1966 Triumph TR4 IRS | Classic Car Restoration

1966 Triumph TR4 IRS

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The Project

This 1966 Triumph TR4 IRS arrived at our Bishop Auckland workshop in August 2025 for a full restoration.

Updates

15th August 2025: Planned restoration works include bodywork repairs, engine, electrical, interior works and full respray.

28th November 2025: The car is currently being stripped down to identify a priority list of fabrication repairs which will be carried out. The engine will also need to be looked at, as eventually started but will need mechanical works carried out to get it running properly.

16th December 2025: The car has now been fully stripped. There is substantial corrosion to areas of the car which were hidden with filler and fibreglass which has all been removed. In this case the corrosion is so far advanced we have opted to source a replacement body tub.

> More updates to follow.

History

The Triumph TR4 was a British sports car produced by Standard-Triumph (a division of the Leyland Motors group) from 1961 to 1965, with some models registered into 1966 and early 1967. Designed by Italian stylist Giovanni Michelotti, the TR4 was a significant evolution of the earlier TR2/TR3 series.

The IRS in “TR4 IRS” refers to the Independent Rear Suspension, introduced in 1965 with the TR4A variant. This model replaced the earlier live rear axle setup with a more refined independent rear suspension system, improving ride comfort and handling. The full designation was TR4A IRS, though not all TR4As came with IRS – some lower-cost versions retained the solid rear axle, especially for certain export markets.

Key Features of the 1966 Triumph TR4 IRS:

Engine: 2.1L (2138 cc) inline-4, producing around 105 hp
Transmission: 4-speed manual (optional overdrive available)
Suspension: Independent rear suspension (IRS) with coil springs (for IRS versions)
Brakes: Front disc brakes, rear drums
Body: Steel body with aluminium bonnet and boot lid
Interior: Minimalist but sporty, with wood dash and classic Smiths gauges

Notable Innovations:

First in the TR series with roll-up windows (previous models had side curtains)
Optional Surrey Top, a hard rear window with removable centre panel (a precursor to modern T-tops)
Improved comfort and handling compared to its predecessor

Production Info:

Approx. 28,465 TR4As produced (1965–1967)
Around 75% were IRS models
1966 was a peak production year, making the 1966 TR4A IRS one of the most common variants

The TR4A IRS has since become a sought-after classic, valued for its blend of 1960s British style, Michelotti’s timeless design, and improved drivability due to the independent rear suspension.