The MG T-Series ash frame

Wood tub, steel chassis

First, a common misunderstanding. The T-Series chassis is a conventional steel ladder frame; it is the body tub that is built on wood. The tub is a skeleton of ash, assembled at the factory over a jig, then skinned in steel panels that are tacked and folded over the timber and, in a few places, welded. That wooden tub is bolted down to the steel chassis through metal brackets, the body irons. So the wood is structural, holding the shape of the body and carrying the doors, but it is not the chassis. Because the panels are formed over the frame with barely a flat surface anywhere, wood and steel are married together in a way that makes any later repair painstaking.

Why it rots

These are open cars, and for most of their lives the top has been down, often in the rain. Water finds its way into the ash through every seam, and once it is in, it stays. The wood swells, softens and begins to part company with the steel skin, and as it goes the whole tub loosens and flexes, working itself apart with every mile and adding the squeaks and rattles that T-Type owners know well. On a T-Series it is rot, not rust, that is the defining structural problem, and a car left standing outside can need fresh timber alarmingly quickly.

Where it rots

The rot follows the water, and it concentrates in a few predictable places.

• The main side rails, the large ash beams running down each side of the tub beneath the doors: the primary structure, visible from underneath where the running boards bolt to them.
• The hinge pillar and the latch pillar, the uprights spliced into the main rail at the front and rear of each door to carry the hinges and the door catch. The wood just below the A-post and B-post is exposed and is very often the first to go.
• The doors themselves, which are wood-framed too; behind almost any door skin there is timber that can be soft.
• The rear tank area: the wood around and ahead of the fuel tank at the rear.
• The sills and joints, where the uprights meet the lower rails, and the firewall and dashboard wood glimpsed from inside.

How to inspect it before you buy

Much of the ash is hidden behind steel, so an inspection is always partial, but there is a lot you can learn without dismantling anything.

• Get underneath and probe the main side rails and the hinge and latch pillars with a screwdriver or a bradawl. Sound ash is hard; if the point sinks in, the wood is going.
• Take each door at the top of the hinge and push and pull it up and down. There should be barely any movement.
• Push and pull at the top of the door aperture; it should feel solid, not flexing.
• Open and close the doors. Doors that have dropped, or no longer shut cleanly, are the classic first sign of a tired frame.
• Look under the dashboard at whatever wood is visible, and watch for latch and striker screws that have egged out their holes, a sign the wood behind them has softened.

One honest warning: if you find rot while poking around from underneath, it is almost always worse than it looks, because the worst of it hides behind the panels. A car whose doors sag and whose rails are soft needs serious woodwork, and that should be reflected in the price.

Repair, from a soft spot to a full re-frame

Repair runs across a wide spectrum. At the mild end, a localised patch of dry rot can be stabilised with a penetrating epoxy consolidant of the kind used on wooden boats, which soaks in and hardens; that is a legitimate fix for a small, sound-but-soft area, and the same products are used to firm up old timbers so they can serve as patterns. Beyond that, the honest answer is that soft structural wood has to be replaced. Timber kits for the TC, TD and TF are available, but they come oversized and roughly shaped: every piece must be hand-fitted, its mortices and angles adjusted, and the steel skin peeled back to reach the wood and folded down again afterwards. At the far end is a full re-frame: the tub lifted off the chassis, the panels removed, and the entire ash skeleton rebuilt, ideally on a jig or using the old frame as a pattern so that everything stays aligned and the doors still fit at the end. This is specialist joinery as much as car restoration, exacting and slow, and after the engine it is often the largest single cost in a T-Series restoration, a complete timber set running to several thousand pounds before any labour. Standard restoration references such as Mike Sherrell's books walk through the process in detail.

What it means when you are buying

Because the frame is so central and so costly to put right, it should shape what you pay. A car with a sound, tight tub, doors that shut with reassuring precision and rails that ring hard under a probe, is worth a premium. A car with soft rails, sagging doors and egged-out screws is a woodworking project whatever else is done to it, and either the price should reflect that or you should walk on to a better car. For the wider inspection, see the buying guide.

Read next

The coachbuilt models: MG TC, MG TD and MG TF. See also the buying guide, restoration planning, and identifying a genuine TF 1500. Corrections and additions from owners are welcome.