Jaguar XKE Series I 4-Speed Gearbox

4-speed manual gearbox in the Jaguar E-Type (XKE) Series I is a tale of two very different transmissions. Depending on whether you have a 3.8L or a 4.2L car, the driving experience and mechanical internals change completely.

Listing Details

Four-Speed Manual Gearbox
Produced for 1961–1967 Jaguar XKE Series I Models
Designed by Moss
Gearbox Stamping: EB 13333 JS

1. The “Moss Box” (1961–1964)

Used in all 3.8-liter E-Types, this gearbox was designed by the Moss Gear Company. It is legendary for its durability but notorious for its “agricultural” feel.

Non-Synchromesh First Gear: You cannot shift into 1st gear while the car is moving without a perfect “double-clutch” and rev-match, or you will hear a loud metal crunch.
Identification: Serial numbers usually start with the prefix EB (e.g., EB 1234 JS).
The “Whine”: Features straight-cut 1st gears, which produce a distinct, loud mechanical whine that is perfectly normal for this unit.
Common Issue: A “stuck in first” syndrome often caused by wear in the interlock mechanism or the selector rods.

2. The Jaguar All-Synchro Box (1965–1967)

When Jaguar upgraded the E-Type to the 4.2-liter engine, they replaced the Moss box with a new, in-house designed fully synchronized 4-speed unit.

Full Synchromesh: Allows for smooth downshifts into 1st gear while rolling, making it significantly more user-friendly in modern traffic.
Identification: Serial numbers typically start with the prefix EJ (e.g., EJ 8577).
Reverse Location: On the Moss box, Reverse is typically “left and up”; on the Jaguar all-synchro box, it moved to a different position (often “left and down” or protected by a lockout).

Comparison at a Glance

Feature	Moss Box (3.8L)	Jaguar Box (4.2L)
Synchro on 1st?	No	Yes
Shift Speed	Slow / Deliberate	Moderate / Modern
Gear Cut	Straight-cut (1st/Rev)	Helical (Quieter)
Typical Value	$800 – $1,500 (Used)	$2,000 – $3,500 (Used)
Maintenance	Requires heavy SAE 90 oil	Uses lighter gear oils (e.g., Castrol)

3. The Modern Alternative: 5-Speed Conversions

Many Series I owners remove these original 4-speed units to install a Tremec-based 5-speed (like the JT5 or kits from The Driven Man).

Why? The 5th gear acts as an overdrive, dropping highway RPMs from ~3,500 down to ~2,200, which saves the engine and makes long trips much quieter.
Value Tip: If you buy a car with a 5-speed already installed, always ask for the original 4-speed box. To a collector, a “matching numbers” car must have its original gearbox to command top-tier pricing.