Alignment: Service and Repair

WM 449503 Suspension alignment, complete

Tools

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).

Tyre pressure in accordance with regulations, fairly uniform tyre tread.

Quick-clamping holder with adapter (for the measured-value pickups) correctly secured to the wheels. Different procedure for vehicles (wheels) with central bolts!

Use self-centering quick-clamping holders => WE1265 Porsche Quick-Clamping Unit to secure the measured-value pickups on the wheels. Any previously used quick-clamping holders that are available can also be used. Cannot be used for vehicles (wheels) with central bolts.

The self-centering quick-clamping holders are positioned centrally (with the claws first) in the centre of the rim and are tautened 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 levelling 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 levelling of the measuring platform or measuring station is done in-house, levelling 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 tyres, tyre wear and cost/benefit effects (time required for correction of insubstantial deviations). The toe values are of decisive significance for driving dynamics and tyre 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 centre 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=> Adjustment values for wheel alignment.

Rear axle

Measure from wheel contact surface to the locating bore in the rear-axle side section (between toe and camber eccentrics).

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 PIWIS Tester II 9818.
-> Keep the front wheels in straight-ahead position on the measuring platform during calibration.
-> On vehicles with electromechanical steering, also re-teach the electric steering lock settings.

1. Prepare vehicle for checking and/or adjustment of wheel alignment values.
2. Place front wheels on rotary table and rear wheels on rotary/sliding plates.
3. Compress vehicle at front and rear axles by approximately 25 mm 2-3 times and allow it to spring back freely.

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

Turn the eccentric accordingly -B- after releasing the fastening nut using special tool Insert for torque wrench 96260.

Special tool 96260 (Insert for torque wrench)

Adjusting toe

Turn the eccentric accordingly -A- after releasing the fastening nut using special tool Insert for torque wrench 96260.

Toe and camber eccentrics

Information

- Use special tool 9626 in combination with a torque wrench to undo and tighten the fastening nuts of the toe and camber eccentrics. The prescribed lock-nut tightening torque of 100 Nm (74 ftlb.) also corresponds to a setting on the torque wrench of approx. 100 Nm (74 ftlb.).

Tighten fastening nut for toe eccentric to 74 ft lbs using special tool Insert for torque wrench 96260 , with a torque wrench.

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, centre the steering gear as described below.

Turn wheels to the straight-ahead position.

Then readjust the front wheel alignment, if necessary, until pin -2- in driver -1- and lug on steering gear housing -4- , line up.

Steering in centre position

No. 3 is the desired breaking point for pins in new steering gears. The (new) pin -2- is inserted into driver -1- and its underside sits in lug -4-. This locks the steering gear in the centre position. After installation of a new steering gear, the lower part of the pin is sheared off at desired breaking point -3- ) by turning the steering wheel. The upper part of the pin -2- remains in the driver.

Steering in centre position

If necessary, reposition the steering wheel. When doing this, seek the best position.

Mark for the centre steering position

WARNING

Unsuitable steering-wheel holder used

- Triggering of airbag unit

-> Use only steering wheel holders that do not project into the area of the airbag unit during suspension alignment work.
-> Observe the safety regulations for handling airbag units.

Clamp steering wheel in centre 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 guide rod of steering-wheel holder at the top -arrow-.
For fast and reliable steering wheel alignment in the centre position use a -steering wheel balance- (with integrated angle measurement box) => WE1343 Steering wheel balance.

Steering-wheel holder

Steering wheel balance

Release tie rod locking nut(s) -2-. When undoing or tightening tie rod locking nuts on the square part of the tie rod -3- , with a spanner, apply counter-pressure. Next, adjust toe at the hexagonal part -1- of the tie rod(s). Then tighten tie rod locking nuts -2- with the specified tightening torque.

Adjusting toe

To loosen and tighten the tie-rod lock nut(s), use special tool (socket-wrench insert) P 9730 -A- together with a torque wrench -B-. The tightening torque for the tie-rod lock nut(s) of 50 Nm (37 ftlb.), when using a socket-wrench insert 9730 , corresponds to a value of approx. 32.5 Nm (24 ftlb.) on the torque wrench.

Loosening and tightening the tie rod-lock nut

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.