Front
Differential Emergency Field Recovery (Range Rover III)
Introduction
1. Replacement with Spare Custom Driveshaft
2. Replacement with Spare Parts or AB Coupling
Upgrade Kit
3. Bailing Wire Reattachment Methods
4. Welding
5. Making and/or Carrying your Own Replacement
Driveshaft
6.
Locking the Center Differential?
Overcoming ECU Reaction to Failure
Driving Out
Reporting the Problem When You Get Home
More Information
Photo courtesy of
British Pacific: Land Rover's Manual for Africa (BP Part
number
SMR684MI). Might come in handy when repairing the RR
III front diff in the field! Available at this
link.
Introduction
To date, as far as I know nobody has managed to recover from front
diff failure without a tow truck. Unfortunately, many of us (like me)
use our Range Rovers off road far out of reach of
Land Rover's roadside service, and hundreds of miles from the nearest
dealer. Pondering the very real possibility of being stranded far
from help, I thought some ideas on possible field recovery methods
might be some help.
Caveat: I realize
these are extreme measures -- try them at
your own
risk!! If you "fix" the problem temporarily and it fails again
on the
way home, you are at risk of a dangerous situation such as front
wheel lockup.
With that caveat, here are a couple of ideas that might
get you out to the paved road where you can call a tow truck. I realize
most of them sound funky and desperate, and I may be accused of making
light of what is essentially a very difficult subject, but necessity is
the mother of invention, and who knows what some resourceful owner will
come up with. If you have tried these or any other alternative
solutions, please email me
so we can share
your experience with other owners.
1. Replacement with Spare Custom
Driveshaft
This option has just become available as of this writing (November
2006) and is the most practical and certain I have heard so far. A
custom driveline shop in San Leandro Californis (Rover 3 Driveline Center) has just come
out with a replacement front driveshaft that can simply be bolted into
place if your front diff splines get mashed up. The custom shaft
includes U joints at both ends as the Land Rover genuine one should
have in the first place to avoid this whole problem. Carrying a spare
driveshaft is actually fairly practical (Series Land Rover owners
routinely carry spare axles on expeditions), and replacement is fairly
straightforward. Also, you have the advantage that the replacement
gives a permanent solution to the problem. The only trouble is that you
will probably also need a new diff input drive flange because its
splines seem to give way more than those on the on the shaft end. If
anyone finds the input flange or tube as a separate part, please email me so we can post it
here, as this would become practical as an emergency repair by carrying
the flange plus the replacement driveshaft. Accordingly, this is a
repair that is best carried out before you leave home!
See the RR III Replacement Front
Driveshaft Page
for more details.
2. Replacement with Spare Parts or AB Coupling
Upgrade Kit
If cost and weight are no object, an extra front diff and driveshaft
could be carried as spares. I found the complete front diff assembly
(part number TBB000043) is
now available from Atlantic British
for $695 (see photo at right courtesy of Atlantic British).
They also have the complete front driveshaft (part number TVB500290G)
for $159, and the rubber O ring seal for $2.95.
If you can round up a the input drive tube for the
diff (labeled "8" in the diagram below at
left), carrying this
alone might give you a fair chance of driving out of the boonies
unscathed. My speculation on this is based on the fact that the failure
of the splines usually seems to be more complete on the inside of the
drive flange/tube than on the end of the shaft (see the pictures on the
main diff failure page. Carrying the drive
tube or flange plus a spare driveshaft would be even better.
In spring 2008, Atlantic British
came up with a replacement
input tube as part of a new Coupling
Upgrade Kit. Their new tube
is machined from # 4340 steel alloy
that is heat-treated, resulting in a more durable design that should
last
longer than the inferior genuine coupling. Their 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 very handy repair kit to carry along on those remote
expeditions! (Photo at left courtesy
of Atlantic British).
Removal of the
drive tube is covered in the shop manual, under Oil Seal -- Pinion".
First you remove the front propeller shaft (drive shatf) and then hold
the tube still (LR recommends a special tool but you could use a pipe
wrench) while undoing the pinion nut ("9"
in the diagram below left). Then the task is to pull the drive tube off
-- for this, Land Rover recommends special tool 99-500A which looks
like a simple gear puller. It is hard to tell what part of the drive
tube
it gets a grip on, but it must be the lip near the rear end
of the tube. Most likely, an ordinary gear puller would work just as
well. If you have trouble you might be able to clamp something on to
the outside of the tube to grip on -- eg a hose clip or C clamp.
The resulting
partial repair
of the diff is not covered in the shop manual as it is not approved by
Land Rover (they warn that the bearing preload may be disrupted leading
to premature failure of the diff. But that would be no worse than the
situation we are already in!!) So study the way the diff is put
together and
carry appropriate tools!
|
|
Side cross-section of front
diff, with splined input drive tube (labeled "8") at right.
Illustration from official Land Rover Technical Service Bulletin.
|
Front driveshaft (propeller
shaft). Rear end has flexible coupling, but splined front end at lower
left (protected by a collar) engages directly with differential input
drive tube. Ilustration from official Land Rover Technical Service
Bulletin.
|
3. Bailing Wire Reattachment Methods
A real backwoods solution would be to try and reattach the
driveshaft rigidly so that drive is restored to the front diff. How you
go about it would depend on how much of the mechanism is still intact
and what tools you have available. Ideally, if everything is still in
place and the splines are just chewed off, it might be possible to
drill through the entire diff input tube and drive shaft and put a
strong pin or bolt through it to lock it in place.
More likely to be feasible in the field would be to just drill through
the diff drive tube and into the collar surrounding the driveshaft
splines, and putting in bolts, sheetmetal screws or whatever you have
available. Of course this theory relies on the said collar still being
more or less intact, and firmly attached to the driveshaft. (I am not
sure how strong it is). If you did this in multiple places around the
circumference of the shaft, it might have a chance of holding til you
get out to the pavement. The chances would be increaed if you could
drill at least partly into the driveshaft itself in each place. You can
get an idea of what would need to be done from the pictures on this
page.
If access is too difficult (see photo below right), you could
disassemble
the driveshaft and remove the diff input drive tube from the diff
-- it might be possible to do this by undoing the pinion nut ("9" in
the diagram above). Then, with everything laid out in front of you,
insert the driveshaft into the input drive tube and drill away. Marking
the position of the components before disassembly would be a good
idea so the finished length will be right when you come to reassemble
it.
To enhance the chances of
these methods, it would clearly be desirable
to carry a drill, and some short bolts and a thread tappping kit, or
failing that some self-tapping metal screws.
Photo at right:
View of front driveshaft/propeller shaft coupled to front diff input
tube on author's Range Rover prior to replacement. The collar at the
front end of the driveshaft, partly covering
the
diff input tube, is clearly visible.
4. Welding
Quite a few four wheelers carry welding equipment. In a real emergency
you can even make a welder using two or three car batteries in series.
This might be possible, for example, if like me you carry a jump start
battery and/or you have installed a back-up battery in the vehicle as
several RR III owners have -- see the battery backup installation
page. You would have to disconnect the batterise from the vehicle and
hook them up in series. See this
link for a practical treatise on this subject. Welding ability
could open up the following possibilities:
A. Welding the remains of the driveshaft directly to the diff input
tube might work, but I am skeptical whether the repair would last more
than a few minutes due to the flexing of the joint that caused
the splines to fail in the first place. Another problem with this
approach, if it does work, is how to disassemble it for permanent
repair when you get back to civilization!!
B. More promising would be to fashion a crude flexible coupling for the
front of the driveshaft. This might be done, for example, by carrying a
spare flexible coupling and two of the "flexible coupling
adaptor" part shown in the driveshaft diagram above right. (The
driveshaft flex joint assembly TIJ000012G is available from Atlantic British
for $47.95). Measure
carefully, saw off the driveshaft to the right length, and weld one of
the adaptors to it. Weld the other adaptor to the diff input tube.
Assemble with 6 bolts as for the rear flexible coupling. In my opinion,
this method probably has the most chance of success if no spare diff
parts are available.
5. Making and/or Carrying your Own
Replacement Driveshaft
Following on from the idea in 4B above, if you are handy
with
metalworking techniques it should be possible to weld
up your own emergency replacement driveshaft, coupling and diff input
tube
ahead of time in the luxury of your shop at home. Then you could carry
the spare knowing you are truly prepared.
Better yet, have a drive shaft shop make one up for you! Rover3
Driveshafts of San Leandro, CA has done just that --their redesigned
shaft has flexible couplings both front and rear to prevent a
recurrence. See the replacement driveshaft
page. If you take this route, you are better off installing it
before the old shaft and diff fail, because the trouble is that the
splines in the diff input tube seem to wear faster than those on the
shaft.
If you do take this approach,
please be sure to email me
so we can share your experience with fellow owners. With any luck, the
replacement
will be better than stock, and installing it at home would prevent the
whole problem from occuring!
Photo: Replacement
driveshaft from Rover3 Driveshafts.
6. Locking the Center Differential?
A more desperate approach might be to remove the driveshaft all
together and try to lock up the transfer case center differential so
the vehicle's computers will not know the front drive is disconnected.
One possibility
might be to remove the Torsen diff cover plate bolts one at a time and
inject some high-friction goo into the works to gum it up!!
Another possibility might be to lock up the front output of the
transfer case by other means so it is -- eg bolting a liece of scrap
metal to the flexible coupling so it is jammed against the case body or
the subframe. In theory all the torque should then be transferred to
the rear wheels, although theywould then turn twice as fast as they
should for a given engine speed, and the Torsen differential would be
constantly workingas well, probably ewearing itself out in short order.
A more serious problem with this method may be that the vehicle's
electronics might well detect this and shut things down!
If you can figure out a way of implementing either of these methods,
please email me!!
Overcoming the ECU Reaction to
Failure
If a mechanical repair can be successfully effected, there is
still the question of whether the vehicle's Mother Hen computer systems
will let you drive it. In an ideal world, when the driveshaft is
reconnected the computer will
recognize that everything is normal again, and let the car be driven.
However, past Range Rover electronic systems have been designed so they
go into a "Hard Fault" mode when something like this happens, and the
fault cannot be cleared without the dealer's TestBook/T4 diagnostic
system. If this is the case, all our efforts at mechanical repairs are
in vain unless you are willing to carry a Rovacom Lite or equivalent
with you (see Diagnostic Scanners page).
If you have experience with this problem please email me so we can share
your insights with other owners!
Driving out to the Pavement or Repair
Facility
If you have used solutions 1 or 2 above, and if the ECU does not
prevent it byimmobilizing everything, you should be able to drive out
to civilization at full speed with impunity. However, if you have
succeeded in getting the vehicle running again with one of the
band-aid solutions in sections 3-6 above, it goes without saying that
you should drive very
carefully, placing as little strain on the repair as possible. Putting
the tranny in manual mode and using a higher gear might help reduce the
torque being sent to the drivetrain.
When you get to pavement, it wold be advisable to stop and call a tow
truck. If you do insist on risking driving on the highway with a
jury-rigged repair, go very slow, as another failure will force a
sudden stop, and may do something as bad as locking the front wheels so
you lose control completely.
Reporting the Problem When You Get
Home
When you do get home, don't forget to report the problem to the
appropriate government agency that deals with vehicle defets and
recalls. If even a few people do this it is likely to start the
investigation process that will lead to Land Rover designing a real
solution and instituting a recall campaign. If you live in the US,
these defects should be reported to the National
Highway and Transportation Safety Administration (NHTSA).
More Information
RR III Replacement Front Driveshaft Page
Front Differential Problems and Solutions Page
Front Diff Failure Section of
RR III Common Symptoms and Fixes page
Alldata: Source of Range Rover
Technical Service Bulletins (subscription required)
NHTSA
Link for reporting safety-related defects
Range Rover III Forum: Do a
search for "diff" to read about owner experiences.
Emergency
Welding using Automotive Batteries -- by our friends in the Toyota
fraternity!
If you have tried these or any other alternative solutions, please email me so we can share
your experience with other owners. .