http://www.landyzone.co.uk/lz/f16/transfer-box-offer-94762.html
get him to give it a clean so you know what ratio it is, the closer you can get to 1:1 the better, i am not suggesting that such a box exists just the closer you can get the better
Not strictly True! Sorry Bevhelee, tis the other way around:
Ok available ratios are for LT230 transfer boxes,
1:1.00,
1:1.22,
1:1.4,
1:1.66
Ok its actually reversed as in what ever transfer box it it into 1
so 4th gear 1500 RPM, output at Transfer box
1.00:1 output of transfer box, - 1500RPM - 423 RPM at wheel,
1.22:1 output of transfer box, - 1230 RPM - 347 RPM at wheel,
1.4:1 output of transfer box, - 1071 RPM - 302 RPM at wheel,
1.66:1 output of transfer box, - 903 RPM - 255 RPM at wheel,
Ok now what size are your tyres not what is on the tyre sidewall or whatever. You need to measure the height from bottom of the tyre while the vehicle is on the ground to the top of the tyre then take off approx 10mm. that is your diameter.
205R16 28 inches, * 2.54 to get centimeters so 71.cm.
to get a circumference of a circle you need to calculate:
3.1415 x d So:
3.1415 x 0.71 meters = 2.230 Meters, So one full revoloution of a 205R16 tyre equals 2.230 Meters.
Then we need to get it into meters per second to then equate it into a meaningful Miles per hour.
so 1 Meter a second equals 2.23693629 Miles per hour.
423 x 2.230 = 943 RPM = 15.72M/s = 35.16 Miles per hour
347 x 2.230 = 774RPM = 12.89M/s = 28.83 Miles Per hour
302 x 2.230 = 673RPM = 11.22M/s = 25.10 Miles per hour
255 x 2.230 = 569RPM = 9.47M/s = 21.18 miles per hour
So to sum up depending on what transferbox you have makes a huge difference to what you can expect to achieve. V8 had the 1:1 because they have enough power to pull that gear ratio for the given 205 size tyres. On the other hand 110, 130 4 cylinder diesels had 1.66:1 transfer boxes because they were fitted with 750R16 or 825R16 tyres and did not have all that power of a v8 to pull the ratios and vehicle.
I have spent many hours working the above out for all ratios and gears and indeed low range and with different ratio diffs.
I currently run a 90 with 37 inch tyres with a disco 200 tdi and discovery transfer box the gearing is silly high to the point that 5th gear is not all that usable. If i put on 205R16 tyres everything is good. My soloution is to change my diffs to 4.7 ratio diffs (lots of pros and cons) but the short of it is I want a lower low range and high range and this will be best for me. driving in low range such as comps my low range is horrible far too fast in first gear and for decending rocks way way too fast for my liking.
May I suggest you get a serial no and find out what you have got sounds like you have a disco transfer box or indeed a RR one if this is the case you can get another one more suited to your needs. but low range will stay the same all low range are the same ratios on all LT230 transfer boxes.
