Front Axle Toe-In Curve, Adjusting
Front Axle Toe-In Curve, Adjusting
General
Toe-in curve
Notes:
Explanation of the term "toe-in curve":
- When the suspension is compressed (bumped) or extended (rebounded) the toe of the wheel changes relative to the amount of compression or extension. The resulting toe values can be plotted on a graph to obtain the toe-in curve.
- The shape of this curve is determined by toe value C1 (measured with the wheel in a defined starting position B1) and by toe value C2 measured at a rebound, or extension, of 40 mm or 1.57 inch (for heavy duty suspension 1BB) or of 60 mm or 2.36 inch (for all other suspensions) relative to starting position B1).
- The resulting change in toe-in, (C2 - C1) is defined as "toe constant S."
Sport suspension 1BE
A Spring compression
B Spring extension (rebound)
B1 Defined starting position (vehicle at curb weight)
On vehicles with sport suspension, suspension must be extended 20 mm (0.78 inch) to this position.
B2 Vehicle suspension extended 60 mm (2.36 inch) compared to position B1, Refer to Setting suspension to starting position B1 below
C Toe-in
C1 Toe-in measured in position B1
C2 Toe-in measured in position B2
D Toe-out
V Toe-in curve
S Toe constant, C2-C1
Notes: The toe-in curve must also be checked in the cases (in addition to those specified in table, Refer to Suspension Codes, Checking Requirements.
- If the vehicle has been in an accident or sustained damage to the suspension components and/or bodywork.
- If the vehicle does not maintain direction of travel over bumps and when braking or accelerating.
Standard suspension 1BA, special suspension (1BC) and heavy duty suspension 1BP
On vehicles with standard running gear, the toe-in measurement C1 is measured in the defined starting position (vehicle at curb weight) B1.
B2 Vehicle suspension extended 60 mm (2.36 inch) compared to position B1
C2 Toe-in measured in position B2
Heavy duty suspension 1BB (vehicle ride height 20 mm higher)
On vehicles with heavy duty suspension 1BB:
C1 Toe-in measured in position B1 (defined starting position).
C2 Toe-in measured in position B2
Setting suspension to starting position B1 on vehicles with standard suspension (1BA), special suspension (1BC) and heavy duty suspension (1BP)
Note: Depending on the type of wheel alignment equipment used, it may be necessary to raise the front of the vehicle in order to position the VAG1925 spacer. After lowering the vehicle again the suspension must be bounced.
- Insert VAG1925 spacer together with VAG1925/4 adapters and screw both threaded spindles out until they just rest against front subframe bolts (arrow).
Do not raise the vehicle using the above procedure
The vehicle is now in the defined starting position B1 (for vehicles with standard suspension (1BA), special suspension (1BC) and heavy duty suspension (1BP).
Setting suspension to starting position B1 on vehicles with sport suspension
Note: Depending on the type of wheel alignment equipment used, it may be necessary to raise the front of the vehicle in order to position the VAG1925 spacer. After lowering the vehicle again the suspension must be bounced.
- Insert VAG1925 spacer together with VAG1925/4 adapters and screw both threaded spindles out until they just rest against front subframe bolts (arrow).
Make sure vehicle is not raised using the above procedure
- Raise vehicle at front lifting points.
- Insert VAG1925/6 adapter onto VAG1925/4 adapter for spacer gauge.
- Lower vehicle onto adapters.
The vehicle is now in defined starting position B1 (for vehicles with sport suspension).
Bring vehicles with heavy duty suspension 1BB (vehicle ride height 20 mm higher) into defined starting position
Note: Depending on the type of wheel alignment equipment used, it may be necessary to raise the front of the vehicle in order to position the VAG1925 spacer. After lowering the vehicle again the suspension must be bounced.
- Insert VAG1925 spacer together with VAG1925/4 adapters and screw both threaded spindles out...
- ...until they just rest against front subframe bolts (arrow).
Make sure vehicle is not raised using the above procedure
- Vehicle with heavy duty suspension 1BB is now in defined starting position B1
Notes: For all suspension versions (1BA, 1BC, 1BE, 1BP and 1BB):
- The defined staffing position B1 is the position the springs must be in when using the wheel alignment program to check the actual toe-in setting C1 for each wheel. Setting C1 should match the specification + 10 ft. ± 30 ft. (rough preadjustment). If necessary, the toe-in must be corrected by adjusting the tie rod length.
- If the settings need to be corrected, this will be indicated by the wheel alignment program.
CAUTION:
- Make sure that the wheels do not loose contact with the turntables during the lifting operation.
- If wheels do loose contact, do not move the turntables. Otherwise incorrect measurements will result.
Extending the springs (standard, sport and heavy duty (1BP) suspensions
CAUTION:
- Make sure that the wheels do not lose contact with the turntables during the lifting operation.
- If wheels do lose contact, do not move the turntables. Otherwise incorrect measurements will result.
- Raise vehicle at front jacking points.
- Lift cylinders out of threaded spindles and secure in position using locking pins.
- Make sure locking pins (arrows) are correctly positioned.
- Lower vehicle down onto spacer gauge.
Vehicle is now in position B2 .
Extending the springs (heavy duty suspension (1BB)
CAUTION:
- Make sure that the wheels do not lose contact with the turntables during the lifting operation
- If wheels do lose contact, do not move the turntables. Otherwise incorrect measurements will result.
- Raise vehicle at front jacking points.
-Lift cylinders out of threaded spindles and secure in position using locking pins.
- Make sure locking pins (arrows) are correctly positioned.
- Remove VAG1925/6 adapter.
- Lower vehicle down onto spacer gauge.
Vehicle is now in position B2.
Note: The wheel alignment program determines the current right and left toe constant (actual values of C2-C1. The program checks whether the current toe constant (actual value) lies within the tolerance (control value) refer to vehicle alignment specifications .
- If toe constant actual value lies outside control value tolerance, adjust toe value constant within adjusting value tolerance.
Adjusting toe constant "S"
- Loosen nut-A-.
- Back out bolt -B- approx. 4 mm (1/8 inch).
- Push tie rod end downward onto stop.
- Turn in adjusting bolt -B- until exact specifications are achieved.
- Tighten nut -A- to 45 Nm (33 ft. lbs.) and check values.
- Tighten bolt -B- to 7 Nm (62 inch lbs.).
- Lower vehicle to defined starting position B1 .
- Screw threaded spindle down.
- On vehicles with standard suspension, bounce suspension several times.
Checking toe constant after adjusting
The alignment unit checks the toe constant again.
- If the second check shows that the values are within the check value tolerance, the setting is OK.
- If the values are outside the check value tolerance, the setting must be adjusted again in position B2.
- Position B2: + 60 mm (2.36 inch).