Fitting a 5-speed gearbox on a 1962 blue Series 1 E-Type

Back in May, we welcomed a stunning blue 1962 Series 1 Jaguar E-Type to our workshops. This major project focused on the conversion from the original gearbox to a modern 5-speed transmission. This extensive mechanical work involved removing and recommissioning the engine and drivetrain. This project required much more than simply replacing the gearbox; it required modifications to the transmission tunnel, clutch system, exhaust, interior and controls, all whilst retaining the character and appearance of the original E-Type whilst improving usability and drivability. This article will cover in detail the process of installing the 5-speed gearbox into one of Jaguar’s most iconic models.

To begin the restoration process, we removed the bonnet to gain access to the engine bay, then we removed the engine, gearbox, clutch, radiator and header tank from the E-Type. Once the engine and parts were removed from the E-Type, our attention turned to the fuel system. The fuel tank and pump were stripped and thoroughly cleaned, then any existing fuel leaks were identified and fixed. Additionally, the carburettors were fully stripped and cleaned, new spark plugs were fitted, and the engine was brought back to running condition.

With the engine removed, the work provided an opportunity to service a number of its associated components. The inlet manifold was removed, and its old gasket material scraped away from the mating face, preparing the surface for a clean seal. The water pump, crankshaft damper and header tank were also serviced. New engine mounts were installed, while the engine brackets were refitted to prepare for the eventual installation back into the Jaguar. In addition, the sump was drained of oil and removed for a thorough clean before being reinstalled with fresh oil.

Once the work was complete in the engine bay, we began working on the five-speed gearbox mechanical conversion. The move to a five-speed gearbox required careful preparation of the drivetrain. The original flywheel and spigot bush were removed, making way for the components supplied as part of the conversion kit. A new spigot bush adapter was installed, while three custom clutch dowels were fabricated and pressed into the new flywheel. These bespoke components allowed the flywheel and clutch assembly to be prepared for the new transmission arrangement. The original bellhousing was removed and thoroughly cleaned before being mated to the new five-speed gearbox. Then this combined assembly was fitted back onto the engine. Additionally, the clutch system needed to be adapted. A clutch slave cylinder was fitted, and a bolt was custom-turned to create a functional clutch pushrod. The pushrod was adjusted until the clutch operated correctly, followed by final operational checks.

Moving to a five-speed gearbox offers several benefits for the classic Jaguar and our client, including more relaxed cruising, reduced engine revs at higher speeds and a more comfortable driving experience on longer journeys. The additional gear provides greater flexibility across different road conditions, while the modern transmission can make the car more practical for everyday and touring use.

In order to fit the new, larger 5-speed gearbox, we needed to make some fabrication and structural modifications, which involved adapting the original transmission tunnel. The original tunnel crossmember was cut out to create the necessary clearance. New steel reinforcement plates were then fabricated, cut and ground to shape before being welded into position. A custom gearbox mounting plate was fabricated, along with top spacers and new body mounting points, providing the mounting arrangement needed to secure the new transmission. The work continued underneath the E-type, where former mounting points were tidied up. The centre exhaust heat shield was cut down to clear the new transmission bracket, and the exhaust system was refitted and adjusted around the modified installation.

With the transmission tunnel modified to accommodate the larger five-speed gearbox, a new cover was required to enclose the installation. The existing metalwork was cleaned up before creating a tape mould and laying up a bespoke fibreglass cover. This was then sanded, smoothed, painted and bolted into place, providing a neat finish ready for the interior trim and centre console. To adapt the interior to fit the new gearbox, the gear stick was shortened to suit the new arrangement, while a new reverse light switch was fitted. The handbrake assembly was altered to work correctly with the revised interior set-up. The switch/trigger spring was adjusted until the handbrake operated correctly and the dashboard warning light functioned as intended.

Furthermore, another area of the Jaguar that needed updating was the speedometer. This involved addressing and rearranging the cable routing and length to accommodate the new gearbox. We trial-fitted an angle drive as a potential solution and removed the speedometer unit for custom calibration. Once calibration was complete, the unit was refitted. The speedometer reading was then checked during subsequent road testing, allowing any further adjustments to be made.

Alongside the drivetrain conversion, further work was carried out on the E-Type's front suspension. Dust gaiters on both the upper and lower ball joints were replaced, while the reaction plate was reinstalled and the front suspension assembly reconnected. The vacuum bellows were also refitted, followed by testing and adjustment of the vacuum levels to ensure the system operated correctly.

With the engine and gearbox prepared, the complete assembly was repeatedly test-fitted into the engine bay. This allowed clearances around the engine, transmission and surrounding components to be checked before final positioning. Adjustments were made during the process until the engine and gearbox package settled into its intended position. Once the five-speed gearbox was installed, initial test drives were carried out to assess its operation and the general performance of the new drivetrain. This allowed the team to fine-tune the engine. This was an important step in the installation process because, in this case, it revealed that the clutch, handbrake and speedometer needed to be refined during the shakedown process.

The Series 1 Jaguar E-Type's five-speed gearbox conversion required a combination of mechanical expertise, fabrication and careful interior adaptation. From recommissioning the original engine and preparing the drivetrain, through to modifying the transmission tunnel and fabricating bespoke components, the work demonstrates the detailed engineering involved in integrating a modern transmission into a classic Jaguar. If you are looking to upgrade or restore your classic Jaguar, please contact us with confidence. Call us on 0115 926 2266 or email us at info@thorntonrestorations.com.