General:

• For a secure connection between the vehicle chassis and body, a subframe or base structure which takes over the function of a subframe (with the exception of self-supporting custom bodies and subframes as floorpan assembly), is necessary for all custom bodies.
• The subframe longitudinal members should be level and rest on the upper belts of the vehicle chassis, following the run of the frame.
• For VW Crafter 5.0t models (twin wheel version):
  The vehicle chassis frame longitudinal members are offset inwards in the rear axle area. There is no necessity for the subframe longitudinal members to follow this angle and can be finished to run on in a straight line. Wooden strips between the vehicle chassis longitudinal members and subframe longitudinal members are not permissible. Console attachment is necessary in the area of the rear axle above the subframe cross member 
• Position subframe cross members above vehicle chassis cross members.
• For the longitudinal members, use folded U section or commercial-type U section, as used in body assembly (do not use rolled steel section) Box sections are also permissible.
• The dimension of the longitudinal members is calculated from the required resistance moment (Wx) for body and vehicle chassis. See diagram 3.3.2. The resistance moments and profile dimensions given are based on the frame longitudinal members being placed under the same load on both sides.

If more than one custom body is fitted to the chassis (e.g. drop-side and loading platform), the larger of the prescribed resistance moment figures must be applied for fixture of the subframe.

Subframe as floorpan assembly:
A subframe with continuous longitudinal members is not necessary if the floorpan assembly of the body can take on the function of the subframe.

Material qualities for prescribed subframes made of steel:
Design subframes with console attachment (positive connection) as H 240 2A or S235 JR 62 type.

Subframes made from high tensile steels must be at least as stiff as steel subframes. Attachment must be of the positive type.

Drop-side bodies with aluminium design

• Observe information from aluminium manufacturer
• Longitudinal members, planked flooring, base plate and traverses must form one self-supporting unit.

The profile overhang at the front ends of the longitudinal members should be gradual. Profile dimensions
Profiles for subframe longitudinal members (open profile), subframes and vehicle chassis frames should have approximately the same material thickness and flange width.

If very high longitudinal members are necessary or if low frame heights are aimed for, the U section on positive connections can be

• closed on panel vans
• boxed inside each other
• boxed.

In this way, the resistance moment is raised and also the torsional strength. Ensure the transition is good from closed longitudinal member to open U section.