Yes - Probably more than you want to know. (archive)

First, there are two types of torque steer. The first, which occurs in almost every front wheel drive is a tendancy for the front wheels to straighten if turned and power is applied. This is due to the amount of mechaical stuf that must be located in a very small area and the physical limitations of packaging compontns storng enough to withstand all of the driving and directional forces in a very small area. There are two geometric entities that affect how a car handles - the center of the contact patch of the tires and the axis around whch the suspenion systenm moves when the wheels are steered. Ideally, the steering axis should pass through the center of the contact patch. In FWD, the steering axis must also pass through the axis about which the constant velocity joint swivels. You also have to get a brake and ball joints within the center of the wheel. Generally a compromise results in the steering axis of an FWD car being imboard of the center of the contact patch. As a result there is a moment created between these two points. During acceleration on a smooth, level surface, the drive thrust tried to equalize the moments on each front wheel, and the car tries to straighten out. If you have uinequal traction, the wheel will saw back and forth, as the wheel with the greatest traction acts though the center patch to steering axis moment to steeer the car to the opposite side. The effect of the moment is magnified as offset thrust of one wheel gripping while the other is not tends to drive the car in the smae direction.

There are two ways to counteract this. One is to use a negative roll radius wheel. These are teh funny looking wheels with protruding hubs (used on the Olds Toronado and early VW front drive products). In these, the tire is moved inward so that the center of the tire patch is slightly inboard of the intersection of the steering axis with the road. "Sawing" during acceleration is damped as the moment is no reversed, and counteracts asymmetric thrust. the downside is that track width is lost and packaging is difficult. Either suspension travel (on parallelogram suspension) is lost or on McPherson struts, the strut has to be steeply inclined to miss the upper inner rim of the wheel - note that wheel width is also limited.

Audi has a new trick. rather than having a sibvgle ridgid upper A-arm, it is split into two struts. Each has a separate ball joint on the hub carrier. This creates a virtual steering axis, passing through the intersection of the projections of the two A-arms. The only downside is cost, as each side of the paralleleogram front suspension now has four ball joints rather than the usual two. I have this on my A4 quattro and it give much improved handling and steering feel.

There are two another torque steer problems unique to front-drive cars with transverse engines. typically, the engine is mounted on the right side of the chassis with the transaxle on the left. As a result of this configutration, the right halfshaft is usually much longer htan the left halfshaft. The first problem arises as, itf these were manufactured from iddentical materials, the longer right shaft would have a much greater torqe angle then the left for the application of an equal amout of torque. Step on the gas, and the car would veer immediately to the left then straighten. This is a fairly easy fix - change the Torque moment of the shafts to be equal. On VW products using trnasverse engines, the right halfshaft is usually a much larger diameter than the left and is hollow.

The second problem arises as a result of the CV joints needed (two per side). Torqe si needed to drive CV joints unless they are running with zero deflection. The torque required is a function of the angle between the driving and driven halves. The more they are deflected, the more energy they consume. As a result, under acceleration, drive shafts on either side of a FWD will tend to adjust themselves to equalize torque. As the shafts are of unequal length, the CV joints on either side would run with unequal deflections. The geometry involved usually causes transverse FWD cars to pull slightly to the left under acceleratione. One FWD manufacturer (whose identity escapes me) used a layshaft on the right side of their vehicle so that both halfshafts were of equal length and torque steer was minimized. My bet would be Cadillac on the Northstar equipped vehicles, as that much power from a transverse engine could be a real wheel-ripper, and a rude surprise to your typical Cadillac owner.

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