Aston Martin DB2 4-Speed Gearbox

Aston Martin DB2 (1950–1953) was a landmark vehicle that cemented David Brown’s legacy, featuring a gearbox that was actually manufactured by his own company, David Brown & Sons.

Listing Details

• Aston Martin 4-Speed Manual Gearbox
• Aluminum Case
• Removable Cover
• Output Flange
• Bell Housing

1. Technical Specifications

The DB2 utilizes a David Brown 4-speed manual gearbox, which was built as a unit construction with the engine.

• Manufacturer: David Brown & Sons.

• Casing: Light alloy.

• Synchromesh: Featured on 2nd, 3rd, and Top gears (1st gear is unsynchronized).

• Gear Ratios (Standard):

  • 1st: 2.92:1 (also listed as 11:1 with final drive)

  • 2nd: 1.98:1

  • 3rd: 1.33:1

  • 4th (Top): 1.00:1 (Direct drive)

  • Reverse: 2.92:1

• Final Drive: 3.77:1 (Standard), though 3.5:1 and 4.1:1 ratios were later options.

• Clutch: Large single-plate dry friction design (9-inch Borg & Beck).

2. Common Variations

• Close Ratio Gearbox: An optional “Racing Type” close-ratio gearbox was available for competition use, featuring tighter spacing between 2nd, 3rd, and 4th gears.

• Shifter Placement: The car could be ordered with either a central floor-mounted lever or a steering column change, depending on the client’s preference.

3. Maintenance & Fluids

• Oil Capacity: Approximately 1.3 liters (2.3 pints).

• Oil Type: Traditionally used a straight SAE 90 mineral gear oil or Vintage Gear 90. Modern equivalents often suggest a high-quality GL-4 rated 80W-90 (ensure it is yellow-metal safe for the synchros).

• Service Interval: Specialists recommend checking levels every 3,000 miles (4,000 km) and a full change every 10,000–15,000 miles.

4. Modern Upgrades & Parts

Because the original David Brown 4-speed lacks synchromesh on 1st gear and can feel “agricultural” by modern standards, many owners opt for conversions:

• 5-Speed Conversions: Kits using ZF or Tremec gearboxes are popular. These provide a synchronized 1st gear and an “overdrive” 5th gear for much more relaxed highway cruising.

• Sourcing Parts: Original internal components (gears, shafts, and synchro rings) are primarily sourced through specialists like Aston Service Dorset or Hutson Engineering.