Front Differential Problems and Solutions (Range Rover III)


Introduction
Failure Symptoms
Emergency Field Recovery
Underlying Causes
Official Land Rover Efforts to Address Problem
Checking for Misalignment and Wear
Differential Replacement
Aligning the Front Differential
More Permanent Solution: Custom Driveshaft
Prevention Advice to Owners
Reporting Procedure for Diff Failures
Land Rover Customer Service Contacts
NHTSA Investigation (US)
VOSA Investigation (UK)
More Information

Photo: View (looking forward) of front driveshaft and diff on author's 2004 Range Rover. Note diff mounted on left side of engine crankcase/sump, with driveshaft entering it  with no U joint.



Introduction
A front differential would normally be expected to last the life of the vehicle, but on the new Range Rover introduced in 2002 it is a major failure item. At the time of writing (May 2006) there is still no safety recall or redesign of the components involved, although more than one service bulletin has been produced on the subject, and I am getting reports from owners of 2005 models with the same problem. (If you have experienced this failure, please report it to the NHTSA so start the process leading to a redesign and safety recall).

The problem lies in the design of the front driveshaft, which has a no flexible coupling at the front end, so any minor misalignment puts severe stress on the front diff input splines, leading to failure and immobilization of the vehicle. This page is an effort to assemble the known information on this problem and how to solve it.

Failure Symptoms
Of the many owners who have reported front diff failure to me, few if any have had prior warning of the event. One dealer employee reports that an often-missed warning of imminent failure is a loud clunk when changing from drive to reverse and back again. In a notice filed by Land Rover with the NHTSA in March 2005, it is claimed that the premature wear results in "excessive noise".  However I have not heard from any owners that have observed these warning signs. The first you usually know about it is when the front driveshaft generates a loud grinding noise caused by the splines being mangled. The vehicle will not accelerate -- putting your foot on the gas is accompanied by more loud grinding noises. There is a total disabling of the drivetrain. Some owners have reported the vehicle's computers have cut power to the engine. The message center tells you to put the transmission in neutral, and forces you to come to an abrupt stop. When it happens on the freeway, you are lucky if you make it to the side of the road to stop safely. You will have to use the parking brake to stabilize the vehicle once stopped -- shifting into "Park" will not hold it on a slope. I have heard of one case that happened at 80 mph and caused the front wheels to lock, resulting in a loss of control (see this thread on the Range Rover III Forum for this and a sample of other reports; additional ones are described in the front diff section of the RIII common symptoms and causes page).

Quite a few owners have experienced the failure two or three times -- it usually seems to happen at 20 or 30,000 mile intervals. On my 2004 RR, I decided to have the front diff checked at 30,000 miles to make sure it would not fail out in the desert far from help -- even though its May 2004 build date was well after the official fix (see below) was in. Sure enough, the splines were worn out and the diff had to de replaced.

Emergency Field Recovery
See the Diff Failure Emergency Recovery Page for ideas on how to prepare yourself for the possibility of diff failure in the field far from help.

Underlying Causes
The cause of the problem is stress on the front driveshaft and front diff input due to misalignment. To understand this, we need to elucidate the design of the Range Rover III front drive layout. The front differential is mounted on the left side of the engine crankcase, which was strengthened in the design process to accommodate this arrangement. The front diff receives its input from the front driveshaft which comes forward from the transfer case. Because the engine is bolted directly to the transmission, and the transmission to the transfer case, the designers (not unreasonably) must have assumed the whole structure would be perfectly rigid and the usual arrangement of CV joints, U-joints or flexible couplings used on the front driveshafts of lesser 4X4's would not be needed. Mysteriously, they did provide a flexible coupling at the rear end of the driveshaft, where it attaches to the transfer case, but not on the front end where it goes into the diff.

Accordingly, no problems have been reported at the transfer case end, but the connection to the front differential fails far more frequently than it should, often wrecking the entire diff with it. An obvious cure would be to provide some form of flexible coupling at the front end of the driveshaft, but to date (January 2006) I have not heard of any such cure being adopted by Land Rover.

One owner reported the internals of the diff rather than the splines being destroyed.


Official Land Rover Efforts to Address the Problem
When the new Jaguar-derived engines were incorporated in the 2006 model, a CV joint was added at the front as well as the rear of the driveshaft (see photo of front end of driveshaft courtesy of Mark Osen). This was in effect a tacit recognition that the earlier design (omitting any flexible coupling at the front end of the driveshaft) was not satisfactory.

However, the adoption of this improved design for 2006 did not help owners of the earlier 2002-2005 models with the BMW drivetrain, for which Land Rover's official solution to the problem was limited to checking for correct alignment of the front differential. A series of technical bulletins were issued on the matter.

June 2003 Service Bulletin (H121)
In June 2003, shortly after the new vehicle was introduced to the market, a service bulletin (54/03/03) was issued entitled "Front Differential Alignment Process", stating that the required procedure for differential alignment during replacement is not thoroughly covered in the RAVE Workshop Manual. (Amusingly, this made it sound as if front differential replacement was a routine matter). This bulletin said that any damage to the differential drive tube splines requires replacement of the whole front diff as well as the prop shaft. It states "The differential assembly includes a collapsible spacer that determines the bearing preload. There is currently no acceptable procedure for renewing a drive tube in service. If an attempt is made to change the drive tube only, rapid failure of the differential bearings will occur. Damaged or worn splines in the drive tube will have affected the prop shaft, requiring replacement". The service bulletin included a procedure for aligning the new diff. An associated worldwide Land Rover Field Action campaign (ABD121) was evidently implemented to apply this procedure.

May 2004 Service Campaign (SB 121)
In May 2004, a campaign was initiated to check the alignment and wear of the front driveshafts and differential input when owners brought in their RRs for service. Affected vehicles were all "New Range Rover (LM)"  vehicles from  VIN 3A101029 to 4A144905 (i.e. all 2003 and early build 2004 models, with build dates  from 18 April 2002 to 17 June 2003 and 02 July 2003 to 03 July 2003). At the time, parts availability was limited and each dealer was to be provided with only one differential and prop shaft set. Accordingly, some owners reported having to wait some time for their repairs. The parts used for repairs appear to be basically identical to the original parts, although one owner reports the dealer told him they were improved.

Subsequent Developments
In 2005 a steady trickle of owners continued reporting the front diff failures, some for the second time. It was unclear whether the earlier service bulletins had resolved the issue. In November 2005 bulletin 121 was updated and re-issued. The changes were minor, such as incorporating provision for new pre-drilled propeller shafts if replacement is required. The affected vehicle range remained the same, so the official story seems to be that the problem is solved and does not exist on models built after July 3rd, 2003. However, failures continue to occur even on 2005 models.

Interestingly, in March 2005 Land Rover filed a foreign field action report with the NHTSA to report its worldwide campaign back in June 2003 (see above). This was described as a "customer satisfaction" action rather than a defect or safety issue, and the wording made an effort to blame the customer for ignoring the "excessive noise" due to the spline wear that preceded the failures: "Premature wear of front differential splines has been identified on gas and diesel Range Rover. The wear is caused by a misalignment of the front differential to transfer gearbox output flange and results in excessive noise. If the customer does not seek service when symptoms of noise are noticed, or symptoms are ignored, and condition is not corrected, there is potential for failure of these splines that could result in loss of drive". Vehicles affected were still only up to VIN 4A146500 (ie e up to July 2003 build dates). Note use of the word "could" indicating this is a purely hypothetical problem!!

March 2007: Dealer sources unofficially report a huge influx of 2004 models (reaching the 30-40K mileage) coming in with the front diff failure. In the USA, the NHTSA finally started a review of the problem.

Sadly, the official fix seems to be no more than a temporary expedient to get the vehicles past the warranty period in the hope that owners will have to pay for subsequent repairs themselves. The only way around this appears to be to get an NHTSA investigation started in the US (and equivalent actions in other countries) by reporting these failures every time they happen. So, if you have had one in the past, please go to the link and report it.
 

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Checking for Misalignment and Wear
The procedure for checking the front drive shaft and differential are fairly simple, and for vehicles out of warranty might be worthwhile for the owner to do. The process described in the service bulletins basically involves removing the driveshaft, inspecting the splines, reinstalling its front end and wiggling the rear end around to see if its alignment is centered on the output shaft of the transfer case. During the procedure, it is recommended that a hole is drilled into the front end of the drive shaft. There is no explanation of why this was thought to be needed, but it may be to relieve any pressure buildup of the lubricants in the splines. In any case it has proved ineffective. The photos below show what good and bad diff splines look like.

The main steps of the wear and alignment checking procedure are as follows:

1. Jack up and safely support the front of the vehicle. Undo the 6 bolts securing the flexible coupling.
2. Slide the driveshaft forward and remove the coupling. Scribe reference marks on the diff and shaft to aid reassembly, and slide the shaft rearwards to disengage it from the diff. Remove the "O" ring from inside the diff drive tube.
3. Inspect the splines on the drive shaft and inside the differential drive tube for excessive wear.
4. If wear is excessive on the driveshaft, replace it. (30% is excessive).
5. If wear is excessive in the diff input splines, the whole diff has to be replaced. (Note that replacement is not needed if there is only limited wear, spline noise or red fretting corrosion. Alignment of the diff will resolve the noise and limited wear).
6. If re-using the old driveshaft, drill a 5 mm (13/64) hole in the front end of the driveshaft. A fairly long (2.5 inch) hole is needed before you reach the inside of the driveshaft tube, so be careful not to break the drill bit. A lathe is preferable for this operation, but a careful job with a hand drill is OK -- in either case do not let metal shavings remain on the splines afterwards. If replacing the driveshaft, the new part has a hole already drilled in it.
7. To reassemble, align the reference marks on the driveshaft and differential, and reinsert the shaft into the diff input sleeve.
8. Wiggle the rear end of the shaft up and down, measuring its deflection in either direction. If the center point of this slop is more than 1 mm from the center of the transfer case output shaft), the differential needs aligning (see "Aligning the Differential" below). 
9. Remove the driveshaft again, lubricate a new "O" ring, insert it into the drive tube and grease the splines with the approved grease (LR part number TIA500010). Reassemble flexible coupling using new nuts, torqued to 81 lb ft (110 NM). Note -- the November 2005 update no longer requires the O ring renewal.

Differential Replacement
If the spline wear on the inside of the diff input drive tube is excessive, the official procedure is to replace the entire differential assembly. According to the June 2003 service bulletin, the assembly includes a collapsible spacer that determines the bearing preload, and renewal of the drive tube only can apparently result in rapid failure of the differential bearings.

If the input tube and spacer can be obtained from somewhere as separate parts, it is quite likely that an experienced diff shop could disassemble and reassemble the original diff satisfactorily.

Photo at left (courtesy of Atlantic British): New replacement front differential unit with input drive at right side of picture.

Photo at right: Diff removed from vehicle; input tube has stripped splines. 

If the diff does need replacing, the procedure for doing so is fully described in the workshop manual.

Aligning the Differential
If the diff needs realigning, it is a fairly simple matter of loosening the four bolts that mount it to the left side of the engine crankcase, and rotating the diff housing forward or back slightly until the alignment as described above is perfect. The rotation is performed by using the drive shaft as a lever and moving its rear end up or down until the desired alignment is achieved.

When alignment is satisfactory, re-tighten the diff mounting bolts to 81 lb-ft (110 Nm), and re-check the alignment.

Finally, remove the driveshaft, lubricate and reassemble as in step 9 above.

More Permanent Solutions: Custom  Driveshafts and Coupling Upgrade Kits
Several readers have suggested getting a custom driveshaft made by one of the many suppliers who do this for modified Jeeps etc. It is obvious that adding a flexible coupling, U joint or CV joint to the front end of the driveshaft would eliminate the problem permanently.

Finally, such a solution is now available to our readers -- in the US, Rover 3 Drivelines has entered the fray with a high quality custom driveshaft incorporating U joints at both ends. In the UK, GKN can modify the driveshaft to incorporate a front U-joint. For more information see the RR III Replacement Front Driveshaft page.

In spring 2008, Atlantic British came up with some new, stronger parts to prevent recurrence of the driveshaft coupling spline failure. Their replacement Coupling Upgrade Kit features a higher grade coupling machined from # 4340 steel alloy that is heat-treated, resulting in a more durable design that will last longer than the inferior genuine coupling. Each kit includes: a Hardened Steel Shaft Coupling, Lock Nuts, 1.5 oz. Tube PTFE Grease, 2 inch O-Ring, Inner Dust Shield, Dust Shield Removal Tool, Dust Shield Installation Tool and Instructions. Cost is $299 -- a fraction of the usual repair bill for this common failure. This could be a handy repair kit to carry along on those remote expeditions!

Prevention Advice to Owners
In the absence of a redesigned front driveshaft, the most practical solution for owners wishing to avoid this problem is to have the front diff input splines inspected at regular intervals -- probably every 30,000 miles would be appropriate. You will probably have to pay the dealer for the labor to do this -- 1.1 hours is the specified time in Service Bulletin 121 to remove the driveshaft, check for wear, drill the shaft, pack with grease and reassemble. Just removing the shaft, checking the splines, and reassembling should be the work of half an hour. Or, if you are mechanically inclined you can do it yourself (see details of this procedure above). If excessive wear is found, the dealer will probably replace the front diff if your RR is still under warranty. Since the problem is basically one of known defective design you may also be able to persuade them to replace it even if the vehicle is beyond its official warranty period, but you might have to complain higher up the corporate chain.  More information on owners' attempts to get Land Rover to pay for the repair after warranty expiration appears on the Common Symptoms and Fixes page.

Reporting Procedure for Front Diff Failures
Since failure of the front diff results in a complete loss of drive power and therefore can jeopardize safety, US owners who have experienced this problem (even if it was some time ago) should report it to the National Highway and Traffic Safety Administration (NHTSA), in order to get the process started that will lead to a redesign and recall campaign that is our only hope for a real and permanent solution. In the UK, you can file a report with file a report with:
Vehicle Safety Branch, Vehicle and Operator Services Agency, Berkeley House, Croydon Street, Bristol, BS5 ODA.
Tel: 0117-9543300  http://www.vosa.gov.uk, (broadly the UK equivalent of the NHTSA).

NHTSA Investigation
On April 4, 2006, the US National Highway Safety and Transportation Administration (NHTSA) began an investigation into the front diff failure issue. The NHTSA website http://www-odi.nhtsa.dot.gov describes the investigation as follows:

VOSA Investigation (UK)
In December 2007 one of our UK readers received a letter from the Vehicle & Operator Services Agency (VOSA) as a result of his prior complaint to them about his second diff failure. They stated that they had just conducted an investigation during the August-December period to establish whether or not the defect was attributable to a design or construction deficiency, which was liable to cause a significant risk of personal injury or death. Their finding was "inconclusive" as to whether or not such a deficiency exists, but they are now exploring, with Land Rover, whether the performance of this part of the transmission can be improved and expect this exercise to be completed in mid - 2008. Meanwhile, our reporter in the UK encourages any UK owners who have the problem to continue to report it to VOSA (see contact information below)  - the more who report it, the greater the chance of remedial action.

Land Rover Customer Service Contacts
At least one owner has achieved satisfaction by taking his problem to Land Rover Customer Service in the UK:

Land Rover Customer Service Centre on 08705 000 500.
Or write to:
Customer Relationship Centre
Abbey Road
Whitley
Coventry
CV3 4LH
UK
 
More Information
RR III Replacement Front Driveshaft Page
Diff Emergency Field Recovery page: Ideas on how to recover from front diff failure when it happens in the field.
Front Diff Failure Section of RR III Common Symptoms and Fixes page
Alldata: Source of Range Rover Technical Service Bulletins (subscription required)
NHTSA page for filing a complaint about the front diff issue
Range Rover III Forum: Do a search for "diff" to read about owner experiences.

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Page revised February 1, 2012