Diff Ratio

Land Rover Crown Wheel & Pinion Gear ratios


If you are increasing the payload of the vehicle or changing the tyre size then the gearing dynamics need to be changed.  With the ratios below, we can offer both speed reduction or speed increase to suit your application combined with considerable extra strength of the  gear tooth profile and design changes to maximize the crown wheel thickness.

After 19 year for production for not just Land Rover gears but 50 + top end motor sport application up to 600 BHP we understand the requirements and the reasons for failure for this particular application.  Tooth failure is very rare with our increased tooth size we have also balanced an increased in the crown wheel thinness to stop flexing of the crown wheel and carrier. Please see the section on diff pegging as this is the next recommendation for high performance vehicles.

3,54 is the standard ratio from Land Rover. With KAM ratios fitted you can see from the table the changes that are possible.The torque increases are calculated by using the standard gears as a datum.  Input torque is produced by the engine power put into the differential and output torque is produced by the feedback into the differential from traction obtained.


Land Rover
3.8 ratio up to +70% in engine motor torque
3.8 ratio up to +50% in tractive effort at road

Fitting Pinion Shimming / Height setting
All KAM gear sets are ground to within 2 thou of the original OEM.  The intolerance is not in the gear but in the diff casing.  If you use the original shims from under the pinion head bearing then 95% of the time the KAM replacement ratios will not require re-shiming.  Effectively we have done the hard work and this gives the customer an easier job on setting up.

Pinion Height Setting Block
A height setting block can be purchased from KAM or Land Rover £95.00 each if you have lost the original shims and would like to check using a service tool.
Height Block 39.50 Inpiricel   38.20 Metric.  30.93 Salisbury


This height is measured from the top of the pinion head to the bottom of the carrier bearings. Full fitting instructions are available on the KAM web site with 26 line drawings of how to rebuild the complete Land Rover diff.


Height Block                          Tooth connections         Full instructions on building your diff

Images used with kind permission of Land Rover Publications Ltd


KAM gears are designed to fit straight in to Land Rover 3.54 ratio diff carrier units. The design of KAM’s crown wheels has been changed to increase strength and reduce the problem of crown wheel ‘flex’. This change means that our crown wheels are 13mm thicker than standard, in turn this means that in some differential housings it may be necessary to grind some material away to allow room for the much larger KAM crown wheel and pinion gear set, a small price to pay we feel for the peace of mind a KAM gear set brings you!
All KAM gears will fit original Land Rover carriers and ARB, Detroit, Quaife or Tru -Trac units.


We offer a range of alternative ratios that have been specifically designed for competition, commercial and military Land Rover applications.  We offer a choice of ratios to suit the varying engines and tyre sizes used around the world.


Chemical Blacking
We do not undertake this process on our Land Rover gear sets.  It is not a requirement of our OEM production and just adds to the cost of the gears.   For corrosion resistance we adhere to the Land Rover specification requested which is grease dipped and wrapped in corrosion proof paper.  Why add a process and cost to a gear that sits in oil all of its life. 

KAM Crown wheel bolts
Crown wheel bolts are always recommended to be changed as they suffer fatigue.
There are also 2 different types of bolt size.
Course     3/8 20h UNF 1948> to <1986,     237339       Old 4.7 ratio
Fine          3/8 24h UNF 1986 >                    FTC 3586   3.54 ratio and all KAM ratios.
KAM produces their own 3/8 24h UNF 12/9 strengthened bolts fine type which are also 4mm longer to compensate for the thicker crown wheel.

These new bolts are each 2 tons stronger than the original Land Rover ones,  which give a increase of 20 tons of shear strength from normal.  They also have a longer plain portion under the head to give better support on the crown wheel body to the carrier.

Free advice of fitting

Just call us and we are happy to run over any problems you have or if it the first time you have built a diff unit we are here to help.  Call +44 01483 419779
Or we charge just £90 for fitting any ratio plus any parts required.
Carrier change only £40,00 plus any parts required.

Please ask for price for the below applications

Frazer Nash                   Hewland                            MGB V8


Land Rover                 Sierra 7” &7 .5”           Atlas


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