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Trailing Arm Adjustment without VW Tool

September 24, 2010 | Troubleshooting & Repair

By Larry Coreth

[This article also available as an MS Word file with embedded Excel spreadsheet]

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 (below). 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" below 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 trailing arm vertically (see Fig.2 at right). 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:
    Sin∝ = (A-X)/C
    Where: ∝ = Trailing arm angle
    X = 77mm see Fig. 3
    C = 415mm effective Trailing arm length see Fig.2 (below)

    For those who don't, see the table at right.

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.

[This article also available as an MS Word file with embedded Excel spreadsheet]

4 Comments

Aa493c9f9299cdb0d51a6d201e2b655c 930
Lawrence Coreth
December 10, 2011 at 9:04 PM
The link to the Word file does not work !!<br />The Angle table is missing .
Img 0845
Nate Greene
January 19, 2013 at 2:05 AM
Larry,<br /><br />Going to try this in the morning. Am I correct the target angle I want is 20 deg.? 1965 c coupe.<br />Nate
Aa493c9f9299cdb0d51a6d201e2b655c 930
Lawrence Coreth
December 10, 2011 at 9:04 PM
The link to the Word file does not work !!<br />The Angle table is missing .
Img 0845
Nate Greene
January 19, 2013 at 2:05 AM
Larry,<br /><br />Going to try this in the morning. Am I correct the target angle I want is 20 deg.? 1965 c coupe.<br />Nate