Schuler - Ferguson Formula - Service and Maintenance Instructions

Range Rover Conversion 
Ferguson Formula   
All-Wheel-Control system

Driving - Service and Maintenance Instructions

SCHULER PRESSES LIMITED                                                                      February 1981
High Street                                                                                                     Vehicle no: 10.0163
Ascot, Berkshire


Your vehicle has been fitted with the universally acclaimed Schuler FF transmission.
The benefits you can now expect from having chosen the best in four wheel drive are listed below.

We would  like to wish you many miles of enjoyable motoring and assure you of our best attention at all times.


Higher Overall Gearing: - Less noise, less wear, less fuel wastage.

Economy: - 5% better with automatic. 15% better with manual, due to reduced power losses in 
transfer box, advantageous overall gearing and reduced weight.

Handling: - 37% front / 63% rear torque bias from special centre differential improves both 
response and stability to give an unrivalled level of safety and control.

Traction: - Automatic limited slip centre differential prevents wheelspin with viscous action to 
cushion shock loads and protect driveline from damage.

Reduced Noise: - Silent transmission and reduced engine revs drastically reduce interior noise 

Backlash: - Special Morse-Chain drive system is free from snatch due to tolerance build up.

Braking: - Viscous centre differential prevents instability due to uneven wheel lock up. Optional 
Anti Skid system gives freedom from control loss due to locked wheels. Optimum deceleration 
is available and the driver is free to steer the vehicle to safety.

Reliability: - From the outset, Schuler FF transmissions were stressed for engines of considerably 
more than 3.5 litres. Generous margins of safety are allied to the reliability reaped from our 4 year 
development programme to give a product that will many years of superior and uniquely enjoyable 
A 12 month unlimited mileage warranty is provided on all conversions.

                                                                                                                                                          Rare Schuler-Voith FF - Service and Maintenance Instructions



It should be emphasised that the ultimate limitation of car control is the grip between the tyres 
and the road surface.

The Ferguson system of All-Wheel-Control helps the driver to use the full potential grip to the 
best advantage in all conditions, but it cannot increase it; therefore, the car should always be 
driven with due regard to the prevailing conditions.

An FF vehicle handles in the normal manner, but with a greatly increased margin of safety 
when accelerating, braking, or cornering. The best characteristics of front and rear wheel drive 
are combined.


On vehicles fitted with anti-skid brakes the driver will feel a kick back through the brake pedal 
when the anti-skid system comes into operation. This is normal and is a warning that you could 
be driving too fast for the road surface conditions and your speed should be adjusted 

It must be stressed that the ultimate limitation on braking is the grip between the tyres and the 
road. Therefore great care should be taken on very slippery surfaces. The anti-skid system will 
enable the available grip to be used fully. But it cannot be expected to compensate for errors 
of judgement on the part of the driver.

                                                                                                                                                  Schuler FF advert - Automatic - Ferguson Formula - Anti-lock braking


                   NORMAL                                            SPORTS (SPECIAL ORDER ONLY)                    
Fig 1 (See text)                                                                                                                          The famous Schuler converted 'Automatic FF' - badge on many RRCs


Fig 2

                                                                                                                                                        The more rare manual 5 speed JRT Schuler FF conversion


GENERAL - The automatic gearbox has been specially developed to give the best in smooth 
and effortless driving. 
Special attention to shift points gives an impressive blend of performance with economy. 
fatigue due to stress is significantly reduced.

SELECTOR OPERATION - The centrally positioned selector lever allows free movement 
through those positions marked on Fig. 1 with arrows. All other movements require the button 
on the side of the T-bar selector to be depressed. Once the buttons is depressed, it is possible 
to engage any gear. It should not be depressed when the lever is being pushed forward and 
the car is in motion as this could involve the accidental selection of Reverse or Park.


P      The engine will only start with the lever in P or N.
        This is for reasons of safety. In the P position the gearbox output shaft is locked to provide 
        a back-up parking brake. It is not recommended that it be used for securing the vehicle on 
        slopes as it may prove difficult to disengage due to loadings on the locking mechanism. 
        On no account should P be selected with the vehicle in motion as transmission damage 
        will result.                                                                                                                         Converted Range Rover by Wood & Pickett with Schuler FF automatic

R      Reverse. Never engage this position when the vehicle is moving forwards.

N      Neutral. The engine  may be started in this position.

D      Drive. To be  used  for all normal driving conditions.
        All three gears are used in sequence and the best gear for prevailing conditions is 
        automatically selected. At town speeds a part throttle downshift operates under load  
        to prevent the engine labouring in a high gear. Beyond the normal full throttle position, 
        heavier pressure activates the kickdown facility causing the transmission to downshift 
        into the most suitable gear for maximum performance when overtaking. In this position the 
        engines full rev range will be used.   
        At town speeds, full throttle will engage 2nd gear for brisk acceleration while kickdown 
        pressure will engage 1st for really rapid overtaking. Those used to other less responsive 
        transmissions may be surprised by this eagerness of response and learn to adjust their 
        throttle usage accordingly.

2      Manual Second. In this position the normal upward shift into 3rd does not occur. It can be 
        used for extra engine braking (taking care not to overspeed the engine) or to prevent 
        overfrequent automatic shifting where the driver is transferring repeatedly from power to 
        No performance improvement is gained by delaying the 2-3 upshift manually. In this position 
        1st gear is used as normal where appropriate.

1      Manual First. Engages 1st gear to provide increased power at low speeds and extra engine         One of the 25 Schuler converted 'Super Ranger' approved by LR
        braking. An inhibitor prevents engagement until road speed is reduced to safe levels but 
        care must be taken not to overspeed the engine once the gear is engaged. In an emergency 
        the speed inhibitor can be overridden to engage 1st at speed by briefly pushing the 
        accelerator pedal to its kickdown position then releasing. 
        It should be stressed that this must only be used in a dire emergency (total brake failure at 
        below 50 m.p.h. for example) as it will cause severe stress and possible damage to the 
        gearbox and driveline.

NOTE   The above general comments also apply in low range although speeds in the gears are 
severely limited and shifts will be firmer. Delicate use of the accelerator is recommended.
Manual selection for engine braking off road should be made well in advance of requirements.

For low range instructions see below.


GENERAL - The five speed Range Rover offers all the advantages of vehicle control of the        Typical Range Rover from Wood & Pickett with Schuler FF transmission.
normal manual control with the addition of a slick, sporting gearchange and a high fifth gear for   Most probably between 1-2000 Schuler transmisions were installed in RR
cruising. It should be noted that new maximum speeds in the intermediate gears apply, these 

        1st          31 m.p.h.
        2nd         50 m.p.h.
        3rd          75 m.p.h.
        4th        104 m.p.h.


To assist gear-changing there is a spring bias into the 3rd/4th plane. To engage reverse slap 
lever sharply across to the left and then forwards.


To change from high to low, or low to high:

1         Stop vehicle.

2         Apply handbrake.

3     a) Automatic - select P on auto selector.
       b) Manual     - select neutral on main gearlever.
                                                                                                                                                  Jensen FF and other carmakers used a similiar, but slightly different
4         Move transfer gear lever smartly and firmly to desired range. If a delay is made in neutral       Ferguson Formula system produced of GKN - in Range Rover the 
           the shift may not be accomplished. In this case the engine must be switched off before         Schuler Presses Ferguson Formula transmission was produced of
           attempting to complete the shift.                                                                                        Schuler-Voith.

           Low range would normally only be required in severe 'off-road' conditions, i.e. deep mud 
           or sand or very steep hills. Low/low should always be used when descending off-road 
           steep hills. When in doubt use low range off-road.


A  -  Automatic
B  -  5-Speed JRT Manual (Jaguar Rover Triumph)

1    A    WEEKLY

            Check automatic transmission fluid level. The dipstick/filler tube is located at the rear 
            of the engine compartment close to the bulkhead on the vehicles right hand side. The 
            oil level should be up to the high mark on the dipstick with the engine idling and the 
            gear selector in neutral. 
            Topping-up requires Mopar, Dexron, Dexron II or equivalent.
            Any persistent loss of fluid must be investigated.


            Check transfer gearbox oil level. The combined filler/ level plug and also the drain plug 
            are situated in the rear-facing wall of the main casing and both should be carefully 
            cleaned before refitting.

            Filling must be carried out slowly to achieve the correct level. Automatic transmission 
            fluid must be used. (If ATF is not available, any S.A.E. 10 engine oil may be used in an 
            emergency, but the unit should be drained and refilled with the correct oil at the earliest 

3.         EVERY 6,000 MILES

a)   A    Check automatic gearbox fluid level as in point 1 above.

b)   B    Check 5-speed gearbox fluid level. The oil level should be up to the bottom of the filler 
            Topping up fluid should be as per Jaguar/Rover/Triumph recommendations for this unit.

c)  A/B  Check transfer gearbox fluid level as in paragraph above. 
            Not only should a lack of fluid be investigated but also an excess of fluid which may 
            indicate an internal fluid migration which requires rectification.

d)  A/B  Check centre diff operation. Apply handbrake and leave gear lever in neutral. Chock 
            the wheel diagonally opposite to that being jacked up. Jack one front wheel clear of              Schuler-Voith Ferguson Fomula transfer case - clearly seen badge
            the ground. If this wheel is stiff to turn the viscous coupling unit is functioning correctly. 

            If the wheel will not rotate either the front axle or the 4 wheel drive unit is at fault. If 
            the wheel rotates freely the viscous coupling unit is at fault.

            If the wheel turns freely, and the front drive-line is all intact, it means that the V.C. 
            unit is not functioning correctly, in this case contact Schuler Presses Limited.

e)   A    Check automatic gearbox shift performance. Test shift speeds against those shown 
            The transfer box sprocket ratio is shown next to the serial number on the rearward 
            face of the transfer gearbox. 

            If the gearbox shift points are not as shown below follow the rectification
            procedure outlined. 
            Cable adjustment can be carried out (after removing the engine air filter) using
            the threaded portion of the outer cable. To raise line pressures and shift speeds, 
            tighten cable. A slack cable will cause clutch and band slip giving premature failure 
            of the unit. 
            If the kickdown cable fails the vehicle must not be driven.

f)  A/B   The whole transmission should be visually examined for oil leaks. Advice for 
            rectification can be obtained from Schuler Presses Limited. 
            No attempt to carry out warranty work should be made without prior authorisation 
            from Schuler Presses Limited.

                                                                                                                                                       Larger picture of the number #488 Schuler FF transmission 

1.        With the accelerator in the kickdown position and the transmission selector lever in 'D', 
           full throttle downshifts should be available up to speeds shown below.

            Change of gear                                               Sprocket ratio
                                                              1.16:1                1.08:1                1:1
            3 - 2                                         56-66 mph          60-71 mph         65-77 mph
                                                         (90-106 kmh)      (96-114 kmh)      (104-123 kmh)

            2 - 1                                         24-29 mph          26-32 mph         28-34 mph
                                                           (38-46 kmh)       (42-51 kmh)        (45-54 kmh)

            Adjust throttle valve cable to minimum tension at which these downshifts are obtained 
            and then tighten 1 turn.

2.         Allow car to gather speed downhill with throttle closed and transmission selector lever 
            in 'D'. Upshifts should occur at speeds shown below.

            Change of gear        .                                        Sprocket ratio
                                                              1.16:1                 1.08:1                 1:1
            1 - 2                                        8-13 mph             9-14 mph         10-15 mph
                                                        (13-21 kmh)          (14-22 kmh)      (16-24 kmh)

            2 - 3                                       12-17 mph            13-18 mph        14-20 mph
                                                        (19-27 kmh)           (21-29 kmh)      (22-32 kmh)

            Part throttle shifts should be comparable in terms of smoothness with conventional 

            If the vehicle does not pass the above test, check:

            a) That basic engine tune is satisfactory.                                                                           Inside view of the transfer case - visible with the morse-chain drive
            b) Carburettor butterflies are fully open at kickdown position.
            c) Throttle valve lever is getting full travel of 54 ±3°.
            d) Throttle valve return spring is fitted and functioning correctly.
            e) Transmission oil level is correct.

            On completion of road test the adjustment of the gear selector must be rechecked. If 
            it does not correspond in every position exactly with the detents on the automatic box 
            early transmission failure will result.


1.         Engine Failure
            In an emergency a car equipped with automatic transmission may be towed safely 
            with the high/low selector lever in neutral and the automatic selector in 'P' without the 
            need to disconnect the front or rear propshaft.

            Similarly manual gearbox cars may be towed with the high/low selector lever in 
            neutral and the main manual gearbox in 4th gear.

2.         Front Axle Failure

            Tow with rear propeller shaft removed and front end pick-up.
                                                                                                                                                   The viscous lamels shown in this demonstration cut-out 37/63-ratio
3.          Rear Axle Failure

            Tow with front propeller shaft removed and rear end pick-up.

4.          Failure of Transmission or 4-W-D Unit, or doors locked and transmission in gear

            Tow with either:-

a)         Rear propeller shaft removed and front end pick-up


b)          Front propeller shaft removed and rear end pick-up,


c)          Both propeller shafts removed with/without pick-up.

5.          Roller Rig Operation

             Due to the integral limited-slip centre differential a special  purpose 4 wheel drive 
             roller rig must be used.

TNS/LAW                                                                                                                                  The Schuler-Voith FF seen from the upper side with hand-brake drum