Alignment: Testing and Inspection
Test requirements:
^ Check suspension, wheel bearing, steering and steering linkage for excessive play and damage.
^ Tread depth difference of no more than 2 mm on an axle.
^ Tires inflated to correct pressure
^ Vehicle unloaded
Fuel tank must be full
Spare wheel and vehicle tools are stowed at correct installing locations
The fluid reservoir for the windshield/headlight washer system must be full.
^ Make sure that the sliding plates and turntables are not touching the end stop when checking the wheel alignment.
Please note! The test equipment must be properly adjusted and attached to the vehicle; observe device manufacturer's operating instructions.
Apply to the manufacturer of your vehicle alignment equipment for training as and when required.
Vehicle alignment platforms vehicle alignment units/vehicle alignment computers can lose their calibration over a period of time.
Vehicle alignment platforms and vehicle alignment units/vehicle alignment computers, should be checked and if necessary adjusted within the framework of an inspection/maintenance at least once a year!
- Treat these highly sensitive units carefully and conscientiously!
Explanation of the PR numbers 1BA, 1BC, 1BE, 1BB, 1BF and 1BP
Various suspensions are available as optional equipment. They are indicated by the PR numbers.
Suspension version installed in vehicle is indicated by the corresponding PR. No. on the vehicle data plate (arrow).
Example of a vehicle data sticker
In this example the vehicle is equipped with the standard suspension -arrow-.
The vehicle data sticker is located in spare wheel well and in Maintenance booklet.
The table shows the meaning of the PR numbers. These are critical for wheel alignment.
Measurement preparations
Special tools, workshop equipment, test and measuring appliances and aux. items required
^ VAG 1907 Steering center bolt
^ VAG 1941 Adjusting device for centering camber
^ VAG 1925 Spacer unit
^ VAG 1925/3 Adapter
^ VAG 1925/4 Adapter
The employment of adapters VAG 1925/3 or VAG 1925/4 is dependent on the hoist version.
^ VAG 1925/6 Adapter set
Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
^ VAG 1813 Wheel alignment computer
^ VAG 1869/2 Brake pedal loading device
Rim run-out compensation
The lateral run-out of the wheel must be compensated for. Otherwise the result of the measurement will be incorrect.
If the lateral run-out compensation is not performed it is not possible to adjust the toe correctly!
^ Make sure that the sliding plates and turntables are not touching the end stop when checking the wheel alignment.
^ Vehicle accurately aligned, suspension bounced and rocked several times
^ The test equipment must be properly adjusted and attached to the vehicle. Follow instructions provided by equipment manufacturer!
- Carry out wheel run-out compensation.
When doing this observe the information from the manufacturer of the wheel alignment unit.
- Install brake pedal loading device from VAG 1869/2.
Overview of work procedure for measuring vehicle
The following work sequence of steps must be adhered to!
- Check front axle camber and center if necessary.
- Check rear axle camber and adjust if necessary.
Rear axle camber adjustment only possible on vehicles with all wheel-drive.
- Check rear axle toe and adjust if necessary.
Vehicles with front wheel drive
Rear axle toe can only be centered
Vehicles with all-wheel-drive
Toe is adjustable.
Adjusting toe
- Check toe curve on front axle if necessary.
If and when the toe curve/toe constant "S" requires adjustment is described in the table on.
Checking toe constant
- Check front axle toe angle and adjust if necessary.
Allocation of adapters to suspension for measurement
Toe constant "S"
Explanation:
If a wheel suspension is compressed or extended its toe will change depending on the amount of compression or extension. The resulting toe measurements are described as the toe curve.
Changes in the toe constant "S" are made by vertically moving the head of the tie rod while the vehicle is raised.
The wheel alignment computer determines the toe constant "S" using values measured in the initial and raised positions. The computer compares the measured values with the specifications and displays them on the screen.
Depending on the suspension, various adapters are necessary for raising the vehicle.
The table on shows you the allocation of the adapter required for each running gear.
Notes:
^ An improperly adjusted toe constant leads to disturbances in driving behavior.
^ It will be noticeable when braking, accelerating or driving over undulating road.
Preparing vehicle for checking/adjustment of toe constant "S".
Suspension 1BA, 1BE
Note: It may be necessary to raise the vehicle slightly in order to position spacer gauge VAG 1925.
- If necessary, bounce the vehicle several times after lowering.
- Insert spacer gauge -VAG 1925- with adapters - VAG 1925/3 or VAG 1925/4 and screw both threaded spindles out until, they rest against the sub-frame front bolts -arrow-.
The vehicle must not be raised by doing this!
The vehicle is now in the initial position.
Vehicles with sports suspension 1BE
- Position axle lift under front jacking points and raise vehicle.
- Install adapter-VAG 1925/6- onto adapters -VAG 1925/3 or VAG 1925/4- of spacer gauge.
- Lower vehicle onto adapter.
The vehicle is now in the initial position.
Vehicles with heavy duty running gear 1BB/1BP
- Insert spacer gauge -VAG 1925- with adapters - VAG 1925/3 or VAG 1925/4-.
- Screw both threaded spindles out until they rest against the sub-frame front bolts -arrow-.
The vehicle must not be raised by doing this!
The vehicle is now in the initial position.
All types of suspension are checked in this position by the measurement program in the wheel alignment computer to make sure that the actual toe value of each wheel conforms to specifications.
If necessary, the toe must be corrected.
Setting toe on front axle to start position.
Specifications for vehicle alignment.
The alignment program will display a message only if a correction is necessary.
Raising vehicles with suspension 1BA, 1BE
For the next work sequence it must be ensured that the wheels not lose contact with the turntables during the lifting operation!
If this happens it must be ensured that the turntables do not move as this will give false results!
- Position axle lift under front jacking points and raise vehicle.
Note: The vehicle is raised by 60 mm.
- Move cylinders out of the threaded spindles and lock with securing pins.
Make sure that the securing pins -arrows- are correctly positioned!
- Lower vehicle onto spacer gauge VAG 1925.
Raising vehicles with heavy duty suspension 1BB/1BP
For the next work sequence it must be ensured that the wheels not lose contact with the turntables during the lilting operation!
If this happens it must be ensured that the turntables do not move as this will give false results!
- Position axle, lift under front jacking points and raise vehicle.
Note: The vehicle is raised by 40 mm.
- Remove adapter VAG 1925/6.
- Move cylinders out of the threaded spindles and lock with securing pins.
Make sure that the securing pins -arrows- are correctly positioned!
- Lower vehicle onto spacer gauge VAG 1925.
Vehicles pulling to one side and vehicles involved in an accident!
Vehicles pulling to one side
The cause may be the steering rack is not positioned exactly in the middle when driving straight-ahead.
Therefore the steering hydraulics are providing slight power to the left or right pulling the vehicle to one side.
When an alignment check is performed on a vehicle for the complaint "Vehicle pulls to one side or vehicle crabs" it is absolutely necessary to ensure that the steering rack is centralized.
The steering rack must be positioned exactly in the middle when setting the toe/toe constant.
Vehicles involved in an accident
Before the toe or toe constant "S" is checked or set on a vehicle which has been involved in an accident, make sure that the central position on the steering rack has been determined.
Check center position on steering rack
- Use special tool VAG 1907 to center the steering rack.
For a description of the procedure, see pages.
- Check to make sure that the steering wheel is positioned as horizontally as possible on the steering column when the wheels are in the "straight ahead" position.
- Reposition steering wheel if necessary.
- Remove special tool VAG 1907 after setting the toe/toe constant.
- Seal steering gear with hex socket head bolt -1-; tightening torque.
1. Hex socket head bolt
2. Threaded hole in steering gear