Defender Upgrades: Gear Ratios - Should you change them?
If you drive a Land Rover Defender, you know that this rugged vehicle is as versatile as it is tough. One modification that’s frequently talked about is either changing the 5th gear ratio in the R380 gearbox or altering the LT230 transfer box ratio from 1.4 to 1.2. While both changes aim to enhance driving comfort and performance, they achieve these goals in different ways. Understanding the nuances of each option will help you decide which modification best suits your driving style and needs, if any of them
Gear Ratios 101: What’s the Difference?
R380 Gearbox 5th Gear Change: The standard 5th gear ratio for the R380 in a 300Tdi or Td5 is 0.77:1. By swapping to the V8’s 5th gear ratio of 0.732:1, you can increase the ratio of the 5th gear by 5%. The main outcome is to reduce the rpm of the engine when cruising at highway speeds, it can also lead to a slight improvement in fuel economy and a reduction in engine noise while cruising. However, it only impacts the RPM when you're in 5th gear.
LT230 Transfer Box Ratio Change: The LT230 transfer box has a standard ratio of 1.4:1. By changing this to a 1.2:1 ratio as used in the Discovery, you effectively "up-gear" the entire drivetrain when in high range by 15%. This means a more significant drop in RPM across all gears, enhancing comfort and efficiency. Importantly, this change does not affect the low range ratios, which remain the same for off-road capabilities.
The Impact on RPM
The difference in RPM reduction between these two modifications is quite significant.
R380 Gearbox 5th Gear:
Standard 5th Gear (0.77:1): At 60 mph (96 km/h), the engine typically runs around 2600 RPM.
V8 Gear (0.732:1): After the swap, that RPM drops to approximately 2450 RPM. While this reduction helps, it’s a modest change.
LT230 Transfer Box:
Standard Ratio (1.4:1): At the same speed of 60 mph, the engine runs at about 2600 RPM in 5th gear.
Modified Ratio (1.2:1): With the new transfer box ratio, RPM at 60 mph drops to around 2200 RPM. This reduction is much more substantial and impacts driving comfort significantly.
Driving Speed and Performance
The changes in RPM directly affect driving performance. With the R380 gear change, the benefit is primarily felt in 5th gear, which means that low-speed performance, particularly in urban environments or off-road, remains unchanged. You won’t notice much difference when accelerating from a stop or driving at lower speeds.
In contrast, changing the LT230 transfer box ratio improves performance across the board. The overall gearing becomes taller, allowing for a more relaxed driving experience at all speeds. However, remember that the low range gearing stays the same, preserving your off-road capabilities. If you often find yourself driving on highways or longer distances, the LT230 upgrade is likely to yield more noticeable benefits.
Conclusion
Choosing between changing the 5th gear ratio in the R380 gearbox or swapping the LT230 transfer box ratio ultimately depends on your driving habits and priorities. If you frequently cruise at medium to high speeds, changing the transfer box ratio to 1.2:1 offers substantial benefits. On a performance tuned 300Tdi or Td5, the additional power will make the higher gearing effortless. If you predominantly use your Defender around town, regularly have it fully loaded or tow behind it, and only occasionally see highway speeds, then the 5th gear ratio change might be more suitable.
Both modifications can improve your Defender’s driving experience, but the LT230 transfer box swap delivers more significant reductions in RPM and enhances comfort across all speeds. Whichever option you choose, understanding the differences between these two approaches will help you get the most out of your Land Rover Defender.