Alignment: Service and Repair
Suspension alignment, complete
Information
General procedure for wheel alignment
Perform wheel alignment using an electronic wheel alignment tester. Measurement procedures should be taken from the operating instructions for the wheel alignment tester used.
In order to exclude erroneous measurements, the following preconditions must be met before alignment and the following points should be given special attention:
Unladen weight of vehicle according to DIN 70020, i.e. vehicle in ready-to-drive condition with full tank and including tools but without driver or additional weights.
Ball-joint and wheel-bearing play in order (wheel-bearing play cannot be adjusted).
Tire pressure in accordance with regulations, fairly uniform tire tread.
Quick-clamping holder with adapter (for the measured-value pickups) correctly secured to the wheels.
Use self-centering quick-clamping holders to secure the measured value pickups on the wheels. Any previously used quick-clamping holders that are available can also be used.
The self-centering quick-clamping holders are positioned centrally (with the claws first) in the center of the rim and are tightened in the rim by turning the straining ring (clockwise).
Self-centering quick-clamping holder
Receiving surfaces for the quick-clamping holder on the wheels and the adapter surfaces must be clean and flat. Always check the leveling surface on the wheels precisely in particular before fitting the quick-clamping holders.
Strictly comply with maintenance intervals for measuring equipment and measuring platform. If the leveling of the measuring platform or measuring station is done in-house, leveling equipment is required. A spirit level is not adequate.
Skilled handling of measuring equipment and measuring platform.
Sliding plates with transverse motion (rotary motion) at the rear axle are advisable.
Observe the Technical Literature of PAG, the manufacturer of the measuring equipment and the manufacturer of the measuring platform.
Do not treat measured values as a whole, but very critically with regard to driving dynamics, high-speed strength of the tires, tire wear and cost/benefit effects (time required for correction of insubstantial deviations). The toe values are of decisive significance for driving dynamics and tire wear.
If the vehicle is measured front and rear, check and adjust the wheel alignment values at the rear axle first. Camber values at the front axle apply for the straight-ahead position of the wheels. Steering wheel and steering gear in center position when toe is being adjusted.
Before wheel alignment values are adjusted at front and rear axles, it is recommended that the vehicle height be checked at the DIN empty weight. Conclusions can then be drawn about wheel alignment values in the event of any suspension alignment that becomes necessary later.
Aligning vehicle at front and rear
Vehicle height (height check)
General
The vehicle height at front and rear axle is not adjustable.
Preliminary work
For the height check, place the vehicle on a level surface or on the measuring platform (ready to drive, with a full tank and tools but without driver or additional weights). Compress (push down) vehicle at front and rear axles 2-3 times and allow it to spring back freely.
Front axle
From road contact surface to hexagon-head bolt of cross-member screw connection to the body.
Measuring height of front axle (left hand side)
Nominal value for front and rear axles.
Rear axle
Measure from wheel contact area up to lower edge of diagonal brace (at control arm fastening point).
Measuring the height of the rear axle (right-hand side)
Wheel alignment
Warning
Steering-angle sensor not calibrated or calibrated incorrectly
Unexpected vehicle handling
Steering-angle sensor does not function
Malfunction in steering-angle sensor
- After working on wheel suspension parts, when replacing the steering-angle sensor, and after changing the wheel alignment values, calibrate the steering-angle sensor using the PIWIS Tester 9718.
- Keep the front wheels in straight-ahead position on the measuring platform during calibration.
- Check the actual value of the steering-angle sensor after suspension alignment where no changes were made to the wheel alignment values.
Notes
Only check or adjust wheel-alignment values when prescribed preconditions are met.
If the vehicle is measured front and rear, check and adjust the rear axle first. After adjustment, tighten the appropriate screw connections to the prescribed tightening torque.
The steering-angle sensor must be calibrated if the previous wheel alignment values (on rear and/or front axle) were changed!
Rear axle
Preliminary work
Prepare vehicle for checking and/or adjustment of wheel alignment values. Place front wheels on rotary table and rear wheels on rotary sliding plates. Compress vehicle at front and rear axles by approximately 25 mm 2-3 times and allow it to spring back freely.
Adjusting camber
After loosening the lock nut, turn eccentric -B- appropriately.
Toe and camber eccentrics
Information
Due to the restricted space, to tighten the lock nut of the left camber eccentric, use a 3/8 inch torque wrench (covering the range of 100 Nm (74 ftlb.)) together with a 18 mm socket-wrench insert.
3/8 inch torque wrenches and 3/8 inch socket-wrench inserts have a smaller height than tools of the same size in a 1/2 inch version.
Tighten lock nut from camber eccentric to the prescribed tightening torque. To do this, use a 3/8 inch torque wrench (covering the range of 100 Nm (74 ftlb.)) together with an 18 mm socket wrench insert on the left side.
Adjusting toe
After loosening the lock nut, turn eccentric -A- appropriately.
Toe and camber eccentrics
After adjusting, tighten the lock nut of the toe eccentric to the prescribed tightening torque.
Front axle
Adjusting camber
The camber is adjusted by moving the spring strut transversely. For this purpose, undo the three fastening nuts on the spring-strut mount and, to move the spring strut, remove the covering cap on the piston rod.
Adjusting camber
Adjusting caster
The caster is not adjustable on standard vehicles.
Adjusting toe
Preliminary work: Check whether the steering wheel is displaced with respect to the steering gear. To do this, center the steering gear as described below.
Turn wheels to the straight-ahead position.
Then re-adjust the front wheel alignment, if necessary, until bolt -2- in driver -1- and the lug on the steering gear housing -4- line up.
Steering in center position
No. 3 is the desired breaking point for bolts in new steering gears. The (new) bolt -2- is inserted into driver -1- and lies with its underside in lug -4- This locks the steering gear in the center position. After installation of a new steering gear, the lower part of the bolt is sheared off (at desired breaking point -3- by turning the steering wheel. The upper part of the bolt -2- remains in the driver.
Steering in center position
If necessary, reposition the steering wheel. When doing this, seek the best position.
Mark for the center steering position
Warning
A triggering of the airbag (malfunction in the airbag system) caused by improper work on airbag components cannot be ruled out. In the case of such a malfunction, an unsuitable steering wheel holder could cause injury or damage.
- Use only steering wheel holders that do not project into the area of the airbag unit!
- Observe safety regulations when working with airbag vehicles!
Steering wheel holder
Clamp steering wheel in center position with steering wheel holder -A-. Use only steering wheel holders that do not project into the area of the airbag unit -B- If necessary, shorten the guiding rod of the steering wheel holder at top -Arrow-.
Loosen tie rod lock nut(s) -2- When loosening and tightening the tie rod lock nut(s) counter on the square of the tie rod -3-, with an open ended wrench. Then adjust the toe on the hexagon -1- of the tie rod(s). Then tighten the tie rod lock nut(s) -2- to the prescribed tightening torque.
Adjusting toe
Use special tool (socket wrench insert) P 9730 -A- together with a torque wrench -B- to loosen and tighten the tie rod lock nut(s). The tightening torque of 50 Nm (37 ftlb.) for the tie rod lock nut(s) corresponds to a value of approx. 32.5 Nm (24 ftlb.) when using a socket wrench insert P 9730.
Loosening and tightening tie rod lock nuts
Toe-difference angle
The toe-difference angle is not adjustable.
The steering angle sensor must be calibrated if the previous wheel alignment values (on rear and/or front axle) were changed.