Trailing Arm Adjustment without VW Tool
In order to begin the car must be on jack stands at the rear or better yet at all four corners.
1.Remove rear shock, axle from trailing arm and support it out of the way.
2.Remove the torsion bar cover
3.Lay out base line with string, 1/8” dia. or smaller out of nylon so it will not stretch too much,
from A to B in Fig. 1. The string is tied around the cover mounting boss, the top right one, with the string on top of the boss and taped down at “B”, ½” bellow the center of the bumper bolt holes for “B’/”C”, or 11/16” above the bumper bolt centers for an “A” . Then pull tight.
4.In order to mark the center point of the axle on the trailing arm which is located in space, you must use some tape to define its position. Using a pair of calipers, metric or English measure the width of the slot where the axle fits. Divide this number by 2 gives you the radius of the semicircle at the left. Place some ¾” wide tape on the railing arm vertically, see Fig.3. On the tape draw a parallel line from the top of the slot by the amount calculated as the semicircle radius. Then along this line measure from the edge of the semicircle over the same amount and mark. There is the axle center, approximately give or take the toe-in adjustment.
5.Now measure perpendicularly from the base line string the distance to the axle center. Call this distance “A”.
6.Now we do the number crunching. For those who remember their Algebra and Trig the formula works out as Follows: For those who don’t :
Sin= (A-X)/C
Where: Trailing arm angle
A = measurement per # 5 above
X = 77mm see Fig. 3
C = 415mm effective Trailing arm length see Fig.2
The above will tell where the tailing arm is set now. To change the position pull the trailing arm off the torsion bar
if you can, usually the torsion bar comes out too. From
here it is trial and error until you get the trailing arm to the
angle desired by using the associated calculated distance
“A” .
The manual suggests an increase of ½ degree for the drivers side. Remember the trailing arm angle is not the
same as the camber angle ! It only determines the camber
angle at the static unladen condition.
Problems and /or questions ? E-mail me
Good luck,
Larry Coreth
Note this is an Excel table so if you double click on it you can manipulate to suit yourself, i.e. extend, change increments etc.
Fig. 1
356 B/C Chassis
From Factory shop Manual
.
Fig.2
Trailing Arm
Fig.3
Rear of Chassis