patrol diff ratios

G'day Mick'n'Jen
If you want to gear it to be 2000rpm, it is a factor or about 8% at 100kmh.
This can be done two ways, by either altering the diff ratios of both diffs and is quite expensive unless you know where to get some replacement lower ratio/higher output speed diffs or gear sets.

The other way is to fit larger tyres. Many people do this and depending on what size tyres you already have some increase "may" be beneficial.
After you pass the torque versus load aspect of the vehicles ability you will experience increased fuel consumption as the engine is now trying to drive the same load but with a overall engine to road ratio equivalent to 6th or 7th gear, again depending on the initial and final tyre sizes.

Best to test the tyre option by borrowing a friends bigger wheels to find if it is suitable for your needs.

Seeing you want to up the speed and also reduce the revs a significant amount I would think it won't be economical to go past the halfway mark of your expectations. Possibly around 2100 at 100kph before you start to go out of whack with the load/speed.

Ross M

Mick! Have a look on the Patrol 4x4 forum, there is a lot of info on this. I think the ute has a bigger, heavy duty diff carrier and housing so the ratios may be limited due to this. There are many guys on patrol forum that would swap carrier and or housings so they can use there vehicles for chewing through the scrub or whatever they do.Check the forum, they know more than me about this!!! Michael

Why do you want to get the revs down? As has been said, the easiest way is through minor tyre size change (with a speedo re-cal). But you will use more fuel and really blunt performance, especially when loaded, with 'step-off' around town and with off-road

IMO, the most effective way to do this would be to simply change the 5th gear ratio..

Gearmaster Nissan Overdrive Gears from Marks Adaptors


:)

bear in mind that the engine produces optimum torque at around 2500, so you probably do not want to drift too far away. That said i run 33s on a GQ ute and sit around 2150 at 100. The additional tyre size/weight is noticeable and will add about 10% to your fuel economy (to your detriment).

I've seen a few people talking about changing the highway revs on big 4wds of late.

It seem to me thay don't get it.

This is not a light pasenger car that has plenty of surplus power and is light incomparison to the engine capacity and at 100KPH is traveling at well below (like 1/2 or 2/3) its capable road speed.

Ya patroll is over 2 tonnes unloaded, proabably over 3 tonnes fully loaded, its a big lump of a thing and is pushing a lot of air in front of it.

The engine and gearing will be designed to keep the engine on the peak of its torque curve, at highway speeds, this is where it produce the best highway fuel economy.

This is particularly so of diesel engines.

There is no way arround the fact that the big nissan chews the juce, if ya try and drive it like a pasenger car on the highway it will get expensive.

Get used traveling a bit slower and not being the fastest thing on the road.

cheers

Hi Mick'n'Jen,

Please just have a thing about this. You are driving one of the best 4wd's made and that comes from a Tojo owner.

When Mister Nissan (JAPAN) made that vehicle they matched the engine to the best engine life and the best fuel economy. The old 94 engine was even better.

Here is an example. I run big tyres and the reason for this is 2 fold. I tow a lot and have to use 4th gear because my gearbox can't handle the load on 5th gear . This causes a problem with engine revs, so the big tyres. I can get away with this because the engine I have develops heaps of torque.

Now for the other reason. My engine develops max torque at around 1800 rpm, but my best fuel consumption is between 2200 and 2300 revs. With the bigger tyres I balance noise, fuel consumption and acceleration and I do get great fuel consumption out of the old clunker.

Hope this helps.