Retrofitting mechanical detachable parts - AN31.11-P-8080-05N

TRAILER COUPLING MECHANICAL SYSTEM

Number	Designation		Models 215, 220
BA31.11-P-1001-01A	Nut, trailer coupling to rear center assembly	Nm	50
BA31.11-P-1002-01A	Bolt, trailer coupling to side member reinforcement	Nm	110
BA31.11-P-1003-01A	Collared nut, side member reinforcement to frame side member	Nm	43
BA31.11-P-1004-01A	Bolt, bumper to bumper reinforcement	Nm	8

Drill dia. 6.5 mm holes in side member at the positions (A) marked by punch marks, enlarge holes to dia. 14 mm, deburr and prime.
The punch mark at the transition from the rear center assembly to the side member is usually hidden behind underbody sealant. Use the holes in the trunk side compartments as reference marks.

Fig 1: Identifying Rear Center Assembly Inside Holes Dimensions
Measure the centers for the holes on the insides of the rear center assembly (as shown in Figures A and E), enlarge to dia. 32 mm, deburr and prime.
Enlarge cable openings (see Figures B and D) to dia. 36 mm, deburr and prime.
There are punch marks at the centers of the embossed circles. Make sure that no cables on the inside are damaged.
Mark out the holes for the wiring harness brackets according to the dimensions in Figure C (both holes are marked by punch marks), drill holes to dia. 6.5 mm through the outer skin only , deburr and prime.
Reference point (for dimensions) see arrow in Figure C.

Fig 2: Identifying Side Member Punch Marks
Coat the opening (see arrow in magnified section) in the sealing wedge (5) with acid-free grease or soap.
Push in the left and right side member reinforcements (7, 6) through the sealing wedge (5) on the crossmember (2).
Tighten the left and right side member reinforcements (7, 6) finger-tight with two bolts (11) each.
Screw two threaded bolts (12) (see figure) into each of the left and right brackets of the crossmember (2); the flange on the threaded bolt must be max. 13 mm away from the tapped hole (see dimensions).

Fig 3: Identifying Side Member Reinforcements Components
Fit alignment punch (18, 17) on inner threaded studs (see Figure).
The alignment punches are different for the left (18) and right (17) sides.
Push preassembled trailer coupling (2) into vehicle side member.
Bolt trailer coupling (2) onto rear center assembly with three combination nuts (9) on each side, tightening the two outer combination nuts (9) first, removing the alignment punches and then fastening the inner combination nuts (9)
The combination nuts (9) can be accessed via the trunk.

Fig 4: Identifying Trailer Coupling Components
Tighten side member reinforcements (6) with counter tabs (8) and collared nuts finger-tight to the side member.
The collared nuts (10) can be accessed via the side compartments in the trunk.
Use hexagon bolts (11) to attach trailer coupling (2) to side member reinforcement (6)
Attach side member reinforcement (6) to side member using collared nuts (10)
Pass control cable (1c) and release switch connecting cable (1b) through the hole under the left tail lamp and seal with grommet (i).

Fig 5: Identifying Control Cable And Release Switch Connecting Cable
Remove bumper bracket (20).
The bumper bracket is attached with four bolts (see arrows). The bumper bracket and bolts are no longer required.

Only for vehicles on which the holes (see small arrows) in the bumper covering are fitted with metal bushings

17.1 Drive out metal bushing (see small arrows) and enlarge the hole to dia. 14 mm.
This step is not required on bumper coverings without metal bushings.
18 Bolt bumper bracket panel (3) provided onto bumper covering using bolts with captive washers (14) provided

Fig 6: Identifying Bumper Bracket With Bolts And Metal Bush