Triumph TR4A Spotter's Guide
Key features at a glance
This is an attempt to help differentiate the TR4A from the TR4 at a glance. It concentrates on US models; according to the photos in Bill Piggott's Original Triumph TR , the UK model differ in some small details (notably front turn signals).
- Exterior: The most notable differences are the grille, which is an aluminum extrusion instead of a stamping, and the turn signal repeaters and parking lights, mounted on the fenders with chrome trim strips along the beltline of the car. The main turn signals are much larger (always white lenses). Bumper overriders have moved outboard, between main headlamps and turn signals. Bonnet is badged with smooth "TRIUMPH" lettering and the old Triumph Globe insignia. The bonnet bulge continues the later TR4 pattern, going the full length back to the opening edge. Lucas "tripod" lamps are not correct, even though they look quite lovely.
The TR4A continues the use of 4-1/2J (15x4.5 inch) pressed steel road wheels, chromed nave plate and globe medallions. Piggott (and others) claims that these wheels are always painted silver, but I have evidence that some wheels in the US were painted Spa White . 60-spoke wire wheels (painted aluminum or silver, or dull or bright chrome) were offered as an option, with a chromed two-eared knock-off nut. "Silverstone" 15x5 alloy wheels were a competition option, both in magnesium and aluminum alloys.
The TR4A was introduced with crossply tires (5.50/5.90.15) as standard, but it seems that most cars were deliverd on radials, usually Michelin X, in 165-15 size.
It seems that the factory didn't fit external mirrors. Most US Triumph dealers attached one or two "bullet" mirrors to the doors.
From the windscreen back, the TR4A looks essentially identical to the TR4. The top doesn't disappear under the interior trim any more. The Surrey top is a desirable option; as far as I know, the factory never offered a hardtop, though there were aftermarket units available.
The taillight lenses are still all red, and the boot lid on IRS cars has an extra "IRS" badge. The exhaust was either twin silencers or a single large silencer mounted transversely with dual exhaust pipes. Reversing lights were a rare option, consisting of a pair of chromed housings mounted at either end of the bumper by the outboard bumper mounting bolts.
- Interior: dashboard in walnut veneer laminated on plywood; gauges have flat lenses with chrome trim and partially shrouded needles. Tachometer is on the left. Handbrake is mounted centrally on the transmission tunnel. The TR4A got two-speed windshield wipers, operated by a pull-out switch.
Unlike the TR4, the TR4A has trimmed door tops - a glued-on panel that matches the interior trim color. Only one style of seat was offered throughout the TR4A's lifetime, with plastic piping and straight seams on the inserts.
- Engine: carburetters varied over the lifetime between SU HS6 and Stromberg CD 175. The flame trap air cleaner arrangment seen on the TR4 is gone; most sources seem to agree that oval air cleaners are proper. There's a large PCV valve that is plumbed between the chromed rocker cover and the intake manifold. The oil filler cap is not vented. Exhaust manifold is cast iron with two exit pipes (about the same configuration as the competition mild-steel header, but heavier).
The radiator is wide with an integral header tank and a plastic overflow/recovery tank mounted on the manifold-side fender. There is no hole for a starter crank, even though the grille retains such a hole.
Numbering of Major Components
- Engine: engine numbers for the TR4 and TR4A have a 'CT' prefix and an 'E' suffix. Factory rebuilt engines have an 'FRE' suffix. Engines prefixed 'CTA' indicate that they have 83mm liners (1991 cc). This was not a factory option for the TR4A.
- Commission Number: Marked on a plate rivetted to the bulkhead on the spark plug side, the TR4A is prefixed 'CTC', with the lowest number being CTC50001. Rigid rear US cars still had the prefix 'CT' but were numbered in sequence with the 'CTC' cars. Some cars were exported from Coventry as kits for local assembly: an 'ICTC' prefix indicates that the car was built in Belgium. A suffix of 'L' indicates left-hand drive, and a suffix of 'O' indicates the overdrive option.
This plate should also indicate the original paint color and interior trim style (leather or Vinyde) and color.
- Body: Body number is recorded on a stamped aluminum plate on the opposite bulkhead, and has the suffix 'CT'.
After 25-35 years, it would not be a surprise to come across a TR4A with major components whose numbers do not match the listings above. Gearbox and differential swaps are common; we have even seen one car with TR4A body panels mounted on a TR4 frame. Much of the above information was taken from Bill Piggott's Original Triumph TR .