Thread: There has got to be a way to lock these diffs

Hey Julian,

Thank you for taking my call earlier to erase some of the confusion surrounding the type of differential fitted to the L322 Range Rovers, I hope the text and pictures provide some assistance.

Further to our conversation:

Front Differential

The front differential is mounted on the LH side of the vehicle sump. The sump has a cast tube through it, which allows for the fitment of the RH drive shaft and separates the engine oil from the differential oil. The differential unit is secured to the engine sump with 4 bolts. The bolts pass through lugs in the differential casing and are secured into threaded holes in the sump. An O-ring seal is fitted to the casing and locates in the sump to provide a seal between the casing and the sump.

The casing comprises two halves with machined mating faces. When assembled, the iron casing halves are sealed with a thin film of Loctite 574 sealant and secured together with twelve bolts. The LH casing is the carrier for all the rotating parts and the RH casing is a cover to close the unit and a support for the RH carrier bearing. A breather tube is fitted to the casings. This allows a plastic tube to be fitted and routed to a high point in the engine compartment, preventing the ingress of water when the vehicle is wading.

The LH casing is fitted with a drain plug and a filler/level plug. The level plug allows the unit to be filled with oil until it leaks from the filler hole, ensuring the correct quantity of oil is added. The differential unit contains approximately 0.8 litre of oil for a dry fill and requires approximately 0.75 litre if oil is changed due to residual oil retained in the casings. The differential is a conventional design using a hypoid gear layout. This employs a hypoid bevel pinion gear and crown wheel, with the pinion offset below the centre line of the crown wheel. This design allows for a larger pinion gear to be used which has the advantages of increased gear strength and reduced operating noise.

The front differential is available in two ratios. V8 engine vehicles use a differential with a final drive ratio of 3.73:1 and Td6 engine vehicles use a final drive ratio of 4.10:1. The ratio is changed by changing the amount of teeth between the crown wheel drive gear and pinion gear. Therefore for a ratio of 4.10:1, the crown wheel drive gear will have 4.10 times more teeth than the pinion gear. This equates to the crown wheel drive gear having 41 teeth and the pinion gear having 10 teeth.



Break Down

The front differential comprises a pinion shaft and hypoid bevel gear, a crown wheel drive gear with an integral cage which houses two planet gears. Two sun wheels are also located in the cage and pass the rotational drive to the drive shaft shafts.

The pinion shaft is mounted on two opposed taper roller bearings with a collapsable spacer located between them. The spacer is used to hold the bearings in alignment and also collapses under the pressure applied to the pinion nut. This allows the nut to be tightened to a predetermined torque, which collapses the spacer, setting the correct bearing preload.

The pinion shaft has an externally splined outer end which accepts and locates the input flange, which is retained by the pinion nut. The opposite end of the output flange has an internal spline which provides positive location for the front propeller shaft. The flange has an external O-ring seal which seals against the front propeller shaft shroud preventing the ingress of dirt and moisture into the splines. An oil seal is pressed into the LH casing and seals the input flange to the differential unit. The pinion shaft has a hypoid bevel gear at its inner end which mates with the crown wheel drive gear.

The crown wheel drive gear is located on the carrier and secured with ten screws. The carrier is mounted on taper roller bearings located in each casing half. The bearings are press fitted into the casing and a spacer is located on the outside face to apply preload to the bearing.

The carrier is fitted with a shaft onto which the two planet gears are mounted. The shaft is secured in the carrier with a roll pin. The sun wheels are located in pockets within the carrier and mesh with the planet gears. Curved plates are located between the carrier and the sun wheels and hold the sun wheels in mesh with the planet gears. Each sun wheel has a machined, splined, bore to accept the drive shaft. A groove is machined in the bore to locate the snapring fitted to the drive shaft, providing positive drive shaft location.



Rear Differential

The rear differential is located centrally in the rear subframe. The front of the differential is attached to the subframe via rubber bushes and bolts. The rear of the differential is mounted to the subframe via a single, offset rubber bush and a bolt.

The casing comprises two parts. The pinion housing is made from cast iron and provides locations for all the internal components. The pinion housing is sealed at the rear by an aluminium casting which is secured to the pinion housing with eight bolts and spring washers. A gasket between the two casings seals the unit. The rear cover has cast fins which assist heat dissipation. A breather tube is fitted to the rear cover. This allows a plastic tube to be fitted and routed to a high point under the vehicle body, preventing the ingress of water when the vehicle is wading.

The rear cover contains an oil level plug which allows for oil filling and level checking, with the differential installed in the vehicle. The level plug allows the unit to be filled with oil until it leaks from the filler hole, ensuring the correct quantity of oil is added. The differential unit contains approximately 1.2 litres of oil from a dry fill. If oil is being replaced, a smaller quantity of oil will be required due to residual oil retained in the pinion housing.

The differential is a conventional design using a hypoid gear layout, similar to the front differential. The rear differential is available in two ratios. V8 engine vehicles use a differential with a final drive ratio of 3.73:1 and Td6 engine vehicles use a final drive ratio of 4.10:1. The ratio is changed by changing the amount of teeth between the crown wheel drive gear and pinion gear. Therefore for a ratio of 4.10:1, the crown wheel drive gear will have 4.10 times more teeth than the pinion gear. This equates to the crown wheel drive gear having 41 teeth and the pinion gear having 10 teeth.


Break Down

The Rear differential comprises a pinion shaft and spiral bevel pinion gear and a crown wheel drive gear with an integral cage which houses two planet gears. Two sun wheels are also located in the cage and pass the rotational drive to the drive shafts.

The pinion shaft is mounted on two opposed taper roller bearings, with a collapsable spacer located between them. The spacer is used to hold the bearings in alignment and also collapses under the pressure applied to the pinion flanged nut. This allows the flanged nut to be tightened to a predetermined torque, which collapses the spacer, setting the correct bearing preload.

The pinion shaft has an externally splined outer end which accepts and locates the input flange, which is retained by the pinion nut. The output flange has six threaded holes and mates with the rear propeller shaft. Six bolts secure the rear propeller shaft to the input flange. An oil seal is pressed into the pinion housing and seals the input flange to the pinion housing. The pinion shaft has a spiral bevel gear at its inner end which mates with the crown wheel drive gear.

The crown wheel drive gear is located on the carrier and secured with ten screws. The carrier is mounted on taper roller bearings located in machined bores on each side of the pinion housing. The bearings are retained in the casing by a circlip, the thickness of which is selected to apply the correct bearing preload.

The carrier has a through hole which provides location for the shaft. The shaft provides the mounting for the planet gears in the carrier cage. The shaft is fitted with a snap ring at one end which locates in a machined groove in the carrier, locking the shaft in position.

The sun wheels are located in pockets in the carrier cage and mesh with the planet gears. Spacers are fitted between the sun wheels and the carrier and set the correct mesh contact between the planet gears and the sun wheels. Each sun wheel has a machined bore with internal splines and machined groove near the splined end. The groove provides positive location for a snap ring fitted to the end of each output flange. Each output flange has a splined shaft which located in each sun wheel. A snap ring fitted to the splined shaft locates in the groove the sun wheel bore and positively located the output flange.

Oil seals are pressed into each side of the pinion housing and seal the output flange to the housing. Each output flange has six threaded holes which provide for the attachment of the rear drive shafts. The rear cover is located on the rear of the pinion housing and is sealed to the housing with a gasket and secured with eight bolts.



As can be seen from the following operation description it operates as a standard open differential.

Differential Operation

The operating principles of the front and rear differentials are the same. Rotational input from the propeller shaft is passed via the input flange to the pinion shaft and pinion gear. The angles of the pinion gear to the crown wheel drive gear moves the rotational direction through 90°.

The transferred rotational motion is now passed to the crown wheel drive gear, which in turn rotates the carrier. The shaft, which is secured to the carrier also rotates at the same speed as the carrier. The planet gears, which are
mounted on the shaft, also rotate with the carrier. In turn, the planet gears transfer their rotational motion to the left and right hand sun wheels, rotating the drive shafts.

When the vehicle is moving in a forward direction, the torque applied through the differential to each sun wheel is equal. In this condition both drive shafts rotate at the same speed. The planet gears do not rotate and effectively lock the sun wheels to the carrier.

If the vehicle is turning, the outer wheel will be forced to rotate faster than the inner wheel by having a greater distance to travel. The differential senses the torque difference between the sun wheels. The planet gears rotate on their axes to allow the outer wheel to rotate faster than the inner one.



Hope this helps, if you need me to chase up anything further please do not hesitate to contact me,

Regards,

Jonathon Stapels
From: Julian Patane [mailto:julian.patane@harrop.com.au]
Sent: Wednesday, 27 August 2014 7:47 AM
To: Jonathon Stapels
Subject: RE: E Locker for 2002-2006 L322 Range Rover

Hi Jonathon

Unfortunately cannot integrate it due to the traction control system being integrated into the elocker component of the vehicle.

Regards,

Julian Patane | Customer Service Coordinator
Harrop Performance Products
96 Bell Street, Preston, Melbourne, Victoria, 3072, Australia
t: +61 3 9474 0900 | f: +61 3 9474 0999
e: julian.patane@harrop.com.au | w: HARROP | Engineering Performance Since 1955





From: Jonathon Stapels [mailto:Jonathon.stapels@live.co.uk]
Sent: Monday, 25 August 2014 5:35 PM
To: Julian Patane
Subject: RE: E Locker for 2002-2006 L322 Range Rover

Hey Julian,

I really appreciate you answering my questions so far, however, I have just one more.

The E locker you mentioned was only available on selected models from mid 2005. For the earlier L322 Range Rovers without the factory E locker differential it possible to integrate a Harrop Eaton locker in to the rear diff?

Regards,


Jonathon Stapels

Be very interested in what reply you get this time .

The other option , Although not easy, is a diff swap. Maybe a Commodore diff with a Harrop E-Locker or some thing similar.

Originally Posted by 33chinacars

The other option , Although not easy, is a diff swap. Maybe a Commodore diff with a Harrop E-Locker or some thing similar.

Or put D3 front and rear diffs in and put ARB air lockers in.

Garry

Surely the crown wheel pinion and diff centre are the same as in some other diff as AFAIK Land Rover don't make diffs but buy them in.

Maybe compare the centres to a couple of other cars eg D3 X5 MB to see if they are similar before making a conclusion . The first I would look at is X5 seeing BMW owned them then.
Regards Philip A

I just had a look at the exploded views atc. The diffs are in my limited experience unusual as the crown wheel faces the sun gears whereas in a conventional diff the crownwheel is on the other side. See if any other cars have the crownwheel like that.

This is an X5 front diff 2000-2006 . It looks to be similar in construction to the L322 diff. I looked at some other images of later smart locking diffs ( which I wonder as the same as the D3-4 locking diff) and the crown wheel is in the same orientation as the L322.
Maybe it's a starting point.
Regards Philip A

I am still confused to the need for lockers in an l322 when the traction control has the same affect as a locked diff?
I have not yet had the instance where I have been stuck with a wheel in the air spinning, requiring the use of a locker.

Drive it like a range rover and it will get you out like a range rover.

Originally Posted by chaybra

I am still confused to the need for lockers in an l322 when the traction control has the same affect as a locked diff?

Hmmm no - if that were the case then LR would not offer the e-diff option in the Disco/RRS range.

With a diff lock both wheels on an axle set are driving - with traction control, when it is activating, drive is only to one wheel on an axle set as the other wheel is braked.

Garry

Originally Posted by PhilipA

Surely the crown wheel pinion and diff centre are the same as in some other diff as AFAIK Land Rover don't make diffs but buy them in.

Maybe compare the centres to a couple of other cars eg D3 X5 MB to see if they are similar before making a conclusion . The first I would look at is X5 seeing BMW owned them then.

That is a good idea. ARB engineers have told me that the ford ranger front diff is 'almost identical' to the d3 and d4 front. Except the ranger gets a steel case which should make it stronger or at least longer lasting.