XK150 T5 - Other parts needed

Page list


These  parts are needed to complete the T5 conversion:

  • Prop shaft / tail shaft (if not in kit)

  • 2.3 litres of Dexron III oil

  • Optional: New spigot bearing (bronze or needle roller)

  • Ford-style speedo cable adapter and cable with 12mm speedo nut, 165cm long

  • Speedo driven gear - T5 Ford plastic
     - 4.09 rear axle: 18 teeth (yellow)
     - 3.54 rear axle: 16 teeth

  • Reverse gear switch connector

  • Two 1/4" UNF x 1/4" long grub screws

  • Two M8 nuts (gear lever adapter)

  • Optional: Small amount of steel or aluminium sheet for the steel transmission tunnel to be modified for the reverse gear switch connector

  • Possibly: 1/2" UNC x 1-1/2"
    setscrew(s) to bolt original bell housing to T5 adapter plate. 

And for the optional transmission tunnel modifications to allow the T5 to be removed without having to disturb the engine:

  • Aluminium or steel sheet

  • Four 1/4" UNC x 1" long caphead setscrews, spring washers and nuts

  • Ten 10g x 15mm round head self-tapping screws


My T5 kit had a custom-made sliding output flange to fit the standard XK Hardy-Spicer flange. The prop shaft supplied in the kit was of fixed length: 708mm (27-7/8") flange face to flange face. The new prop shaft was noticeably lighter than the standard XK prop shaft.

The output flange on the gearbox was bright steel, unpainted. A coat of black paint was applied to the non-contact surface before using it for the conversion.


Page list


Before starting the conversion, unless you are sure the existing spigot bearing is in good condition, suggest you have a replacement spigot bearing or needle roller bearing (1/2" ID x 3/4" OD x 3/4" long) on hand.


The speedo adapter supplied with the kit is shown. The driver wormgear on the gearbox output shaft has seven teeth. The adapter gear had 21 teeth. The standard XK150 speedo, and the speedo in my car, is 1200 turns per mile. The required driven gear the the correct odometer reading is 18 teeth on a car with the 4.09:1 rear axle (overdrive) ratio. It is not possible, maybe even impossible, to easily change the supplied adapter to accommodate an 18 tooth driven gear. In short, the supplied speedo drive adapter was useless.

For a non-overdrive XK150 with the 3.54:1 rear axle, the supplied driven gear would be 35% too many turns per mile!

Note: The USA standard for US car speedometers and speedo adapters is 1000 turns per mile. Even that fact does not explain why the adapter in the kit was so far out.

The solution for the gearing problem is to buy a 165 cm (65") speedo cable complete with the 12mm Smiths-compatible nut on the speedo end, and standard Ford adapter, which allows the user interchangeable plastic driven gears to be used. Unless the vehicle has a markedly different tyre diameter, then the yellow 18 tooth T5 driven gear is perfect for the 4.09 rear axle.

If you are fitting a T5 to a car with a 3.54 rear axle, then be aware that the T5 Ford plastic gear with the least teeth is 16. The theoretical tooth count required is 15.6. A 16 tooth gear will understate speed and distance by ~3%.



Page list


There is insufficient lateral space between the T5 gearbox reverse light switch and the transmission tunnel and left-side timber ply floor panel to fit a standard Ford reverse switch two-pin connector. Not only does the transmission tunnel have to be modified in a small way, but a special reverse switch connector has to be made.

Source a two standard 20 amp household electrical cable connectors, as shown. Remove the plastic moulding from each, and then solder a sheathed two-core cable to the brass connectors as shown. Then fit black heat-shrink cable, and trim the holes clear to finish the connector device.

After fitting to the T5, apply silicon sealant to and between the two connector parts to form a single connector unit.

reverse connector in place

Note the lugs removed from the gearbox case, and the cutout in the ply floorboard.

reverse switch connector

reverse cable connector

reverse cable insulated

Page list