john lewis

...We’ve tackled what is probably toward the more adventurous side for a weekend warrior, shade tree mechanic; installation of lockers in the "white mule" 87 Range Rover. You say "No Way! This job needs to be done by an expert!" Well, I have to agree that it is best to have a pro do the work, however, if you are careful, make an assumption in the set-up (more about this later), and are willing to take a bit of risk, it can be done by the experienced Do-It Yourself’er. I’ve done several and have never had a problem.  I do have to say though, that as with all tech work, it's at your own risk.  Don't take for granted that anything is correct, because I could be wrong, or the manual followed could have been wrong.  If nothing else, if you have the work done by a qualified mechanic then I hope that this column will tell a bit about what is involved in the job.

WHY LOCKERS?

First, why lockers? Don’t Land Rovers already have a locking center differential? Well, yes, but that locks the front and rear driveshafts. Your Landie has 2 more differentials, one in each axle and these are open. Sooo, if you get into a spot where one wheel on each axle loses traction they are going to spin and you’re stuck. Thanks to the terrific articulation in Land Rovers this doesn’t happen too often but there are still those times such as when that articulation is exceeded, or when you’re on a loose surface. In that situation if you are locked front, rear, and center, it only takes one wheel with traction to pull you through. For those who insist that Land Rovers are so good that they have no needed for added locking devices, poppycock – adding one or a pair of lockers will just make an already excellent off-roader into a superior one.

Second, don’t lockers put a strain on the drivetrain? Well, yes and no. True, lockers will put power to the wheel that has traction and when locked the drivetrain can be under more load. However, consider the times that you’ve had a wheel hopping, grabbing for a bit of grip, drivetrain clunking and clanking as traction is gained and lost. This is where you snap axles or shear splines. Also there are many cases where you would need to rely on momentum to get over tricky situation, where, with lockers you could just touch the gas gently and crawl over. Driven intelligently, in many situations lockers can reduce the shocks compared to an unlocked Rover. As icing on the cake, a locker will also is allow you to take a line that is less risk to expensive body panels, rather than one that optimizes traction.

Why didn’t Land Rover put lockers in standard? Well, first, the excellent suspension takes care of most situations so they aren’t as necessary as in lesser vehicles. Adding lockers would add to the cost, and since most owners don’t make use of their Land Rover’s full potential anyway it’s better to leave them out. Most important, lockers can add some small, but noticeable difference in handling and an occasional noises. To the expert these little clicks and clacks are the music of machinery functioning, but to the novice who doesn’t know what a locker is it can be an annoyance that brings them to the dealer to fix something that isn’t broken.

OK, so you are already exceeding the Land Rover’s traction capability and want more. Traditionally the selection here in the States has been limited to a manually operated unit. However we also have a choice of the excellent Detroit and TrueTrac lockers from TracTech. Unlike the ARB which allows the user to lock and unlock as needed, and requires active driver input to do so, the Detroits lock and unlock automatically on demand.

The rear Detroit No Spin locker is a new version of the traditional Detroit, with most of the bumps and clanks removed. It is a positive locker in that it definitely locks up solidly when it sees a significant difference in speed between the two axles. I remember the days of Detroit-equipped Mustangs clunking and clanking around every turn. Going into the project I had fears of such an outcome for my civilized Range Rover. I shouldn’t have worried. But more on that later.

The front True Trac is a gear-drive locker which partially transfers power to the wheel with traction. However, unlike the old limited slips it does not use clutch packs which are prone to wear out. Using the geared action it transmits considerably more traction than the old clutch units.

INSTALLATION

Big question, can the average DIY’er install lockers in the garage? Well, my garage is so crammed full of old automotive and motorcycle junk that these were installed outside in the driveway. If you can install, say, a camshaft or new clutch, then you should be able to do the lockers yourself. The tricky part is setting back-lash which requires a commonly available dial indicator to do properly.

Note, I am not a professional mechanic, so take this information only as a journal of what worked for me, not as instructions of what you should do.  There is risk of injury, risk of damaging components, and risk of causing an accident if parts fail while driving.   If you don't feel comfortable doing it yourself, have a qualified rear-end specialist do the work for you.

REAR LOCKER

Ok, enough talk, let’s get on with it. Before commencing with the actual job it’s a good idea to give the axle a good cleaning a day or so before to remove all the gunk and dust that may fall into the housing when it’s opened up. Also, this is one of those jobs that absolutely requires the use of the shop manual specific to your vehicle. Following are some of the basics, but follow the shop manual as you go, and be sure to use the appropriate thread locker when called for.

Starting at about noon on Saturday the gear oil was drained, rear wheels removed, and axle shafts pulled. Have a rag handy as some gear lube will be trapped in the axle ends and will drip out.

For safety the rear wheels re-installed so the vehicle could be left on solid ground for the job. Driveshaft is then unbolted at the rear and held up out of the way with safety wire. Bolts holding the differential are removed, and the differential housing pulled out. This is tricky as you must clear the self-leveler, but if you go slowly you will find that there is a position that will clear everything. Best to put a good thick pad on the ground as the "pumpkin" is heavy, and after your arm gives out it’s nice to have some padding underneath. Be REALLY careful here, good place to dislocate something or bash a finger!

LOCKER SET-UP

Lug the differential assembly up to the bench and find a way to prop it upright. Lacking the fancy stand used by the dealer I came up with my own custom fixture, Folgers part no 22348. It’s available at most supermarkets and as a bonus it comes conveniently packed with just over 2 lbs of coffee.

Follow the Rover manual to remove the old differential unit and then the ring gear. Since the old bolts have threadlocker on them, nice to have an air wrench for this. Next, oil and install the new bearings which are included with the Detroits, . You can press the bearings on, or lacking a press, I selected the appropriate size big socket and VERY carefully tapped them on. The bearing is a tight fit - one slip here and you’ve junked it. (it's been a couple years now, but as I recall, I put the bearings in the freezer overnight so they'd go in more easily)  

After bearings are installed, re-install the ring gear. Use threadlocker and follow torque specs to the letter. Note that the manual includes instructions for assembling the pieces into the differential carrier. Turns out that some non-Rover versions of the locker are sold as components to install in your old carrier and the standard instruction sheet includes info on this too which can be a bit confusing. Fortunately, the Rover units are sold pre-assembled and ready to install.

Following the Rover manual, place the assembly into the housing. Note that the ring gear and pinion are matched and have matching numbers etched on them. You MUST keep them matched up. Install the assembled ring gear and check the run-out. Finally, set the backlash / pre-load adjustment as specified using a dial indicator. Good news is that the Rovers have a bit looser tolerance than most vehicles so set-up does not have to be quite as precise. Allow about 1 hour to get backlash / pre-load set, as it will probably take several tries to make sure. After getting everything set-up you should rotate the gear a few times and test backlash at several positions, just to be sure. Now, you’re done.

Here’s that one big assumption and a caution. You will note that no mention was made of setting the pinion angle as described in the manual. Since the pinion was not changed, and the same ring gear was installed, the pinion angle SHOULD not have changed. This may be a big assumption, but in doing a number of differentials over the years I have never had a problem. If you feel the least bit squeemish about this part of the job though, no problem, take the assembly down to your local driveline shop and they can do the set-up for you, for much less than the whole job would have run.

With the differential done, just re-install in the axle housing in reverse order you took apart. Unless you lift weights regularly it’s going to be a real pain to get the differential lifted back up with one arm. It’s especially bad since by now it’s probably getting toward the end of the day and you’re dirty and tired anyway, and you have some careful maneuvering to do. It can be done, but caution those nearby that some creative language may come from under the car. Button everything back up with new gaskets, replace Castrol gear lube, and you’re locked. If all’s gone well you still have enough daylight to take a quick test drive and be back in time for a nice dinner.

THE FRONT

Well, rear wasn’t so bad, was it? Now, on to the front. Because of the steering at this end there are lots more pieces to remove and re-install. Given that the rear does probably 70% of the job when climbing it’s tempting stop right there. Odds are that one of the three wheels will maintain traction. However, if you off-road regularly or seriously, adding the front is definitely worth the extra effort.

First step as with the rear is to drain the gear lube and remove the axles. Pull the wheels and make sure the vehicle is safely supported by strong jack stands. Now, remove the little stub axle. The brake calipers must be removed and these should be wired up out of the way so there is no strain on the brake lines. Next, remove the big nuts on the stub shaft ends and pull the brake rotor off. Make certain that the bearings are kept clean and the seals don’t get nicked. If your brake rotors are showing lots of wear as they typically will by 60-100K miles, now’s the time to replace them. Even if you don’t need to replace rotors you should replace the brake pads rather than re-installing the old ones. Finally, remove the bolts holding the axle flange on and pull that, noting how everything is located. At last, you can remove the front drive shaft, complete with CV joints. Inspect the CV joints for wear carefully.

From under the vehicle, as you did with the rear unbolt the drive shaft. One problem now is that the tie-rod and steering dampener assembly is in the way and to remove them you must remove the tie-rod ends which can be a real chore and frequently results in trashed parts. Here’s a little trick that will make this part of the job a snap. (and alone will re-pay you the cost of the first couple years subscriptions! – ed.) Loosen the nut on the tie rod end a couple turns and squirt some penetrating oil in. Next, put the jack under the tie rod end bolt and jack up slightly so that all the weight is just barely on it. Rap the SIDE of the steering arm with a hammer. Chances are it will pop free after 4-5 hits, but if not, get a second hammer and hit from both sides simultaneously. What you’re doing is setting up vibrations in the steering arm and using the weight of the vehicle to push it out. With this trick it’s no longer necessary to resort to damaging heat or hammer blows that destroy threads. Be careful as the vehicle will jerk as it comes free, so make sure that it won’t fall off the stands or onto something.

With the tie rod and dampener removed, unbolt the differential housing and set-up exactly the same as with the rear, although this time you are installing the smaller True Trac unit.

Re-install everything per the manual, again, using threadlocker where called for. Be very careful when installing the cv joint and axle flange to be sure that everything is correctly positioned as it goes in. If your swivel ball seals are leaking now is the time to replace them too as it’s just another hour or so to do both.

Also, in theory if you have not touched the setting on the tie rod, the wheels should be aligned, but it is still a good idea to drop by an alignment shop for a check of the toe-in.

Again, I'm no professional mechanic, so take this information only as a journal of what worked for me, not as instructions of what you should do.  There is risk of injury, risk of damaging components, and risk of causing an accident if parts fail while driving.   If you don't feel comfortable doing it yourself, have a qualified rear-end specialist do the work for you.

OFF-ROAD RESULTS

The day before installation I had to find a good reference test. Just about 2 miles from my driveway there’s a small piece of BLM land with an ideal test hill, comprised of loose shale and firm rock, with crazy articulation and an impossible stair step at the top. I had never been able to make it over that last stair challenge. In the name of scientific evaluation I aired down and had one more go at it, and sure enough, it was still as impossible as ever. That was Friday night.

Then, Saturday evening with rear locker only I tackled that same hill again. Got to the stair step, and with tires howling in protest and a couple tense moments we cleared the top! YES! The hill had been conquered, and without having to resort to axle busting momentum to get over.

Going back Sunday evening after installing the front, the improvement was again almost as dramatic. This time the top step was cleared with hardly a protest from the tires at all. Complete control at all times. Then I realized that this time I had forgotten to air down! The rear Detroit and front TrueTrac definitely make difficult obstacles much easier, and minimize the need for parts breaking momentum to get through.

ON-ROAD BEHAVIOR

OK, so lockers are great off the road but how about those stories about horrible noises and weird handling on the road. I can assure you that the clunks and clanks of the old Detroits are a thing of the past. Most I heard from the rear end was an occasional click and with rear locker only I could not detect any handling difference driving on pavement.

Fronts were not quite as transparent, but not bad. First, the locker manual says that with the front tires off the ground you should be able to spin one tire freely, and the other should rotate in the opposite direction. Not so, and I spent the night worrying about having to pull the front axle apart again. In the morning a call was placed to Trac Tech to find an answer. Seems that they figured that any one driving a Land Rover would probably really be using the locker, more than with many other vehicles. With that assumption they designed in some pre-load so there would be some friction even with the wheels off the ground. This eliminates the need for a light application of the brake to provide friction to the spinning wheel and allow the other to get traction, a trick the factory locked Hummer driver must use when a wheel lifts. Because of the pre-load there is some friction between axles all the time, and there will be a slight feel. Not bad, but it is there, about similar to many of the higher powered front wheel drive cars I’ve driven.

One caution though is that if you have other suspension or steering problems already the locker will amplify them. I knew that my near 200k mile power steering pump was very weak and the front locker made the problem more noticeable. A new pump quickly solved that. Also, what had been a moderate pull at highway speeds became more pronounced. Turned out to be a tire problem with my abused BFGs. Again, once fixed everything was fine. The front locker really can’t be blamed because if I had fixed the problems that I knew were already there, there would have been no problems at all. Equal tire diameters and tire inflation are important, otherwise the locker will try to correct for the different rotation speeds.

We were fortunate to have some rain, and it was with some trepidation that I ventured out on our oil-slicked LA roads. Turned out that the lockers were again transparent. No problems at all. Unfortunately it will be some months before we have some meaningful snow in the mountains so an ice and snow test will have to wait for a future issue. The final test though came the following weekend when my wife borrowed the car for the day. I didn’t mention anything about possible differences with the lockers, and after a day on LA freeways and side streets she returned and couldn’t remember anything different in the way it drove.

"DETROIT" / TRUETRAC COMBO vs. MANUAL LOCKERS

I’ve spent many, many days off-road in my Series and other vehicles equipped with manual lockers, and the comparison between the two was inevitable. At every hard-core off-road event, there is always some campfire talk about automatic vs manual, locker vs "limited" slip, and which one works best where. From my time spent with both, here’s my 2 cents.

The manual lockers such as the ARB are completely open when turned off, and locked when turned on. This does offer an advantage in some situations, but this requires active participation from the driver to get the most from them. To be honest I can’t count how many times, at the end of a long day in 100+ heat, that I’ve forgotten to lock or unlock when needed. I’ve also had some problems with broken switches and cut wires and have had friends with problems with air lines, but more careful routing would have avoided that.

On the other hand, the Detroits are completely automatic. You don’t have to think and maybe more important, if a friend or your spouse takes over, they don’t have to go through a training session on when to flick switches on and off. My wife who is not an off-roader would never consider touching the ARB switches, but I have no hesitation to have her jump in the Detroit-equipped Range Rover now.

Cost-wise the Detroits are considerably less expensive than the ARBs. Even forgetting the cost of the compressor which you need for tire inflation anyway, the Detroit and True Trac unit cost is less, they include new bearings, and installation cost is less. If you are performing the work yourself, then the installation takes less time since there is no need to locate switches, route wires and hoses, and drill your differential housing.

After we get a few off-road miles under our belts, watch these pages in an upcoming issue for a more direct and in-depth comparison between the two.

CONCLUSION

Lockers of any kind will make a dramatic difference in the off-road performance, even on the already superior Land Rover products. Yes, an experienced DIY’er can do the installation at home, with some assumptions and some risk in the set-up. Or, there is the option to take the differential to the local shop to have the installation done, and still save. As for the Detroits? They work automatically and transparently all the time, on and off-road, and since they are completely automatic and don’t need extra wires or hoses to operate they are simple to use lower cost to buy and install, and their presence is hardly noticed on the road. The Detroits definitely get two thumbs up!

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