Leaving the Frame on the Chassis
If the sill boards are in good condition it would be possible to leave the frame attached to the chassis when replacing the door rocker, but most of the body panels will have to be removed. There are two screws securing the front end of the rocker to the scuttle post as illustrated in Figure 2. These screws are concealed by the bulkhead. Two methods are available to gain access to the screws.
The first method requires releasing the frame from the chassis and sliding it backwards, but this involves replacing the damp proof course between the chassis and the frame. Having lifted the frame to carry this work out, you may as well replace the rocker at the same time.
The alternative involves removing the bulkhead which requires a lot of work, but during a rebuild the bulkhead will most probably have been removed anyway. The advantage of leaving the frame on the body is that it will retain its shape and will not need to be stored elsewhere whilst working on other parts of the car.
Gaining Access to the Door Rocker
I have seen repairs where sections of wood have been cut away and replacement timber scarved in. This does allow a repair without stripping too much of the car, but it is preferable to replace any damaged frame components with a new parts. This requires stripping body panels to gain access. The main body panels requiring removal are illustrated in Figure 3. These panels are pinned and screwed along their edges. Unfortunately the wings have to be removed to gain access to these fastenings. See pages on 'removing the front wings' and 'removing the rear wings'
If the door rocker is rotten, the quarter panels, triangular fillet pieces and lower parts of the scuttle will usually be corroded as well. If this is so, make templates before removing them. When the scuttle has been removed, the scuttle frame may become unstable due to rot in the ash frame. Use pieces of timber or plywood to construct temporary stabiliser struts as shown in Figure 3. Similar struts are used during the manufacture of the frames at the factory.
Rot in the Door Rocker
When I stripped my own frame, the nearside door rocker was so rotten, I had to take a pattern from the offside one. The hinge and latch posts had also deteriorated. The door will not fit properly if these three components are not made accurately. They must also be positioned correctly on the sill boards. This is where the use of templates is critical. Both of my own sill boards were thoroughly rotten, but the offside one had enough good wood remaining to trace an accurate template. This helped in producing a pattern for the extremely rotten nearside sill.
Removing the Door Rocker
Always work on one side of the frame at a time. This should help in ensuring the frame keeps its original shape. Temporary battens fixed diagonally across the top of the frame should help prevent any distortion.
As the sill boards are prone to rot, it is usually necessary to remove the ash frame from the chassis before the door rockers are replaced. It is possible to replace a sill board without removing the frame from the chassis. However the opposite board retaining bolts have to be loosened to allow the frame to be tilted. As mentioned above, the damp proof course must be replaced when disturbed. To do this properly requires the chassis to be cleaned and painted, so it is better to remove the frame before working on it. When a rotten frame is removed from the chassis, there is always a risk that it will twist. It is therefore essential that the stabiliser struts have been fitted before the lift. Once this has been done, removing the door rocker is straight forward.
Stand the frame on a flat stable surface. Undo the three screws at the base of the latch post. Remove the two screws securing the latch post block and undo the two screws joining the top of the latch post to the elbow joining piece as illustrated in Figure 5. The joints may have also been glued, in which case they will have to be prised apart. If the latch post needs replacing, remove and save the wedge.
Remove the three screws at the base of the hinge post and undo the two screws at the top which attach it to the dash board support rail. Remove the post, but do not unscrew the steel plate attached to its rear edge. If you have to make a new hinge post, the steel plate will provide a perfect template for drilling the holes for the hinges on the new one. Keeping it screwed to the original post ensures it is correctly orientated and matched when re-fixing to its replacement.
Remove the two screws securing the front end of the door rocker to the scuttle post. If the rocker is extremely rotten, try to make a template, before finally undoing the screws that fix the door rocker to the sill. Make sure the template for the sill board has the alignment of the door rocker clearly marked on it.
Replacing the Door Rocker
With most side components removed, the frame will be at its most fragile. Ensure it stands on a flat surface whilst working on it and if the sill boards need replacing, do one side at a time.
The old sill board template must have the position of the door rocker clearly marked before removing it. Sill board templates should also have the positions for mounting holes perfectly marked, which allows accurate alignment when refitting the frame to the chassis. After each sill is replaced, the frame can be lifted back onto the chassis to check the alignment.
Before assembling the new door rocker, the sill boards MUST be fitted to the frame, which should have been checked for alignment with the chassis, . Align the rear half lap joint of the rocker with the corresponding lap joint on the sill board. The front end of the door rocker should align with the screw holes in the scuttle post. If you made the part yourself and checked the accuracy of your templates whilst the sill boards were in place, the rocker should be a good fit. At this stage lightly screw the door rocker in place.
Lightly screw the hinge and latch posts in place. If you are happy with the accuracy and tight fit of the joints, check that the door frame fits properly. When you are happy that everything fits, use a good quality urea-formaldehyde glue and stainless steel screws to finally assemble the joints. Allow 24 hours for the glue to set before disturbing the frame.