MGB Gearbox Conversion Kit 5 Speed Mazda - 5 Bearing Engine


Prices are exclusive of VAT

Available - Despatched 1-2 business days after order receipt


Vitesse Gearbox Conversion Kit using the proven Mazda MX-5 Mk3 5 Speed Transmission. 

SuitableMGB Gearbox replacment for all 1962-80 MGBs. 

Our MGB gearbox now comes with a period correct black gear knob to complement your vehicle's existing interior.

Also included in your MGB gearbox kit is a speedometer cable angle drive to provide a protected, smooth sweep of the cable exiting the gearbox.






Our kit includes the following:

  • NEW Mazda MX-5 5 Speed Transmission:
    • Vitesse Gearbox Case
    • Vitesse Bellhousing
    • Vitesse Machined Billet Front Plate
    • Modified rear case with Mazda mechanical Speedo Drive Assembly
  • Mazda MX-5 OE Clutch Friction Plate
  • Bespoke Shift Lever and Shift Knob kept in original position
  • Concentric Slave Cylinder Assembly
  • Braided Clutch Pipe and remote Bleed Pipe for easy bleeding
  • Prop Shaft
  • Spigot Bush with Mazda OE needle roller bearing assembly
  • Speedo Drive Cable and Angle Drive
  • Gearbox Rear Mount Bracket Assembly and Isolator
  • Complete Geomet coated UNF fixings kit
  • Clutch Alignment Tool


The gearbox comes fully assembled including the clutch slave cylinder assembly so the fitting is only as complicated as replacing an original gearbox. We even include a Mazda clutch alignment tool to assist with assembly!

We use all OE Mazda components where possible, ensuring parts quality and also serviceability.

All brackets are electrocoated ensuring maximum resistance to corrosion.


Smiths electronic speedometer option for MGA and MGB

A mechanical speedometer drive is included in all Vitesse Mazda 5-speed replacement gearbox kits, with a speedo cable to connect to the original instrument fitted to the car.

We can now offer a Smiths electronic speedometer for MGA’s and MGB’s as an option to the mechanical arrangement.

The kit includes:-

  • Mazda electronic sender unit fitted to the gearbox in lieu of the mechanical one
  • Wire harness with dedicated connectors at either end to connect to the sender and instrument
  • 4” (100mm) instrument for MGA and all chrome bumpered MGB’s. Note: Only available in negative earth form and cannot be switched
  • 3” (80mm) instrument for MGB GT V8’s and rubber bumpered MGB’s

The benefits:-

  • Easy to install
  • Easy calibration, saving on both cost and time of sending original mechanical speedo away to be re-calibrated
  • No problems with bouncy needle



The all-alloy case means significant weight savings can be achieved with this kit, up to 13.5kg! 


Gear Ratios: 

Gear Ratio - Mazda Transmission 
1 3.136
2 1.888
3 1.330
4 1.000
5 0.814


The standard MGB differential has a ratio of 3.909:1, is identical to the MX-5 differential, so the gear ratios work perfectly in the MG. Furthermore, the standard gear ratios of the Mazda gearbox are similar to the Ford Type 9 close ratio gear set, which attracts a significant premium over the standard Ford Type 9 gearbox!


12 months manufacturing defect warranty offered on all parts.

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