This work requires special equipment and cannot be done independently, so here we will only cover the basic concepts.
Convergence
Toe-in is the lateral distance between the wheels. As a rule, the front wheels should have a positive toe-in, since due to rolling resistance they tend to diverge when moving in a straight line. When specifying a positive toe-in for the front wheels, the distance between them is measured at the height of the wheel centers - at the front it should be slightly less than at the rear.
With negative toe-in of the front wheels, the distance measured at the height of their centers should be slightly greater at the front than at the rear.
On a Mercedes, both the front and rear wheels can be adjusted for positive toe-in.
Front wheel camber and kingpin angle in the transverse plane:
Front axle:
- St - Collapse.
- Sp - Angle of inclination of the kingpin in the transverse plane.
- LR - Turning radius.
- 2 - Crosspiece.
- 4 - Lower control arm.
- 5 - Steering knuckle.
- 6 - Upper control lever.
- 7 - Lower ball joint.
- B - Upper ball joint.
- 19 - Eccentric bolt for adjusting wheel alignment.
- 49 - Support tube.
Correctly set wheel camber and kingpin angle in the transverse plane soften the shocks transmitted from road irregularities to the steering and reduce tire friction on the road when turning.
Camber is the angle between the plane of the wheel and the vertical. With positive camber, the distance between the front wheels at the bottom is less than at the top. The turning radius of a Mercedes is zero.
The angle of inclination of the front wheel kingpins in the longitudinal plane:
Front axle:
- NL - Angle of inclination of kingpin in longitudinal plane.
- VLV - rear wheel camber.
- 1 - Side element.
- 2 - Crosspiece:
- 4 - Lower control arm.
- 5 - Steering knuckle.
- 6 - Upper control lever.
- 8 - Upper ball joint.
- 10 - Stabilizer.
- 19 - Eccentric bolt for adjusting wheel alignment.
- 21 - Rubber bushing of the stabilizer.
- 48 - Ball joint.
- 48a - Ball joint for adjusting the steering angle of the front wheels.
- 49 - Support tube.
The angle of the kingpin in the longitudinal plane is determined relative to the vertical drawn through the wheel axis. The angles of the kingpin inclination, both in the longitudinal and transverse planes, are adjusted using two eccentric bolts.
The caster angle of the kingpins affects how well the front wheels "hold" the straight-line. Too little caster angle causes deviations from the straight-line on poor roads or in strong winds, and also prevents the steering mechanism from returning to the center position after completing a turn.
Adjusting the front wheel alignment angles
To adjust the front wheel alignment angles, you will need a pit or lift. Before you begin taking measurements, check the following:
Is the tire pressure correct?.
The car must be empty, the fuel tank must be full, the spare wheel and tool kit must be in place.
Check the steering adjustment.
Check the steering rods for excessive play.
Check the wheel suspension for excessive play.