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MG TB/TC 5 Speed Gearbox Conversion Kit

The MG TB/TC 5 speed gearbox conversion kit has been developed as a further successor to the popular TD/TF, MGA, MGB and Magnette 5 speed conversion kits designed and developed by Hi - Gear Engineering Ltd.

The Kit is aimed at TB/TC owners who really want to use their cars on modern roads including motorways and who do not want to be confined to secondary roads.

MG TB/TC 5 Speed Gearbox Conversion Kit

With normal gearbox on modern roads keeping up with traffic, the engine revolutions become altogether too high for economy, comfort and engine life.

The conversion adapts a Ford Sierra type 9 gearbox (5 speed 1.6 L & 1.8L 1982 - 1991, and 2L. 1982 - 1987) to the XPAG engine.

The 5 speed kit has all the parts necessary for the competent owner to fit the type 9 gearbox to the car with all fasteners and comprehensive fitting instructions.

The Ford type 9 gearbox is not part of the kit but is either supplied by the owner or Hi - Gear Engineering Ltd.

The vehicle speedometer will need recalibrating. Several companies are able to do this. Instructions on how to measure the vehicle speedometer characteristics for recalibrating are included together with the details of a suitable company to do the work.

The Kit Comprises TB/TC

  1. Cast aluminium bell housing
  2. Gasket, bell housing to gearbox
  3. Spigot bush
  4. Clutch plate (driven)
  5. Special design gearbox mountings (2)
  6. Gearbox mounting support plates (2)
  7. Gear lever assembly (guickshift precision type)
  8. New prop shaft assembly
  9. Gearbox cover packing pieces (2)
  10. Speedo cable
  11. Gearbox cover to propshaft tunnel filler piece
  12. Propshaft safety guard
  13. Propshaft tunnel stiffening angles (2)
  14. Loctite
  15. Detailed fitting instructions
  16. Roll pin for clutch shaft (replaces taper pin)
Gear Ratios TB/TC Standard Ford Modified Ford Closer Ratio
First 3.38 3.65 2.98 3.36
Second 1.95 1.97 1.97 1.81
Third 1.35 1.37 1.37 1.26
Fourth 1.00 1.0 1.0 1.0
Fifth - 0.82 0.82 0.825

The bell housing is cast in high strength LM25 heat-treated alloy and is robustly constructed. The standard MG 71/4'' clutch cover is reused. The standard clutch release bearing and cross shaft system are retained.

MG TB/TC 5 Speed Gearbox Conversion Kit

We can also supply the correct bell housing / clutch plate if the TB / TC has been fitted with an 8'' clutch system.

The gear lever sits exactly in the original position, consequently the conversion is not easily detectable.

The engine stays in its normal position and there is no cutting or drilling of chassis. The gearbox cover is re-used.

The front end of the propshaft tunnel (under the gearbox cover) must be modified to accommodate the longer gearbox.

The conversion transforms the car into a usable cruiser. Other benefits include improved fuel consumption, less driver and passenger fatigue, less vibration, longer engine life and fewer broken crankshafts.

TB / TC Axle Ratio 5.125/1

Standard wheels and Tyres
4th gear 16.25 MPH / 1000 RPM
5th gear 19.8 MPH / 1000 RPM
70 MPH (4307 RPM) - 3535 RPM (5th gear)

The propeller shaft provided in the: kit is to the original manufacturer's specification:

Torque: 570 Nm, 422 1bf.ft. (short duration) MAXIMUM.
Speed: 7000 RPM MAXIMUM.

This corresponds to 5740 engine RPM in fifth gear (ratio: 0.82:1) and 7000 engine RPM in fourth gear (ratio 1:1). For any higher values of torque or speed, Hi - Gear Engineering Ltd can refer the customer to the Manufacturer.

Price £1160.00 Plus delivery, packing and VAT @ 20%

For more information on our gearbox conversions for classic MG cars
Call Hi-Gear Engineering Ltd on Tel: 01332 514 503

Suppliers of Five Speed Conversion Kits to:


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