The rear wings on an MGB are prone to rust around the wheel-arch joint between the outer wing and the inner wheel-arch. Replacing the lower section of the outer wing (which has been described in Rear Wing Repair page) and replacing the outer half of the inner wheel-arch can rectify this. Ideally these two repairs should be carried out together, although it is possible to do each separately. The wheel-arch is part of the integral strength of the vehicle and care should be taken over this work. In addition the inner half of the wheel-arch carries one of the anchorage points for the seat belts on some cars and must be in sound condition.

As always fire and safety precautions should be observed to ensure that work is carried out safely without risk of injury.

A certain amount of cutting and welding will take place so the fuel tank, fuel pump and fuel lines should be removed as a safety precaution. The wiring loom passes over the rear wheel-arch and should be protected during the work. Also the batteries should be removed because they can give off an explosive gas. To begin the work the car should then be raised to a convenient height and place on suitable ramps or blocks to allow the rear wheels to be removed and to allow safe working underneath where required.

Start by estimating the rust damage and buying the new panels as required. Whilst assessing rust damage check the boot floor extension panel because this would be a good opportunity to replace it if necessary. Good MG specialist suppliers carry stocks of the necessary repair panels. Where both repairs are to be made together start by removing the lower section of the outer wing as described in page Rear Wing Repair and the remove the outer half of the inner wheel-arch panel. Take note of the fact that the rear of the sill is attached to the wheel arch cut and will need to be re-attached later. Sills are an important part of the integral strength of the vehicle and this should not be overlooked.

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Remove the old metal by offering up the new panel and assessing where to make the leaving sufficient overlap to allow for joining new metal to old. Cut off the rusted portion without distorting the remaining section and an angle grinder with a metal cutting disc would be ideal for this. Next fit the new outer wing section securely into place as described in Rear Wing Repair and offer up the inner wheel-arch repair panel. Trim the old wheel-arch section to allow the new section to fit and use a Joddler tool on the edge to form an overlap for welding. Some trimming and dressing on both panels will be necessary to achieve a good fit. Once you are happy with the fit attach the new panel securely in place by using Cleco fasteners and then remove the new outer wing section. If this repair is carried out before the new outer wing section is welded into place it makes the task of welding the wheel-arch section much easier. However, you must be certain that you have positioned the outer wing correctly otherwise the two panels will not align properly. Weld the new outer wheel-arch section into place using a seam weld between old and new panels. Seam weld in short sections to avoid heat distortion. Then weld the flanges on the rear of the sill and the boot floor extension panel to the new metal. As the joint between inner and outer wheel-arch will be visible in the boot take particular care to make a neat job at this point. Before fitting the new outer wing section it is a good opportunity to apply some paint to the inner surfaces of the wheel-arch to prevent a recurrence of the rust problem. Anti-rust wax proofing should also be applied to these areas when the job is finished.

Once the wheel-arch has been repaired the new lower panel can be fitted as described in Rear Wing Repair and spot or plug-weld the flanges between the new wheel-arch and the new outer wing. The final task is to apply seam sealer to the welded joints and to underseal/repaint as desired.

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