is there a good resource for alignment effects on race applications?
For instance on a front wheel drive vehicle the front wheels are going to want to toe-in on launch the hardest and some while going down the track. How do I know how much it toes in though?
And lets assume the car toes in .10 degrees per side .20 total toe, do I want the tires pointing closer to 0 toe during launch or during while passing down the track? If it's while passing down the track I would have to run less toe out which would result in more toe in on launch.
So if anyone of you know of a good article or book that discusses theory like this - and more! - please share!
In fact if you know of any GOOD informative books that have actually taught you a thing or two about engine/car performance and function - please share and give a reason/opinion.
Thanks!
Wheel alignment and drag racing
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Re: Wheel alignment and drag racing
Well I'm not a FWD expert, but sounds like the best first move would be reiforce the suspension to stay in the same angle on all conditions.
Otherwise it will be aways a compromise.
Otherwise it will be aways a compromise.
'71 Z28 street strip car
Pump gas All motor SBC 427
3308 lbs-29x10.5 Hoosiers
NEW BEST ET
1.38 60' / 4.05 330' / 6.32@111.25mph
https://www.youtube.com/watch?v=99p13UK ... ture=share
Pump gas All motor SBC 427
3308 lbs-29x10.5 Hoosiers
NEW BEST ET
1.38 60' / 4.05 330' / 6.32@111.25mph
https://www.youtube.com/watch?v=99p13UK ... ture=share
Re: Wheel alignment and drag racing
Your best move is to adjust your kingpin angle for zero kingpin offset so that there are no steering forces.
Re: Wheel alignment and drag racing
Presumably what's meant is the scrub radius - in front view, the distance between the center of the contact patch and the steering axis projected down to ground level. Most front-drive cars have a slightly negative scrub radius as originally equipped, which leads to a toe-out torque around the steering axis during acceleration.
BUT ... it's not that simple. Forward-pulling force on the lower A-arm tends to compress the front bushing and pull on the rear bushing (if that's how it is designed) and that will let the ball joint pull forward a little. Depending on how the A-arm is designed, the deflections might not be equal, which might move the ball joint in or out a little as the drive force tends to pull it forward. Now consider the angle of the steering tie rod. In top view, if the net effect is a parallelogram (between the tie rod and the effective direction that the A-arm wants to move) then the wheel stays straight. If the tie rod acts at a different angle from the way the lower arm wants to move, it could affect the steering. Very complicated ... ! ! !
And there's more. If the outer CV joint is not straight (and it never is - operating straight in line is bad for universal joints) then there is a component of drive torque affecting the stub shaft. If left and right are equal then the steering forces cancel but the forces are passing through the rubber control arm bushings ... If the halfshafts are unequal length (common with transverse engine) and not straight (see comment above) then the steering forces don't cancel, and presto, you have torque steer.
There is probably a way to figure out the proper relationship between scrub radius and CV joint angle to cancel this out but (A) I have no idea what that would be, and (B) it's going to change with suspension movement anyway, because that changes the CV joint angle.
I hate wrong wheel drive.
BUT ... it's not that simple. Forward-pulling force on the lower A-arm tends to compress the front bushing and pull on the rear bushing (if that's how it is designed) and that will let the ball joint pull forward a little. Depending on how the A-arm is designed, the deflections might not be equal, which might move the ball joint in or out a little as the drive force tends to pull it forward. Now consider the angle of the steering tie rod. In top view, if the net effect is a parallelogram (between the tie rod and the effective direction that the A-arm wants to move) then the wheel stays straight. If the tie rod acts at a different angle from the way the lower arm wants to move, it could affect the steering. Very complicated ... ! ! !
And there's more. If the outer CV joint is not straight (and it never is - operating straight in line is bad for universal joints) then there is a component of drive torque affecting the stub shaft. If left and right are equal then the steering forces cancel but the forces are passing through the rubber control arm bushings ... If the halfshafts are unequal length (common with transverse engine) and not straight (see comment above) then the steering forces don't cancel, and presto, you have torque steer.
There is probably a way to figure out the proper relationship between scrub radius and CV joint angle to cancel this out but (A) I have no idea what that would be, and (B) it's going to change with suspension movement anyway, because that changes the CV joint angle.
I hate wrong wheel drive.