggests about 5% more damping would be desired (I think specifically bump damping).

Separate from tuning transient handling by adjusting the front vs rear dampings, different percentages of critical damping are required for best ride vs best grip. Maybe "ranges of percentages" is better, since "optimum" does not appear to be a sharply defined point and "optimum" is probably tied to driver preference to some extent. I know there's a plot of this in RCVD. And I really need to read a little more of Dixon's Shock Absorbers book.

Norm

Last edited by Norm Peterson; 09-13-2010 at 06:51 AM.

09-13-2010, 07:20 AM

#22

Unleashedbeast

4th Gear Member

Join Date: Feb 2008

Location: Pensacola, Florida

Posts: 1,465

Quote:

Originally Posted by forensicsteve

The point to be made here is that instead of power being generated by the relative motion of conductors and fluxes, it is produced by the modial interaction of magneto reluctance and redirected surveillance.

For the racecar, we use a malleable logarithmic casing in such a way that the two spurving bearings can run a direct line with the panametric fan. So using fluorescent square motioning, in conjunction with the drawn reciprocation dingle-plates of the lighter rims, it greatly diminishes sinusoidal depleneration.

Good one Steve, it was good for a laugh. Kinda funny when someone uses big words for humor.