Overdrive advantage for a diesel defender?

[Rob]

I have a 130 with the 2.5 diesel turbo and a 5 speed gear box. It cruises at 100kph alright on the flat (285/75R16s) but I am wondering if the addition of an overdrive (such as a roverdrive or similar unit) is of much benefit considering the ratios of the 5 speed gearbox. My thought is that the available horsepower and power band is probably maxed-out already so an overdrive won't be much accomplishing much at highway speed. I'm not looking at going faster just looking for a little less noise and a bit better fuel economy. Anyone have experiences with this sort of a diesel 5spd rig and an overdrive? I'd appreciate hearing your thoughts about your experiences.

Cheers, Rob

[rayhyland]

I have a Roverdrive on my 200tdi 110. I think it is very good.

Lowers the engine revs and the noise dramatically.

Ray

[HeadDamage]

What is the ratio of the Roverdrive when it is engaged? I've been trying to figure out if it would be useable as a gear spliter with my LT77G (military gearing) and 1.667 LT230. When my 200tdi is ready to go in I'm thinking of keeping the 1.667 so that I can better tow in high range but use a Roverdrive for when not towing, it would be nice to split gears with it as well if the ratio works out.

[rayhyland]

28% gear reduction.

It acts as a 6th gear

[red90]

The answer depends on what exact gearbox and transfer case you have. There are different ratios available. If you can provide the serial number, that would help.

[HeadDamage]

I know what ratios I have, what I haven't found anywhere is what ratio the Roverdrive is. 28% is not a ratio though it can help estimate what it might be.