Gearing Option 1
MPH/1000RPM
Gear High Low High+O/D Low+U/D
1st 3.692 1st 5.1 2.2 6.5
2nd 2.132 2nd 8.9 3.8 11.3
3rd 1.397 3rd 13.5 5.7 17.3
4th 1 4th 18.9 8.0 24.2
5th 0.77 5th 24.5 10.4 31.4
Rev 3.429 Rev 5.5 2.3 7.0
High 1.41 Speed in high range at 1000RPM intervals
Low 3.32 Gear 1000 2000 3000 4000
Diff 3.54 1st 5.1 10.2 15.4 20.5
Tyre 31.7 2nd 8.9 17.7 26.6 35.4
O/D 0.782 3rd 13.5 27.0 40.6 54.1
U/D 4th 18.9 37.8 56.7 75.6
RPM 4000 5th 24.5 49.1 73.6 98.2
Rev 5.5 11.0 16.5 22.0
Gearing Option 2
MPH/1000RPM
Gear High Low High+O/D Low+U/D
1st 2.48 1st 8.8 3.2 1.2
2nd 1.48 2nd 14.7 5.4 2.0
3rd 1 3rd 21.8 8.0 3.0
4th 0.728 4th 29.9 11.0 4.1
5th 5th
Rev 2.086 Rev 10.5 3.8 1.4
High 1.222 Speed in high range at 1000RPM intervals
Low 3.32 Gear 1000 2000 3000 4000
Diff 3.54 1st 8.8 17.6 26.4 35.2
Tyre 31.7 2nd 14.7 29.5 44.2 58.9
O/D 3rd 21.8 43.6 65.4 87.2
U/D 2.69 4th 29.9 59.9 89.8 119.8
RPM 5500 5th
Rev 10.5 20.9 31.4 41.8
Gear Ratio Calculator version 1.1
Speed at listed RPM
High Low High+O/D Low+U/D
20.5 8.7 26.2
35.4 15.1 45.3
54.1 23.0 69.2
75.6 32.1 96.6
98.2 41.7 125.5
22.0 9.4 28.2
Speed in high range at 1000RPM intervals
5000 6000 7000 8000
25.6 30.7 35.8 40.9
44.3 53.2 62.0 70.9
67.6 81.1 94.7 108.2
94.5 113.4 132.3 151.2
122.7 147.2 171.8 196.3
27.6 33.1 38.6 44.1
Gear Ratio Calculator version 1.1
Speed at listed RPM
High Low High+O/D Low+U/D
48.3 17.8 6.6
81.0 29.8 11.1
119.9 44.1 16.4
164.7 60.6 22.5
57.5 21.2 7.9
Speed in high range at 1000RPM intervals
5000 6000 7000 8000
44.0 52.7 61.5 70.3
73.7 88.4 103.1 117.8
109.0 130.8 152.6 174.4
149.7 179.7 209.6 239.6
52.3 62.7 73.2 83.6
Inches in a mile63360
Pi 3.141593
Some notes to help find your way around this gearing calculator
1st to 5th - ratio of each forward gear in main gearbox
Rev - ratio of reverse gear in main gearbox
If a gear does not exist (ie 3 or 4 speed gearbox ) then leave value blank
High - ratio of high range gearing in transfer box, if no transfer box (ie direct drive from main gearbox) then set value to 1
Low - ratio of low range gearing in transfer box, if no low ratio then leave value blank
Diff - ratio of axle differential
Tyres - this is the rolling diameter of the tyre in inches
O/D - this is the ratio of an overdrive if one is fitted, if not leave value blank
U/D - this is the ratio of an underdrive if one is fitted, if not leave value blank
RPM - allows you to put in a rpm of your choice (eg max rpm) to see the speeds in all gears at this selected rpm
Note if you want to see the gearing for High+U/D and Low+O/D simply put the U/D ratio in the O/D box or vice-versa
Disclaimer
Use of this application is entirely at your own risk. I can not be held responsible for any errors, omissions or you injuring your
Life is dangerous and it ain't my fault.
Feedback
Any comments or queries can be directed to me at:
defender@blueyonder.co.uk
Gear Ratio Calculator version 1.1
from main gearbox) then set value to 1
n all gears at this selected rpm
D ratio in the O/D box or vice-versa
r any errors, omissions or you injuring yourself in any way.
Sample Data for Land Rovers
Some of the sample data has been reproduced with kind permission from John Barge's website:
http://members.shaw.ca/jbarge/
John's comprehensive gearbox data can be found here:
http://members.shaw.ca/red90/gears.html
Main Gearbox Ratios
1st 2nd 3rd 4th 5th Rev
LT77 early 90/110 3.585 2.3008 1.5074 1 0.8314 3.7007
LT77 V8 Disco/90/110 3.321 2.132 1.397 1 0.77 3.429
LT77 200TDI Disco/90/110 3.692 2.132 1.397 1 0.77 3.429
R380 V8 3.321 2.132 1.397 1 0.732 3.429
R380 300TDI/TD5 3.692 2.132 1.397 1 0.77 3.429
LT85 90/110 3.6497 2.1804 1.4362 1 0.7951 3.8242
LT95 RRC/101/110 4.0691 2.448 1.5049 1 3.6643
ZF4HP22 Auto 2.48 1.48 1 0.728 2.086
TorqueFlight TF727 Auto 2.45 1.45 1 2.2
Series II 3 2.043 1.38 1 3.02
Series IIA 3 2.22 1.5 1 3.02
Series III 3.68 2.22 1.5 1 4.01
Transfer Box Ratios
High Low
Series I, II, IIA 1.148 2.89
Series III 1.148 2.35
Series IIA 109, 6 cylinder 1.53 2.35
Series 1 Ton 1.53 3.27
Series 109 FC 1.53 2.92
LT95 RRC 1.113 3.3206
LT95 101 1.174 3.3206
LT95 110 1.3362 3.3206
LT230 Discovery/RRC 1.222 3.32
LT230 V8 90 LT85 1.192 3.32
LT230 90/110 1.41 3.32
LT230 110 1.667 3.32
LT230 TF727 1.003 3.32
Ashcrofts Low Ratio LT230 1.222 5.95
Maxi-Drive Low Ratio Gear Set 4.340
Axle Differential Ratios
Series LR 4.71
90/110/RR/Discovery 3.54
Other common ratios 3.8
4.11
4.75
Over and Under Drive Ratios
Ashcrofts Underdrive 2.69
Fairy Series Overdrive 0.782
Tyre Sizes
Nominal Diameter (inches)
205R16 28.9
235/70R16 29.0
225/75R16 29.3 This useful link will allow you to calculate the diameter for othe
7.50x16 31.0 http://www.tyresave.co.uk/tyresize.html
265/75R16 31.6
235/85R16 31.7
285/75R16 32.8
255/85R16 33.1
9.00x16 34.0
35x10.5x16 35.0
nk will allow you to calculate the diameter for other tyre sizes:
yresave.co.uk/tyresize.html