Triumph TR3 drawing


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Where rust hides on a Triumph TR3


One of the first questions that comes to people's minds when they contemplate purchasing or restoring a TR2 through TR3B is where do they tend to rust. The good news is that many body panels are being reproduced. The bad news is that the factory assembled the body before they painted the car and a lot of them have spent a lot of time sitting out in the rain.



The frame is extremely strong and does not have any areas prone to rust.


Front valence

Since the car was assembled before painting, coverage on the inside of the valance may not as good as on the outside. You would need to remove the grill and check the inside of the valance with a mirror. My TR3's front valance had no rust on the outside but a coating of surface rust on the inside. Mud can build up on the inside lower lip of the front valance allowing moisture to sit under the grill. This can be visually inspected by looking underneath with a flashlight.


Front wing attachment area

The front outer wing is bolted to the inner wing with an overlapping horizontal joint. The metal is unpainted on the inside of this joint. There will be rust here and there may be some rust through on the outer wing at the overlap.


Lower rear front wing

There is a splash panel behind the front wheel that blocks off the space between the wing panel and the kick panel. It relies upon rubber seals for integrity.

The space behind the splash panel was not painted. My best guess is that they put a wand past the seal and sprayed a rust inhibitor.

Water and mud gets splashed up against the panel and rubber seals. When the rubber seals deteriorates, the water and mud enter into this area. Moisture takes a long time to dry in this area.

When I removed the front wings from my TR3 there was a six inch build up of wet dirt. The car had been sitting in a dry area for about four months since having been driven in the rain.

This is the single most rust prone area on the car. The companies reproducing panels recognize this and patch panels are available that replaces the bottom foot of the wing's rear section. New splash panels and rubber seals are readily available and should be kept in top condition. If you see rust bubbles on the outside of the lower front wing behind the wheel, assume it has rusted from the inside out and the lower panel will need replacing.



The floor is easily inspectable and many cars have rust through on the floor panels. The car originally came with snap fastened rubber mats that could be removed when the floor gets wet and no covering under the seat. A lot of people replaced the rubber mats with carpeting that retains water. Cars that had carpets that got wet and sat have rust problems. Luckily new reproduction panels are available and they are easily replaceable.


Petrol tank & area

This is an area prone to rust on cars that sat out in the rain. The tank is tucked into an enclosed area that has very poor air circulation. The tank sits on felt pads and is held in place with metal straps that have a felt layer between the tank and straps. Once these pads get wet, moisture sits there and causes rust on the body floor under the pads and the adjacent tank surfaces. Rust through at the points touching the felt pads is what causes almost all TR2 through 4A petrol tanks to leak. New petrol tanks are being reproduced but are very expensive.

I had my tank boiled out and patches welded over the worst rust spots on the petrol tank. I also used solid rubber pads and strips in place of the felt pads on reassembly.

A good source of rubber strips is the rubber strips that are used between the metal straps and petrol tank of an MGBGT. You can purchase this new from the companies supplying parts for MGs.

The strip of body over the tank can be poorly painted on the underside. The most rust prone spot (hardest to get to with the spray gun) in this area is over the rear wheel arches. If you see paint bubbling on the outside at that point, it's most likely rust through from the inside. This is easily fixed buy cutting out the rust through area and welding in a new patch.



The short door TR2 through TR3B have two sills on each side. An inner sill that is structural and an outer sill that is not. The inner sills hold the front of the body to the rear and maintain alignment for the door.

If you see rust bubbles on the sills, it is often the outer sills that are rusted through. Outer sills are easily replaceable by body shops and are being reproduced. When the outer sill is off carefully inspect the inner sills. If they are in poor condition they can be replaced with reproduction inner sills. This is a bit tricky and should be done by a competent body person. The door fitting, with hinges attached should be carefully checked before final welding. I had my TR3's body left on the frame so the the front & rear sections would remain stationary for this operation.


Seat frames

The seat frames were primed before being upholstered. If the car has sat out in the rain with the upholstery exposed the frames have rust. The seat backs normally just have a surface rust. The seat bottoms can be quite bad.

When inspecting a car, remove the seat bottoms and look at the seat frame bottom. These are being reproduced in metal and fiber glass. When I reassembled my seats the frames were fully painted.


Behind the instrument panel

The paint coverage may be a little thin on the underside of the scuttle (Panel the windscreen sits on). There may be surface rust there. This would be visible by looking behind the instrument panel with a flash light.


Battery box

Battery boxes tend to be heavily rusted. Battery fluids leak causing rust, and the drain can clog allowing water to puddle in the box.

Luckily the boxes are spot welded onto the bulkhead (firewall) and new boxes are readily available. For a minimum of work you can have a new battery box installed.



If a car sits in the rain, water can get into the doors and this can result in some rust through holes in the bottoms of the doors This can be observed by opening the doors and inspecting the bottom of the doors from underneath. This damage is seldom structural and you may want to retain any rust holes after derusting to serve as a drain for future water entry.


Front of rear wheel arch

The rear wheel arches are normally not a rust prone area. However if there is rust through at the front lower end of the wheel arch, the interior of the inner sill will be exposed to moisture.


Boot floor

The boot relies on a gutter going around the edge of the boot opening and a seal along the inner lip of the gutter to stay dry. At each lower corner of the gutter there is a drain tube to carry away the water from the gutter.

If the tube is missing, the drain empties into the boot. If the drain is clogged, the water builds up and flows past the seal into the boot. The jute floor pad can get damp and the water will sit and rust the floor. The boot floor of pre-TS6000 TR3s has been reproduced but it is difficult to replace. Your best bet is to repair this panel. Rust through holes can be welded shut.


Rear valence

The lower rear valence is an enclosed area that is not waterproof. Rust through may occur towards the bottom of the valence. This part has been reproduced and a competent body shop can replace the valence.






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