General Installation Instructions:
Beginning in 1990 the spanner sizes of hexagon bolts and nuts were converted to those
contained in ISO 272. Please check the respective spanner size and use only the matching tool.
If present, remove insulating compound and/or underseal in the area of the CBB contact
surfaces. Coat bare bodywork with anti-corrosion paint.
Mount 7-pin electrical system as per DINV 72570.
Mount 13-pin electrical system as per ISO 11446.
Apply the trailer nose-weight plate to the vehicle near the CBB or in the luggage boot in an easy-
to-see location
Retighten all mounting bolts of the CBB after approx. 1,000 towing km.
This CBB including all mounting parts weighs 16.8 kg. Please take into account that the curb
weight of your vehicle is increased by this amount after mounting the CBB.
Available Spare Parts for Coupling Ball with Bracket
Spare Part No.
903 121 650 001
903 078 601 001
903 051 630 106
M10x30
M10x30
M10
Description
Pack. Mounting parts
Pack. Ball fitting including sealing plug
Pack. Sealing plug
M10x30
M10x30
M10x30
303 121 / 123 / 124 691 101
M10
GB
M10x30
3
