P46.20-2233-07
Shown on a hydraulic rack and pinion steering as an example
P46.20-2235-07
Shown on a hydraulic rack and pinion steering as an example
TÜV (Technical Inspection Association) and/or MB workshops complain about too much play in the rack-and-pinion steering, but are using an unsuitable testing method.
For this reason when checking the play in the steering box, please only use the method described in the following.
All other tests are not suitable for evaluating the play in the rack and pinion steering, which has an influence on the driving and steering characteristic of a vehicle. These methods only lead to incorrect diagnosis of play in the steering system. In this respect we ask that you please inform the testing organizations about vehicles tests as per paragraph 29.
The cause of this is an incorrect testing method or an incorrect evaluation of the play in the steering system!
Radial movement of the input shaft or of the rack at the left and right is evaluated as play.
Radial movement of the steering coupling at the input of the control shaft (see figure, item 1) are not relevant for evaluating play. Radial movement that can be felt should not be evaluated as play in the steering box. This does not have any influence on the function of the rack-and-pinion steering, steering play or the vehicle dynamics. Likewise it behaves with radial movements at the toothed rack or tie rods (see Picture item 2), in particular with steering turned through an angle. In this position the rack is extended to one side and acts as an even larger lever where supposed play can be felt even more (checking play at the outer and inner joints remains the same). Radial movement when applying pressure in this case is normal and is due to the construction of the steering system.
When quickly turning the steering wheel left/right, especially with engine off (no power assist), a more or less loud clunking noise can be heard. This is also due to the steering system's construction and is in no way evidence of play in the steering system.
Play test as per Mercedes-Benz specification:
Prerequisite: The steering column and the outer and inner joints of the tie rods must not have any play.
The play of the rack-and-pinion steering itself must only be performed
with the vehicle stationary
with the engine running (power steering assistance must be operable)
and with the front wheels in the straight-ahead position.
The steering wheel must be turned slowly while watching the rims move. The rims must follow the steering movement at the latest after a travel of approx. 12 mm at the circumference of the steering wheel. During this movement a steadily increasing in pressure can be felt in the steering wheel. This delay is the result of flexibilities in the steering (steering connection etc.) and it is not a complaint.
In order to properly evaluate play in the rack-and-pinion steering system, only the axial movement of the rack in relation to the steering box is relevant (which is being measured by the above procedure, see figure, item 3).
This invalidates all publications on this topic with different content; such publications have been adapted appropriately.