When the Triumph GT6 arrived in 1966 there wasn’t anything else like it for the price. With its six-cylinder engine, compact dimensions and hatchback configuration it was fast, usable and stylish – and affordable too.
Now the GT6 is firmly into the realms of being a classic it’s just as appealing because it’s still got all of those traits that made it so desirable in the first place, but it’s also brilliantly served by clubs and specialists.
Your AutoClassics Triumph TR6 inspection checklist
In period the GT6 gained a reputation for being a handful to drive thanks to its swing-axle rear suspension (with double wishbones up front). Later cars got a different design which helped to tame things a bit, but the reality is that unless you’re driving at full tilt everywhere you won’t notice these shortcomings. Especially if you invest in one or two suspension mods.
Engine
All GT6s came with a 2.0-litre straight-six that’s renowned for being torquey and smooth. Unfortunately it’s also notorious for its oil leaks and its death rattle on start up; the latter is because Triumph didn’t fit an oil filter with a non-return valve, so the bearings are starved of lubricant when the engine is started. Spin-on oil filter conversions are readily available though; they’re cheap and easily fitted.
Changing the oil every 6000 miles is a good idea and if this regime has been adhered to a GT6 engine will rack up 100,000 miles or more. When a rebuild is due the parts are readily available and the engine’s simplicity means DIY rebuilds are straightforward enough – just ensure that all of the oil seals are replaced as a matter of course.
Gearbox
The GT6’s gearbox will give 100,000 miles’ use between rebuilds, with wear given away by pronounced whining. More likely to be giving problems, especially if the car has been driven hard, is a tired differential. These will last 100,000 miles if the oil is changed occasionally, but it often isn’t.
The propshaft and driveshafts are fitted with universal joints and these wear out leading to clonks as the drive is taken up. They’re not costly or difficult to replace though. The plastic bushes wear in the remote gearchange mechanism, but again, they’re easily and cheaply replaced.
Overdrive was always optional on the GT6. It’s become a popular conversion but bear in mind that cars with it got a 3.27:1 differential while those without got a 3.89:1 unit. As a result there’s no difference between the cruising abilities of cars with and without, but you get some extra intermediate gears if you have it, so it’s well worth having.
It’s possible to fit overdrive if the car doesn’t have it already, but it means sourcing an overdrive gearbox and getting a shorter propshaft made; you can’t just fit an overdrive unit to a non-overdrive gearbox. If overdrive is already fitted but it’s not working properly, check the electrical connections and make sure there’s enough oil in the gearbox.
Some GT6 Mk3s were fitted with rotoflex couplings. The best items to fit are genuine Metalastik and these will last about 35,000 miles; cheaper alternatives tend not to last as long.
Suspension and brakes
The double-wishbone suspension up front uses trunnions with vertical links, and these wear if not occasionally lubricated with EP90 gear oil, leading to the suspension collapsing. The drop links that connect the anti-roll bar to the wishbones can also break, but these are cheap and easy to replace.
The independent rear suspension features a transverse leaf spring, which sags with age. Replacements are available but without a proper spring lifter it’s an awkward job. The swing spring that’s fitted to late Mk3s has rubber pads between the leaves and these perish, reducing refinement and increasing wear rates.
Bodywork
The GT6 consists of three key sections: the chassis, bonnet/wings and the body tub, which is made up of the roof, rear wings and floorpans. The chassis is what gives the GT6 its strength so it’s essential that you check for corrosion by getting the car onto a ramp. Replacing a chassis is possible but that means removing and refitting all of the running gear. New chassis aren’t available but used ones are if you look hard enough.
Most GT6s have had some bodywork repairs by now. Localised repairs shouldn’t pose any problems but if the car has been completely restored the bodyshell and chassis must be separated. If this hasn’t been done it hasn’t had a full restoration, and if it has been done you need to check all of the shut lines very closely. Similarly, properly repairing significant chassis rot requires bodyshell removal.
The sills also give the GT6 some strength and these are rot-prone, just like the door bottoms, the boot floor and the wheelarches. The tailgate aperture also rusts, the bulkhead does too if brake fluid has been allowed to spill onto it, and the leading edge of the roof may be showing evidence of corrosion.
Crash damage is another possibility so look at the front chassis rail that runs across the nose; also look at the main rails on either side of the engine. They should be straight; any rippling or kinks will be obvious.
Interior
The interior trim may have seen better days but that’s no problem as it’s all available new, with everything made to a high standard. It’s competitively priced too, although if you need everything (seat covers, carpets, trim panels) the cost will soon add up.
The electrical system isn’t complicated and it doesn’t usually give many problems. If there are any glitches it’s probably because one of the bullet connectors within the loom is failing to make contact. New looms are available if things are really bad.
History: Triumph GT6
- 1966: The GT6 debuts at the Earl’s Court motor show. Overdrive is optional while the bumpers and lighting are carried over from the Spitfire.
- 1968: The GT6 Mk2 arrives with a new dashboard, revised cylinder head and tweaked rear suspension. The straight-six’s top end is from the TR5, to breathe more easily, while the rear suspension adopts rotoflex couplings and wishbones in the rear suspension. Styling adjustments include the removal of the louvres in the side of the bonnet, raised bumpers front and rear and Rostyle wheel trims.
- 1969: Minor revisions bring better interior padding and an improved steering wheel, and the structure is strengthened to cope with tougher US crash regulations.
- 1970: The GT6 Mk3 goes on sale with a deseamed bonnet and the rear panels are updated.
- 1973: A brake servo is fitted, the rear brakes are increased in size and the rotoflex couplings are swapped for a swing-spring rear axle. The instruments are revised, vinyl replaces the brushed nylon seat covers. And head restraints plus tinted glass are fitted for the first time.
PetroFacts: Triumph GT6
GT6s aren’t all that common and with word having got out about how easy these small Triumphs are to drive, and how much fun they are, values have risen sharply in recent years, especially for the Mk1 and Mk2.
The Mk3 is the most common of the lot but there were two versions. While early cars got rotoflex suspension, this was later ditched to cut costs. It’s debatable whether or not it’s worth having as it adds complexity (the rubber couplings don’t last forever) and it doesn’t add much to the driving experience.
The earlier cars have the most charm while the later ones are cheaper and easier to find. Whatever you buy it’s worth trying to find one with a full-length sliding cloth sunroof as the cabin can get pretty warm if ambient temperatures are high.
There are GT6s around with 2.5-litre engines and some have been mated with Spitfires to create a GT6 convertible. If done well these produce a very usable classic that’s great fun to drive – as long as the work has been done properly.
Prices: Triumph GT6
- Project!£1500-2500
- Good!£4000-10000
- Concours!£8000-16,000
- Most expensive at auction £15,400 (1871 MkIII)
