Removing the Repairing Latch Post and Elbow Rail

The latch post is prone to rot in the lower joint, where it is joined to the door rocker and sill board. The underside of the sill board surrounding the latch post joint is partially protected by the rear end of the front wing as illustrated in Figure 1. When the car was manufactured, the sill boards were undersealed after the front wings were attached. Water mixed with road grime streams off the front wheels on rainy days and saturates the area and accumulation of mud discourages it from drying out. Because of the way timber and steel flex in different ways, the contact area between the wing and the sill is prone to leak, resulting in water becoming trapped between the two. During re-construction of the car, use a good quality exterior flexible sealant between the wing and sill board. This should help prevent the ingress of water between the two.

Due to capillary action, wood absorbs more water on the end grain, than it does across the grain. Unfortunately the half lap joint of the sill board, door rocker and latch post, all have end grain exposed, causing all three susceptible to rot.

The rot shown in Figure 1 reveals the condition in the offside sill board before the rebuild. The nearside sill was much worse. Both latch posts suffered as they absorbed water from the rotten sill boards.

Gaining Access to the Latch Post

Figure 1

Replacing Latch Post

To gain access to the latch post and elbow rail, you must remove the quarter panel as shown in Figure 1. Unfortunately the rear and front wings, must be removed first. It may seem extreme to remove the front wings, but their rear ends overlap the lower flange of the quarter panels as illustrated in Figure 1. When the wings have been removed, releasing the quarter panel is straight forward. See " Removing and Repairing the Quarter Panel" under "Bodywork" in the main menu. It is highly likely that wet rot in the latch post and sill board will have caused the quarter panels to corrode. Make sure to make accurate templates before removing the quarter panels and any rotten wooden parts.

Figure 2

Replacing Latch Post

Removing and Replacing the Latch Post

Figure 3

Replacing Latch Post

If only the latch post needs replacing, the ash frame can be left on the chassis with the bulkhead attached as shown in Figure 2. However this is unlikely as rot in the lower latch post is usually associated with rot in the sill board. If this is the case, remove the scuttle and undo the bulkhead securing screws, then release the ten coach bolts and two hexagonal bolts which secure the ash frame to the chassis.

It would most probably be possible to free the frame enough to replace sill boards without removing the frame completely from the chassis, but many fuel lines and cables would have to be released and replacing the damp proof course without thoroughly cleaning the chassis would be pointless. At this stage remove the ash frame.

Fit temporary stabiliser struts across the frame as shown in Figure 3. It is advisable to replace parts on one side of the ash frame at a time, and always replace the worst condition side first. Hopefully the better side of the frame will be strong enough to maintain its shape sufficiently. Extra temporary stabiliser boards can be screwed diagonally across the top of the frame to stop it from distorting.

Simple lap joints are used to fit the latch post. Three screws secure the lower end of the post to the door rocker and sill board. A block fixed on the inside of the latch post encompasses the rear end of the door rocker. Four screws attach the rear of the latch post to a substantial steel bracket, which is bolted to the sill board, as illustrated in Figure 3. The top of the latch post is connected by half lap joints to the elbow rail by a 12mm thick fillet of wood secured by 4 screws. The elbow rail is screwed to the laminated wheel arch and is supported by a noggin of wood.

After removing the screws, the joints can usually be tapped apart with ease, particularly where rot is present. With the exception of the door rocker, reproducing the latch post and all of the adjoining timbers, only requires basic carpentry skills. However make sure the correct quality of timber is used. Always align lengths of timber along the grain and avoid knots at all costs. See the 'Timber Quality' section under The Ash Frame after selecting "Woodwork" in the main menu.


Latch Post and Elbow Rail Dimensions

Figure 4

Latch Post Dimensions

The dimensions shown in Figure 4 are based on those of my own car. As mentioned on other woodwork pages, you should make templates from your own car. However sometimes the lower latch post joint is so rotten, there is not enough left to make a decent template. If this is the case, I hope the drawing in Figure 4 is of some help. When the corresponding part on the other side of the car is intact, you can obviously use it to make a template.

Re-assembling the Latch Post and Elbow Rail

When you are satisfied you have produced accurate parts, assemble them with screws only and ensure all the joints are tight and everything is perfectly aligned. Pre-drill joints with pilot holes to prevent the wood from splitting. Putting screws in at a slight angle will help prevent them from coming loose and produce strong joints. When everything fits together perfectly, use a good quality urea-formaldehyde glue and stainless steel screws to finally assemble the new parts of the frame. Allow 24 hours for the glue to set before disturbing it. Treat the end grain of the timber with a fungicidal product and bed new panels onto the frame with a good quality waterproof mastic. Finally prime and paint the timber with high quality exterior paint.