Landcruiser Gears

Scoop

Most vehicles don't give better fuel consumption figures with higher speed gearing.
The 5th is already an overdrive of around 0.87 :1 and increasing this to, for example 0.79 :1 may just cause you to be opening the throttle more to deliver more energy to overcome the taller gearing. So fuel consumption may actually rise.

Same may also occur if you change the diff ratios to a lower number ratio. ie 4.11 to 3.92.

The best thing to do is to find a friend who will lend you rims with bigger wheels of a known percentage increase and test run your originals, then run the bigger ones over a set distance and same loading/driving pattern to gauge results.

Your vehicle may be able to tolerate upping the gearing to some degree but until you evaluate it first the expensive tyre change 4 or 5 and or two diff gear sets + cost of the mechanical service to change them may not be cost effective.

The cost of bigger tyres or diffs may not give any great improvement and the cost of these for little gain may easily pay for the extra fuel you already use.

Is your vehicle in a top state of tune and injectors, valve clearances and timing adjusted properly?
Is your air cleaner clean and does your exhaust allow for free flow exit of gasses to maximize volumetric efficiency within the cylinder.

A $1000 of mod buys a lot of fuel if the intended advantages of the mod hardly do anything. Tread carefully, the theory is good, it just doesn't always work out well.

Ross M

With the V8 Troopy 4 years ago - In the middle of the NT.
I did two 300 k test runs towing a 3 tonne caravan.
One in 4th and one in 5th at about 90Ks/hr – there was no measurable difference in fuel consumption.
5th gear towing with a Troopy causes wear problems - there are no benefits, only disadvantages.

Would fitting a 3 inch exhaust system improve the economy on the v8 cruiser