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Do you drive this great classic or are thinking of buying one? Here’s how to ensure that you get the best out of your car for years to come

* BOTTOM END

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If the block requires a rebore then it can be taken out to 2.7-litres for more torque but the Omega pistons needed for this are dear. It’s worthwhile having the crankshaft and rods balanced however, if you have the unit in bits as it’s not an inherently high revving unit and a change of cam will mean higher revs will be utilised.

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Excessive crank end float is a well known Triumph trait; check the crank pulley movement viewing the front of the engine while an aid works the clutch. More than 0.015in play means they can drop out. Oversize types can be fitted in situ but if wear is really bad it can render the block and crank scrap. Luckily there’s plenty of good second-hand ones around but check they are serviceable or you are back to square one.

* FRONT SUSPENSION

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Uprated dampers and springs work a treat on this chassis although don’t go too hard and make ride intolerable. Poly bushing the front wishbones is said to offer good improvement. A complete tailored line of uprated suspension kits available from Revington TR, costing some £2200 depending if you want a road or race set up. Power steering from a 2000/2.5 can be fitted.

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Trunnion wear is the biggest concern and their condition is a safety issue as they can fail. Lubricant recommended is EP90 gear oil although this is hard to handle with a grease gun. Most use grease but it can cause the trunnion threads to corrode and weaken the unit. If you need to replace a trunnion it is best to swallow the cost and renew the pair at the same time.

* CHASSIS

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TR specialists D&G used to make a stiffer chassis frame specifically for road or track but a general view was that it actually upset the equilibrium and did little to tighten the handling since the inherent flexing seems to help. The stiffer frame promoted lots of added noise and creaks. Only a few are around these days but you can stiffen a standard frame if desired – speak to a specialist first – and some on sale already done.

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Around 95 per cent have been under the knife, usually to the front and rear axle locations. Outriggers most at risk and if that bad (or has been patch repaired in the past) best policy is a remanufactured chassis and most also feature beefed-up areas where inherently weak. Revington TR’s range starts at over £4000 mind although much cheaper ones (inc good used) are available from other specialists.

* TRANSMISSION

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Overdrive is always worth having as it effectively means six-speeds. Rover LT77 gearbox fits but Ford Sierra and, latterly Toyota Celica, alternatives are more popular; speak to a specialist for the best type for your needs as their ratios (and prices vary). At £3400 (from Revington TR) Ford conversion is cheaper by over £1000 but fiddlier to fit. By 1974, TR6 gear ratios aligned with those in the Stag, makes small difference.

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Intermittent overdrive operation is usually simply down to a lack of oil and/or dodgy electrical connections to the gear lever or solenoid. If you want to stick with standard overdrive (and it’s a good, sturdy system), a special Logic smart activator from TR Revington can be fitted to cut out the system on the up changes and aid flexibility plus reduces any danger of it cutting in early.

* ENGINE OUTPUT

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A tractable 180bhp can be achieved for road use via a variety head and camshaft changes and really ups the performance. Specialists warn not to get too hung up on 150bhp CP tune on the TR6 as the difference isn’t that much greater to the 125bhp unit on the road. Superior Bosch fuel pump relocated to a cooler area in the boot cures most of the original ills as does a modern metering unit.

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For long life fit a modern ‘spin-on’ oil filter to aid start up flow; top value at around £50, and use a good quality full-bodied classic oil for good pressure. Before calling in a PI expert check the basics first as poor performance can be due to nothing more serious than worn throttle linkages. Modified ones now widely available and when fitted properly instantly makes the engine perform better.

* BRAKES

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A simple swap to DBA discs with Mintex or EBC Greenstuff pads plus better hoses are ideal upgrades if they need replacing and cost under £200. Better brake callipers from Racetorations and Revington TR are the next step although they cost £1000 or over (Wilwood are cheapest bet) – perhaps not needed for most users. It’s worth noting earlier TR4 stangely featured larger discs…

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There’s no specific in-service worries but if you need to replace the rear drums, bear in mind that old (1979-83) Toyota Hilux front discs can be fitted after some mods as can Datsun 240/260Z stoppers (favoured in the US). Or fit Alfin alloy replacement drums which even at £600 a pair (from Revington TR) is usually cheaper and easier than a disc conversion and more than good enough.

* BODY AND TRIM

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All you need is readily available off the shelf from raft of TR outfits and generally, quality is better than when new. Pepper pot-style steel wheels or optional wires look right. Fitting bib spoiler to earlier cars helps stability. Dash is walnut; shinier burr or elm types cost under £200.

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TR5 bodyshells have never been made available but TR6 ones are although not from BMH (panels are though). TR Bitz used to market US-made RHD ones; now it’s left to Revington to offer handmade shells but these can cost £25-32,000 and out of reach for the majority of us!

* DIFFERENTIAL

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As with Stag, trend is now to replace diff with a modified BMW set up, that comes as a bolt on fit, to mate with existing hubs. It costs thick end of £2000 but is said to offer better ratios and durability. SC Parts has new CV units with double row bearings to cure ‘TR twitch’.

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Rust around the mounting brackets can lead to diff tearing itself away from the frame. That infamous ‘Triumph twitch’ can be greatly reduced, simply and cheaply, by fitting superior poly bushes and ensuring all the universal joints are sound before looking at other mods.

* REAR SUSPENSION

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Depends on desire and budget. The ideal solution is to ditch the antiquated lever arm dampers in favour of a telescopic conversion set up for better damping, using an adjustable Spax kit, but there are different designs so speak to a specialist first. Again, poly bushing the trailing arms, works well.

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If you’re sticking to lever arms (they can be made to work okay) ensure that they are good quality as cheap recon units don’t last. Springs prone to settle leading to a ‘nose up stance’ although it can also be due to a tired chassis frame. Ride never that good so watch you don’t over do it with the spring rate settings.

SERVICING DATA

* ENGINE OIL:  (20W/50 or 60); 8 pints

* GEARBOX:    (EP 90) 3.5 pints (including the overdrive unit)

* COOLING SYSTEM: 11 pints

* SPARK PLUGS: Champion N9Y (or equivalent) 0.025in

* C.B. POINTS: 0.014-0.016

* IGNITION TIMING: 11 degrees BTDC

* VALVE CLEARANCES: 010in (in/ex)

AND ANOTHER THING…

Cooling can be critical so consider fitting an uprated radiator if it needs renewing. Good quality electronic ignition and rolling road tune up can make standard average nick car a lot perkier. A switch to carbs is harder to achieve if racier ‘150bhp’ cam is retained. US cars similar, save engine tune and possibly lower gearing. Converting to RHD is straightforward although LHD seems to aid future resales.