Wheelbase modifications

Why do we carry out wheelbase modifications?

The wheelbase of a chassis is critical to its legality on the road and the ability to carry the optimum amount of product, whether that is goods for delivery or fixed equipment.  If a chassis has the wrong wheelbase for the application, a number of things can result, of which more than one of the listed problems can affect a single vehicle:-

• One or more axles can easily become overloaded.
• The potential payload of the vehicle may be reduced to maintain correct axle weights.
• If the wheelbase is too short, the rear overhang can become excessive and possibly illegal.
• If the wheelbase is too long, the vehicle can become difficult to manoeuvre.
• An incorrect wheelbase can restrict the ability to operate with the optimum length of trailer, whether that is a semi-trailer or a drawbar trailer.

How do we modify a wheelbase?

The specification of the chassis to be modified will normally dictate the method used to extend or reduce the wheelbase.The favoured method is to move the rear axle position be sliding the suspension along the original chassis and then extending the frame at the rear to accommodate the required body length. This sounds simple, but can be and often is very complex. The other method used is to cut the original chassis between the axles and insert a section of chassis frame. This is quite often the only way in which a wheelbase modification can be achieved due to the nature of the original build or the extent of the changes required. Having modified the wheelbase, the drive line and services have to be reworked to suit.

When a wheelbase has been completed it should have the same integrity as the original chassis and if it has been carried out well you will be hard pressed to ‘find the join’.

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