Mods and Consequences

Triumph TR4 & TR4A

The Triumph TR4 looked thoroughly modern when it was unveiled at the 1961 Earls Court Motor Show, but there was little more than a tweaked TR3A underneath that sharp Italian suit – a car not dissimilar to the original TR2 of 1953. This means that while the TR4 celebrates its 58th birthday this year, the running gear was first seen 65 years ago. Which makes it all the more incredible that the TR4 doesn’t feel particularly vintage to drive. However, while the TR4 doesn’t give its age away as readily as you might think, there are all sorts of ways in which you can make improvements, whether the focus is on comfort, reliability, performance, safety or handling.

TR values have increased significantly in recent years, so big changes, like an engine swap, aren’t a good idea. As a result, you’re better off using traditional tuning methods, such as fitting bigger carbs, matching the inlet manifold, porting and polishing the cylinder head and fitting a freerflowing exhaust.

TR guru, Gary Bates, says: ‘The key is not to get carried away, which many owners do. They raise the compression too much, fit Webers and a scary camshaft, then they end up with an engine that doesn’t get going until 3500rpm or more. The best thing you can do is fit a big piston kit; it’s a set of 89mm liners and pistons that takes the displacement to about 2.3 litres. Very well made and priced at £3000 for the parts or £4200-plus fitted, it makes the TR’s torquey engine even more muscular.

‘When it comes to carburation, stick with SUs rather than Strombergs as they’re easier to tune; Webers are overkill for a road car. A Piper Yellow cam is ideal for road use and with some careful gas-flowing – done professionally – you can get a reliable 130bhp at the flywheel if you also fit better air filters and the right exhaust. I’d recommend a single-bore system. It’s not just about power though; the correct suite of changes will realise 160lb ft with a nice flat torque curve.’

Most of these cars have overdrive, but some, especially US cars, don’t. Budget £1500 to convert your car yourself; TRGB charges £3000 to do the whole thing. You don’t need to change the propshaft. Don’t try to fit a saloon gearbox as the speedo calibration and drive are wrong, as are the mountings.

fIT a sTaInlEsss EXHausT A stainless steel exhaust is fit-and-forget. Most TR4 owners opt for a set of Phoenix pipes as the build quality and sound are spot on. Extractor manifolds need fettling to make them fit, along with the retaining butterflies. CHoosE your dampErs Gary advises sticking with lever arm dampers on the TR4, but using telescopics, which last longer and can be adjustable on the TR4A. Don’t use polyurethane bushes in a TR4A diff – they transmit too much vibration through the bodyshell. fIT a BraKE sErVo The TR4/TR4A never had a brake servo, but it’s worth fitting one to reduce pedal pressure. There’s no need to upgrade the calipers or discs, but a servo in conjunction with harder pads will make the brakes feel much more reassuring. usE ElECTronIC IGnITIon Most classics benefit from electronic ignition, but Gary doesn’t like units that fit inside the distributor as they can overheat. His preference is for a Lumenition unit in a separate aluminium box fitted to the inner wing. ConVErT THE oIl fIlTEr The standard oil filter lacks a non-return valve, which means the big-end bearings are starved of oil when the engine is started. A spin-on conversion costs around £60 – and why not fit an oil cooler while you’re at it? upGradE THE sTarTEr The original Lucas starter motors take a bit to work, so it’s worth fitting a modern hi-torque unit. Gary recommends a Wasp unit. You’ll have to fit one of these if you fit an extractor manifold, as they’re the only ones compact enough to fit. sWITCH To an alTErnaTor £210-£550 £300 £350 £185 £60 £215 £50+ You can fit an alternator that looks like a dynamo for around £350, or you could fit an alternator for a fraction of the cost. Fit a conversion kit and you can stick with the original belt rather than having to fit a narrower one.