Terms of the chassis measurement


Track alignment

Fahrachswinkel
Vorspur
MGF front axle MGF rear axle

The total track of a car axle is determined from the difference between the front and rear distance of the wheels of an axle, based on the wheel run flanges.

With modern wheel alignment indicators the track (toe angle) gets no longer measured in mm, but in angel minutes, thus the value no longer has to be referred to the rim diameter. (see formular written far below)

The single track marks the angle of an individual wheel - based on the rear axle - related to the vehicle longitudinal centre line, but at the front axle measured related to the geometrical driving axle.

Toe-in is indicated by a positive sign. A straight forward running wheel has the smallest tire wear. On travelling straight ahead are forces developed, which press the wheels outwards because of the elasticity in the front wheel suspension .

Therefore the wheels at the inner shoulder become prematurely rubbing. In order to work against this, one adjusts the wheels at none driven axles
(MGF front axle) to toe-in.

On driven axles the wheels are squeezed together additionally in front because of the driving power, Therefore the wheels are usually adjusted here to toe zero or even toe-out. The toe-in stabilizes thus the straight line discharge by spanning of the tire road-contact areas and prevents thereby a flutter and an erasing of the wheels. But take car Toe out can be very dangerous at the MGF. The car reacts dangerous in the wet !!!

If a vehicle at the rear axle has unequal single track values, than the front wheels need to be steered in right or left direction to travel straight ahead.
So that the bisector of the front axle total track is parallel to the bisector of the rear axle total track (= geometrical driving axle).
Thus the vehicle drives in the " Dackellauf ", and the steering wheel is on an slight turned steering location.

alignment at the MGF, Official values are crap/ New values approved by loads of guys from the BBS

front

toe- in

 

+008' ... +002' per wheel

+0°05' ... 0°10' Toe in

 

rear

toe-in

+004' ... +08' per wheel


+0°05' or +0°10' Toe in

degrees track conversion to metric values
Sample 0°05' is zero degrees and five minutes
The toe in of EACH wheel = sine(toe in angle in degrees) x rim dia in mm.
Sine of 5mins= 0.001454

15 inches = 15 x 25.4 =381mm

Therefore the toe in= 0.001454 x 381 = 0.5540
So for two wheels the total toe in =2 x 0.5540=1.108mm

For a 16 inch wheel the same formula gives 1.1818mm
(Thanks to Bruce for the formula)



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© D.K. rev. 29.09.01