Physics Question: Thrust Angle

[RidingOnRailz]

Assume all things are equal: Same make, same year, same model car, all alignment specs and actual alignments as close to each other as possible.

The difference: One car's rear axle Thrust Angle is 1/2deg NEGATIVE(to the left) and the other's Thrust Angle is 1/2deg POSITIVE(to the right).

To which side will each car pull?

[maxwedge]

Based on my experience doing alignments, in practice, 1/2 degree would not cause a pull. But on paper a neg t'angle would cause a pull to the right, it would have to be more than 1/2 degree to do that.

[RidingOnRailz]

Originally Posted by maxwedge

Based on my experience doing alignments, in practice, 1/2 degree would not cause a pull. But on paper a neg t'angle would cause a pull to the right, it would have to be more than 1/2 degree to do that.

That confirms what I thought. Because the rear-end wants to go left it steers the front-end rightward. On my actual car the last TA reading I had was -.02deg. 1/50th of one degree! Pretty much arrow straight.

My Kia's steering wheel must be held slightly "negative"-to the left(learned that one from the NASCAR in-ride graphics during a race) when driving down the street to counter the effect of road crown. I consider that normal.

[maxwedge]

A 4 wheel alignmernt will get the wheel dead straight.

[RidingOnRailz]

Originally Posted by maxwedge

A 4 wheel alignmernt will get the wheel dead straight.

I recently had parts replaced and a 4-wheel performed. I'm not gonna cry over 1/50th of a degree(.02) of thrust angle. Better than the .18 I brought the car in with. LOL! I'm sure there's alot worse out there on the road right now.

One, maybe two degrees out on a lot of the vehicles around me, primarily because people abuse their rides and secondly because most wheel alignments performed are still front-wheel! Cheapskate car owners.

And for reasons I stated above I expect to have to apply a slight amount of left steering to counter the crown of the road I'm on. A mild drift to the right is acceptable - not a pull. BTW my steering wheel is straight when I let go.

[maxwedge]

All sounds well. LOL