THSCC Forums

I hosted it myself and added a few more outputs (angle relative to chassis and the track difference back to front). However I'll probably update it again. The semantics are screwy. The guy who wrote it uses the term 'thrust angle' as the angle between the car centerline and the parallel lines. However, with car alignments, thrust angle is the angle between the centerline of the chassis and the directionality of the rear tires (the rear total toe can be zero and the tires are still both heading in a non-straight direction):




http://www.jandlshort.com/pictures/jame ... index.html

_________________
2011/2012 Autox VP
2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B

Doesn't a+b = e+f imply that the front and rear track widths are the same?

[edit]

Nevermind, i see what you did there.

I'd love for this to work. If so then I'll be spray painting the positions for my jackstands into the garage and getting everything leveled. Thrust angle is the only thing left that I didn't know how to do easily enough to justify not paying for it.

Yep, creating e and f was the key to figuring out the proof....effective I made a new car that had equal front and rear track. Then used a little algebra to get rid of e and f and keep it only in terms of a, b, c, d and l

I updated the app at the link above and it calculates not only the toe angle relative to the chassis, but the total toe (f and r) AND the thrust angle. Enjoy!

_________________
2011/2012 Autox VP
2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B

Quick question:

For front- and allwheel-drive cars, should there also be a thrust angle for the front wheels?

_________________
Steve Carter
1972 Datsun 240Z-- resto pics at http://picasaweb.google.com/srcartermd
2007 GPW Honda S2000-- STR 86

Since those wheels steer, not really.

Say you use simple toe plates and get your front wheels to a total toe of 0 and yet relative to the chassis the driver wheel is 0.2 deg toe in and the passenger wheel is 0.2 deg toe out (again, this is zero total toe, but probably not what you were going for). You have a thrust angle per se, but those wheels turn so there will be a steering angle such that the thrust is zero such that the car goes straight ahead....however, you will no longer have 0 toe anymore.

So basically park the car with the steering wheel perfectly centered, pull the key, wiggle it to lock the steering and then do your alignment making sure to get your toe in, 0 toe or toe out relative to the chassis and even on each side (ie this method).

_________________
2011/2012 Autox VP
2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B

yeah and after you go through all that take it to Performance Chassis to get the camber and caster set and have the screwy toe adjustments checked, or follow Grahams advice before you do these calculations and just forget them.

_________________
2004 C5(415whp,390ft/lbs),
1997C5,1997Trans Am, 1986 C4,
1990 Miata, 1976 MGB,1997 Protege, 1989 MR2