Tip no.1 - Gluing wood

It is strongly recommended that animal glue is not used, even for the sake of originality. When the car rots away again, it will end up less original! Most PVA adhesives (although there are various types) are also not suitable. The ideal type of adhesive is resorcinol formaldehyde, a two part formula, resin and hardener. Often recommended (and used for boats and gliders) is the brand still commonly known as Aerodux (as produced by Cyber Geigy in the past). It is now part of the Prefere™ range of adhesives (by Dynea). It has very high water resistance to WBP (Weather and Boil Proof) grade. It is also good at filling gaps if a joint is not a perfect fit, without much loss of strength. It is less suited for repairing trim, because of its dark colour.

Tip no.2 - Choice of wood screws

Screws need to be driven into wood frame joints very tightly. Therefore slotted heads are preferred, and the material should be either mild steel (possibly zinc-plated for rust resistance) or stainless steel. Aluminium and brass screws are not strong enough.

Tip no.3 - Inclination of wood screws

Wood frame joints are fairly crude but effective. Joints are pulled up tightly by the angle of the screws. For halving joints, the screws are not quite square to the plain of the joint, which allows them to slide the two pieces of wood - during tightening - until any gaps are closed up.

Tip no.4 - Removing rusty wood screws

If you are lucky, many screws will undo with a screwdriver! An impact screwdriver might help on large screws that are only slightly rusted, but care needs to be taken not to either break the screw, or destroy the wooden thread. More badly rusted screws will need to have their heads drilled off. This is awkward when a component is held by screws that are at various angles (maybe at right-angles to each other). In such a case, some screws may have to be fully drilled out. If you are lucky, you may be able to get pliers onto the screw head to undo it.

The worst screws will have rusted to almost nothing just under the head, while the thread has gained a large ball of rust debris, locking the screw in place. It will have to be fully drilled out. Damaged screw holes can be filled up with home-made ash dowels, and then new pilot holes drilled into them.

The rear wings are secured by large wood screws. One option is to force the aluminium washers off the heads (they can be straightened out again), and then pliers can be used to remove the screws.

Tip no.5 - Timber

It is important to use only the best quality timber, although I confess to be no expert on this subject. Air seasoned English ash is rated as the most suitable, along with American white ash. AC (like many manufacturers) also used beech and even some mahogany. You will probably find a mixture of the three timbers on your car. However, ash is the first choice. There is little to choose between various hardwoods for strength, but ash has additional properties of value, such as always springing back to its original shape after being heavily loaded.

For plywood, there are two considerations: The timber, and the adhesive. The latter is where the AC was seriously lacking. You need to look out for WBP grade adhesive in plywood (Weather and Boil Proof). The timber should be birch throughout. Note that some birch plywoods only have the outer plies (or alternate plies) of birch and rest of softwood.

Tip no.6 - Joining boards end-grain to end-grain

End grain to end grain joints will be stronger if they run diagonally across the boards. Door steps and sill-boards tend to rot away from one corner, so this is convenient anyway.

Tip no.6 - Joining rails to the edge of plywood

Most of the plywood panels have a number of hardwood rails attached to their edges, by driving a screw into the board parallel with its plane. This tends to split the plies. A more upmarket solution used in coach-building, was to embed a short length of dowel in the plywood, at right-angles to both the board itself, and the screw to be inserted. A tapping hole would then be drilled through the dowel, and a clearance hole through the plywood. A less elaborate alternative, is to firmly clamp the plywood while drilling the tapping hole, and also while driving the screw in.

Tip no.7 - To paint, or not to paint

Wood frames of coachbuilt cars were generally not painted for protection. Welding up of panelling on the frame might have had some influence on the lack of paint used. Maybe the top coats or primers available were not considered ideal? In later years, Morgan painted their frames, and I consider it advisable to do so for longevity of a restored car (especially to keep woodworm away!). It is important to use a paint that allows the wood to "breath", as humidity changes. Marine paints that seal the wood should NOT be used for a car. A good quality synthetic enamel will do the job for the top coats. The ideal primer is the aluminium based type, which can cope with various wood painting challenges, including old wood that was creosoted (such as the AC's floor panels).

Morgan practise has been to paint the frame black, but I prefer something lighter. This is partly to make it easier to see and clean from under the car, and also because the woodwork in the boot will be flock-sprayed a light brown on my own AC. Panel squeak is a potential problem, with the bodyshell resting upon a glossy paint finish. I intend to lubricate the appropriate areas with wax polish. The shell touches the wood frame around the window openings, and at the top of the boot area. The roof framework already has strips of padding to prevent rubbing. Silicone rubber sealant may also help to reduce squeaks and keep rain water out, if applied under the panel edges.

Tip no.8 - Protecting screws and bolts

The wood screws and the bolts that pass through the wood frame, will rust very quickly unless they are protected or use is made of stainless steel. Mineral oil/grease should not be used, because this will speed up rotting of the wood. Some restorers seal in the fasteners with epoxy adhesive. Another solution is to coat the screws, coachbolts, etc. with Waxoyl. Credit for this tip goes to Alan Alderwick, author of "How to Restore Wooden Body Framing" (Osprey - 1984).

Tip no.9 - Nuts and bolts

Never mix nuts and bolts that have different threadforms, even if they appear to fit (and even if some merchants recommend it - sheesh!). So, DO NOT mix UNC and BSW, or BSF and BSCy, even though some sizes appear to fit (similar general dimensions).

Also, NEVER cut a thread with a die - at least not on anything remotely important, which covers most of a car. A thread cut this way will lack any kind of run-out or stress relief groove, etc, at the end of the thread, and so increases the risk of fracture. The thread itself will also be poor quality. The best external threads are rolled ones, because the 'grain' of the metal flows along the roots and crests of the thread.

Don't replace high-tensile bolts with stainless steel, even if the ultimate strength of the stainless steel appears to be high enough. The effective yield strength of stainless is relatively low. If replacing mild steel fasteners with stainless steel, avoid contact with aluminium components, otherwise corrosion will be accelerated.

Tip no.10 - Screw head recess

It is important that screw heads cannot touch the inside of body panels, so the holes should be countersunk deeply (possibly using a small diameter countersink).

Tip no.11 - Panels creasing over the wood frame

The body panelling should not touch the edges of the wood frame components, except where the panel edges are fastened on. Otherwise the panelling may crease slightly, which will show up on shiny paintwork. This is why some faces of wooden parts are at a slight angle to the panelling that covers them. There are a few exceptions to this rule, where the bodyshell does rest upon the top surface of some wood frame parts, and these parts should have their edges rounded off (if they are not rounded by design already). The roof frame also has strips of waxed card for the roof panelling to rest upon.

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