Terrafirma offers a range of alternative ratio crown wheel and pinion gear sets originally developed by renowned engineering company, KAM Differentials.
The optimum final drive ratio can be selected to accommodate increased tyre diameter, up rated engine performance and vehicle application. The increase in strength is measured by using the standard 3.54:1 ratio as a baseline, calculating input torque, produced by the engine power and output torque produced by the feedback into the differential from traction obtained.
Up to 25% gearing reduction coupled with up to 70% increase in strength is possible with Terrafirma lower ratio crown wheels and pinions.
3.54:1 is the standard ratio on all Defenders, Discoverys and Range Rover Classics. Lower ratios of 4.1:1 and 4.75:1 are available. The effect of these lower ratios can be seen in the chart.
For convenience the same ratio differential assembly was fitted to the front and rear axles. As a result, the front differential rotates in the opposite direction to the rear with the driving force being applied to the back of the gear teeth significantly weakening the meshing of the gear teeth. Terrafirma produce ring and pinion sets for the front differential assembly that are ?reverse cut? which ensure the force is applied to the stronger/correct side of the gear teeth.
- 4.1 & 4.75 available
- Reverse cut front option
- Up to 70% stronger
- 43% thicker crown wheel
- 40% larger tooth profile
