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Triumph GT6 buying guide

Triumph GT6 As soon as the Triumph GT6 hit the scene in 1966 it was christened the poor man’s Jaguar E-type, and for good reason. With a smooth straight-six nestling under a long bonnet (which like the Jag’s was the whole front end of the car), there was no shortage of go or refinement. Nearly 40 years later not much has changed, although things like parts availability and ease of restoration are now more important, and once again, the Triumph scores highly.

Triumph’s initial plan had been to use Spitfire mechanicals in a hatchback body and name it the Spitfire GT. But once the extra weight of an enclosed body had been taken into account, it soon became clear that the Spitfire’s 1147cc four-cylinder unit would have struggled to offer a decent drive. So a bigger engine was called for, and after the 1596cc Vitesse powerplant was rejected, the later Vitesse’s 1998cc straight-six was used instead. Because of this change of direction for the project, the planned 1964 launch turned into a 1966 debut, at the Earl’s Court motor show. By then the Herald had spawned the Vitesse and Spitfire, making the GT6 the last of a quartet.

It’s now 35 years since the last GT6 was built, and the cars are just as much fun now as they were back then – but even more affordable. Any GT6 with an MoT is worth at least £1500 – even a restoration project is worth no less than half that. There’s little difference in values between the different versions, although the Mk3 is slightly more desirable. The best show-winning cars will fetch £9000 while a really superb example is worth closer to £7000. A decent car that needs no work but won’t win any prizes either costs around £3000 to buy.

Any engine problems?

The Triumph straight-six engine is renowned for its smoothness as well as its low-down torque. It’s also famed for its oil leaks, and rattles at start up. But thankfully these ‘characteristics’ can be engineered out without too much difficulty or expense. If looked after with oil changes every 6000 miles it’ll last 100,000 miles between rebuilds.

All parts are readily available, and it’s an easy engine to cut your teeth on if you’re buying a restoration project. Renew all oil seals while you have it apart, as it will save taking the engine out again later. If the engine has had it and you don’t fancy rebuilding it yourself, a running unit can be picked up for around £100 – although you’ll need to pay twice that for a really good example.

If the original canister type of oil filter is still fitted it’s worth investing £40 on a spin-on conversion. That will allow you to fit a modern filter with a non-return valve on it, meaning the bearings won’t be starved of oil when you start it up, eliminating that start up rattle.

How about the Triumph GT6 transmission?

The GT6’s weakest link is its final drive, although if it’s well looked after there’s no reason for it to leave you stranded. The problem lies with the universal joints and diff, which can struggle to cope with the 2.0-litre engine’s torque. They’re an evolution of the Herald units – which in turn had evolved from Standard units of years before. The first Heralds had generated less than 40bhp and all GT6s put out more than double that, so if an owner has been over-enthusiastic with the thottle there may be rather more play in the system than there should be. Make sure the diff and gearbox aren’t especially noisy – the gearbox is usually sturdy, but the diff will whine loudly if it’s getting tired.

If there’s clonking from the transmission as you manouevre backwards and forwards it’s probably because some of the universal joints need replacing. New joints are only £10 apiece, and replacing them isn’t tricky, but you might have to do all four if things are really bad.
The plastic bushes in the remote gearchange mechanism wear out eventually, but fitting a new set is cheap and easy – expect to pay around £20 for a pack. No GT6 had overdrive fitted as standard, but it was available as a factory-fitted option. Few Mk1 owners ticked the box but it became increasingly popular and most Mk3s owners specified it. A lot of cars have it nowadays because it’s easy enough to retro-fit – and overdrive is worthwhile because it’s more relaxed driving a car equipped with it if you raise the final drive ratio at the same time. Unusually, when new a GT6 with overdrive was no more relaxing to drive than one without.

That’s because the final drive ratio of cars not equipped with overdrive was lowered to 3.27:1 from the previous 3.89:1, to improve acceleration rather than make high-speed cruising more relaxed. If overdrive is fitted but it’s not working, the chances are that it’s only an electrical connection somewhere that’s playing up or a lack of oil pressure because the unit’s internal filter needs a clean. If it’s anything more serious, rebuilds are best left to a specialist, but if it has called it a day you can buy a rebuilt overdrive for £150 on an exchange basis.

If the car is fitted with a rubber doughnut Rotoflex coupling, make sure the coupling isn’t about to disintegrate. Even the genuine Metalastik couplings last no more than 35,000 miles and cost at least £40 each side. If the car doesn’t have Rotoflex couplings things are a lot simpler as you’ve then only got to be concerned with the rear bearings which last well and cost £18 per side.

Suspension, steering and brakes

The main thing to check with the rear suspension is the condition of the transverse leaf spring, which sags with age. Replacing it isn’t especially pricey at around £100 (£80 for Rotoflex) but it can be a devil of a job unless you’ve got a spring lifter to help you. If you have the swing spring (late Mk3) it will probably only need new rubber pads between the leaves. There’s also a rubber bush at each end of the leaf spring along with bushes in the radius arms which locate the back axle and in each of the dampers. By the time the damper rubbers have gone the damper itself is likely to need replacing, which will set you back £32 for a pair.

Thankfully the front suspension doesn’t give many problems. Sometimes the drop links that hold the anti-roll bar to the lower wishbone can break off, but these are available at £16 a pair. Tired springs or dampers might need to be replaced, but the job is easy and the costs are low at £47 and £32 respectively for a pair of each. The wishbones are fitted with rubber bushes, as are the anti-roll bar mounts and the steering rack mountings. These can all be replaced with polyurethane items and while you’re checking to see if they’ve perished have a look at the ball joint at the top of the vertical link, to make sure it hasn’t got a lot of play in it.

Although the Herald family of cars has a reputation for suffering from irritable trunnion syndrome, it’s only if the car has been neglected that you’re likely to have problems. If they’ve been lubricated as specified in the owner’s manual, they’ll be fine. But few owners know that every 6000 miles EP90 is supposed to be pumped in (not grease). The trunnions themselves are brass and don’t give problems – it’s the cast iron vertical link which threads into the trunnion which breaks. Replacement links cost £94 apiece and the easiest way of checking to see if they’re about to give is by seeing how heavy the steering is. It shouldn’t be especially heavy even with the weight of the straight-six sitting over the front wheels.
Pressed steel wheels were fitted to all GT6s as standard, but by now many have been swapped for alloys or wires. Because the GT6 has an unusual offset it’s easy to buy wheels that suffer from clearance problems, so check that they’re not rubbing if aftermarket wheels are fitted. If wire wheels have been put on, make sure that the spokes haven’t broken and that the splines haven’t worn. The widest tyres that will comfortably fit a GT6 are 175s.

Bodywork, electrics and trim

It’s a full three decades since the last GT6 was built, so unless the example you’re looking at has been really cherished, it will have had some remedial work performed on it at some point. That’s no problem if it’s been done properly, but if a full-scale restoration has been attempted, and the body and chassis haven’t been separated, the work clearly hasn’t been done properly. It’s not so much the bodyshell that’s the problem as the chassis. The rear can be easily repaired, but ensure the front is aligned properly. The bonnet mountings (which are available new) are the most important here, because if they’re not lined up correctly you’ll never get the bonnet to line up properly.

The bodywork itself consists of two main sections: the front end (bonnet top, nose and front wings) and the main bodyshell (a tub made of the roof, floorpans and rear wings). The tailgate and doors attach to the tub and it’s all put together like an overgrown Meccano kit – handy for taking apart and putting back together.

Although it’s a good idea buying a bodyshell that’s not full of holes, it’s the chassis that gives the GT6 most of its strength. Thanks to the engine having a tendency to spray the underside of the car with oil, there’s a good chance that the metal has been reasonably well preserved towards the front. It’s worth buying replacement outriggers to patch up the chassis if the main rails are sound, but if the frame has rusted away comprehensively you’ll be better off getting a replacement – you won’t find a new one anywhere, but usable second hand ones can be picked up readily for £100 or so. But bear in mind that everything is based around the chassis, so if it needs replacing you’re going to have to remove the brakes, steering, suspension and bodywork.

Even if the chassis doesn’t need any work, there’s a good chance the bodywork will. The first areas to check are the sills, floors and wheelarches. The GT6’s sills are structural and if they along with the floorpans haven’t been replaced yet, the chances are they will need renewing before long. Nearly all panels are available new and are fairly easy to fit, but if somebody else has already done this, make sure the panels line up – putting else somebody else’s bodge is far harder than starting from scratch. 

Check under the false boot floor where the metal floor meets the arch – the passenger side is hidden under the petrol tank but the off-side will give a good idea of condition. All versions have a habit of corroding between the rear lights, and as new panels are not available you’ll have to be handy with the MIG. Doors are rot-prone but thankfully the shells usually remain sound needing only a new skin.

Other rot spots include the bottom of the hatch aperture which fills with water then rots out and the double-skinned leading edge of the roof where it meets the windscreen surround – condensation collects in the seam and rots from the inside out. As 
if all this wasn’t enough, it’s quite common for the master cylinders on the bulkhead to leak brake fluid  onto the metal panels below. Once this has stripped the paint, corrosion will follow, but the use of a silicone based brake fluid will avoid this.

Even if there’s no discernible rust anywhere, the car may have been in an impact at some point. Poor shutlines are common on otherwise well-restored GT6s because aligning the panels can be very tricky. The easiest way of telling if the car has been shunted is to look at the chassis rails in front of the engine, which may be crumpled. Even if the car has been in a fairly big accident, if the chassis has been replaced properly along with the necessary panelwork, there’s no need to worry. That’s the beauty of not using a monocoque – although if you do need to replace the bonnet, you’d better have at least £600 handy.

If the wiring has been hacked about you can buy a new loom for £170 and the few ancillaries that are fitted, such as wiper motor, dynamo/alternator and starter motor are cheap to buy.
If you find a GT6 with a completely trashed interior but it’s on offer at a knock-down price, you’re in luck as it’s possible to buy new carpets (£130), door panels (£50/pr) and seat covers (£140) from Newton Commercial (01728 832 880). As far as exterior trim is concerned, Mick Dolphin is a good source.

Should you buy one?

With low parts prices, strong spares availability and the car’s Meccano-like construction, even the tattiest GT6 can be revived – as long as you’ve got the patience. Even better is the fact that once built, the GT6 is great fun to drive – and it’s even more fun if you mate a Spitfire with a GT6 to produce the 
drop-top that Triumph should have built.


1966: GT6 debuts at Earl’s Court motor show, with 95bhp 1998cc Vitesse engine. Overdrive was optional while bumpers and lighting are carried over from the Spitfire.

1968: The Mk2 GT6 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: Better interior padding and an improved steering wheel, and the structure is strengthened to cope with tougher US crash regulations.

1970: The Mk3 GT6 goes on sale little changed from its predecessor. Deseamed shark-nosed bonnet and the rear panels are updated with the family cut-away tail which incorporates less chrome. There are no significant changes under the skin.

1973: A brake servo is fitted, the rear brakes are increased in size and the rear suspension’s Rotoflex couplings disappear, with the swing-spring rear axle later to be used on the Spitfire being fitted instead. Vinyl replaces the brushed nylon seat covers and head restraints plus tinted glass are fitted.
Triumph GT6
Last updated: 3rd Dec 2014
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  • Lot 141

    Triumph GT6

    £6,500 - £8,500 est. £6,500 - £8,500 est.

    Triumph GT6

    The Warwickshire Exhibition Centre
    Auction Date: 05 Dec 2015
    Last update: 10 Days Old

    • Mileage: 101050 mi

    • Engine size: 2

    Auction Date: 05 Dec 2015
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