tall ratios

[micksta323]

i have the standard ( i think ) 4.7:1 diff ratios in my series 3. are taller ratios available, and if so what ratios are there and where are these available/price etc? i have to drive to perth from cairns in 2 months and i'd like to go a wee bit quicker than 80 all the way! i also have a series 3 ex army 6 cyl ffr i want to git rid of before i go. any help is appreciated. cheers.

mick.

[JDNSW]

Standard is 4.7 as you have. 3.54 is fitted to Rangerover, Disco and 90/110 as well as Stage 1. Rangerover, disco, 110 front and 90 front and rear will fit the Series 3 except for the Salisbury diff fitted at the rear of the lwb. If you have a lwb, the Salisbury diff is not simple to change, but it can be done, and 3.54 gear sets are readily available. The Rover diffs especially from RRs are plentiful and cheap.

There are other ratios available, but they are rare and relatively expensive.

Other alternatives include -

1. High ratio transfer case gears - this has the advantage of only affecting high range.

2. Overdrive. In many ways the most satisfactory (you have the choice of gears), but against this is fact that the most common overdrive, Fairey, is not the strongest bit of gear out, and new or good ones are pretty expensive, as are parts. The Toro overdrive is better, but very rare.

3. Depending on what tyres you have at the moment, you may be able to fit larger diameter tyres to achieve a sufficient effective increase in ratio.

Depending on what engine you have, you may not find that a higher ratio is all that much advantage, and all the Rover engines are quite happy at the speed limit with standard gearing - although they may be pretty noisy (but most of the noise is not engine noise!). Rather than change the ratio, a campaign to quieten things may be something you could consider - replace body seals, fit insulation and sound deadening, possibly an electric fan, things such as that.

Hope this helps,

John

[LandyAndy]

Perhaps buy a 3.54 sailsbury diff complete for the rear only for the trip.Use only in 2WD.
If you are happy with the 3.54 after the trip its easy to get a 3.54 front rover diff to match.
If it struggles to perform as you like it you can then revert to a standard 4.7.1 as a swap with cash your direction.
Andrew