(Chassis with single/crew cab)

If the wheelbase is changed and in the event of overhang extensions, the material of the extension piece must be the same in quality and size as the vehicle chassis frame (St 12.03). Changes to the structure should not impair the function and clearance of assemblies and control equipment, or the strength of
supporting structures.

Apertures in the cab partition must be fitted with a surrounding frame. The remaining struts and cross members must be reinforced with plates and welded to the inserted frame.

The distance between cab and body must be at least 50 mm.

Frame modifications

• The permissible axle loads must not be exceeded and changes should not affect the minimum front axle load.
• Attach underbody guard in line with series production vehicle.
• Extend subframe up to end of frame.
• Check the function of the tow hitch.
• Reinforcements must be in place for tow hitches if desired.

The longitudinal members are of the hollow type (hat section). If holes need to be drilled in the members, it may only be done in the specified areas.

Drilling is not permitted in the following areas:

• In the upper and lower belt of the chassis frame. Exceptions are holes in the rear frame end. However, they must not be in the area of parts that function to support the rear axle and parts attached to the frame.
• In the area of section changes to the frame longitudinal members (frame offset and frame draw-in).
• At load distribution points (e.g. in direct vicinity of spring brackets).

In exceptional cases, holes can be made in the web of the frame longitudinal members.

• Use of spacer sleeves welded on longitudinal member (see diagram below)

After drilling, deburr and ream. Before installation, spacer sleeves must be welded in. Remove swarf from the frame and apply cavity protection.

The max. perm. rear overhangs (depending on wheelbase) are to be adhered to in accordance with item 2.3.1.

Observe the following to do this:

• On frame extensions longer than 350 mm, an additional cross member must be installed.
• Overhang extensions are to be performed as per diagram shown below.
• Additional frame cross members must have the function of a series cross member.
• If the frame cross member is extended, the permissible axle load given in the vehicle documents must be checked and reduced if necessary until omission.
• The permissible axle loads, the permissible centre of gravity positions and the minimum front axle load are to be adhered to in all load conditions (see 2.1).
• As a preparatory measure in the factory, the tail light cluster wire (PR no. 8SE) can be installed.
• Standard body consoles must be used at the end of the frame.

Wheelbase modifications on vehicles with electronic stabilisation programme (ESP) are not permitted.

Extend the wheelbase from the longest standard version. Shorten the wheelbase from the longest standard version. Reinforce the cutting point with panel blocks.

Wheelbase modifications by offsetting the rear axle are not permissible.

Cutting points must not be made in the areas of:

• Load distribution points
• Axle guide and axle suspension
• Profile section changes (frame offset, frame retraction

Following wheelbase modifications, the chassis must be reinforced with a subframe throughout the structure.

Resistance moment figures necessary for the subframe:

• Up to max. series production wheelbase 30 cm3.
• Increase above max. series production wheelbase by at least 15%.

The wheelbase modification results in alterations to the turning circle and weight specifications.

Wheelbase modifications that lie in the frame of the smallest or largest series production wheelbase need not be submitted for approval.

Inserting inlays in frame

1. Separation points welded all round
2. Plug weld, hole diameter 12 mm
3. Material quality of hat profile used
4. Inlay material at least St 12.03, Material thickness 2 - 3 mm
5. Upper belt inlay (inner)
6. Lower belt inlay (outer)

If the overhang extension also involves extension of the assembly frame, the weld seams must be offset by at least 100 mmin line with series production.

On change to wheelbase, ensure that end of tail pipe is not aimed towards a tyre.

Following wheelbase modifications, the chassis must be reinforced with a full assembly frame.

Cut area of frame

Figures refer to chassis with cab Distance from centre of front axle