Question for Billy Shope: 3 link calculator

[vanillagorilla]

I'm toying with the idea of running an asymmetric 3-link like you've outlined on your site. I like the idea of it cancelling driveshaft torque and equal tire loading. Also due to packaging constraints it really makes sense to put one in my truck.

Anyway, my question is about the gear ratio value that's part of the calculator. How does that factor into everything? I see that the calculator doesn't take into account engine torque, or even trans gear ratios, both of which affect how much torque the driveshaft or pinion see's. Does it matter how much torque the driveshaft see's? Or is it more of a factor of the torque differential across the driveshaft and axles?

I ask because the truck in question is turbocharged and the torque at launch will vary greatly with how much boost I decide to leave with. I don't want to setup an asymmetric 3-link only to have everything go out the window if I decide to leave with more boost (torque).

[BillyShope]

When you look at the engine torque, you're looking at the wrong end of the driveshaft. The driveshaft torque determines the forward thrust at the rear tire patch. This thrust then determines the weight transfer. The axle ratio establishes the relationship between the forward thrust and the driveshaft torque. The percent antisquat determines how much of the weight transfer is carried through the suspension links. The ratio of front roll stiffness to rear roll stiffness determines how much of the driveshaft reaction torque is directed to the rear suspension, helping to cancel the effect of driveshaft torque. All of this provides the informaion needed for the link geometry.
http://www.racetec.cc/shope

[BillyShope]

When you look at the engine torque, you're looking at the wrong end of the driveshaft. The driveshaft torque determines the forward thrust at the rear tire patch. This thrust then determines the weight transfer. The axle ratio establishes the relationship between the forward thrust and the driveshaft torque. The percent antisquat determines how much of the weight transfer is carried through the suspension links. The ratio of front roll stiffness to rear roll stiffness determines how much of the driveshaft reaction torque is directed to the rear suspension, helping to cancel the effect of driveshaft torque. All of this provides the informaion needed for the link geometry. All of this is independent of driveshaft torque input. As far as the equations are concerned, torque input could be 1 foot-pound or a million foot-pounds. The rear tires are still equally loaded.
http://www.racetec.cc/shope

[vanillagorilla]

Thanks for clarifying for me. I'm still trying to wrap my head around all of this.