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Series Land Rovers

Repairing Wiper Motors

Origional Author: Alan J. Richer (OVLR)
Having just had the unmitigated pleasure of reworking the wiper motors on my Series IIa 109 pickup, I've decided to pull the lessons learned in this process together into a tutorial for those fortunate souls who haven't had this pleasure... if that's what you want to call it.

First off, this applies to the Lucas motors used on Series II and IIa vehicles. These are the newer motors with the rounded casings. The older motors, with their squared-off casings, from what I am told are mechanically similar but I haven't had one apart to check this personally, so beware.

Secondly, any road vehicle must have functional windshield wipers. This means that they have to be on the truck and working or the local constabulary can and will pull you over and ban your vehicle from the road for this. If you're going to rework your motors, plan on doing the job in one sitting if at all possible.

On to the show, then....

1: Dismounting the motor from the truck:

The motors on my car were held in place by a double-nut on a threaded shaft. Two of these were used to mount each motor, and both were badly corroded on my example. The threaded shafts ended up unscrewing from the motors, and are being replaced with the proper thread of stainless-steel bolt. With the wiper blade removed by loosening the mounting bolt and pulling it off the shaft, the motor was free to be withdrawn into the cab.

I got off relatively unscathed in this process. I have heard of cases where the wiper mount, motor and windscreen have corroded themselves into an immovable mess, and one case where a windscreen had to be scrapped because the corroded hardware could not be removed (Hi, Dixon!). Replacement parts for the mounting bits are available, but make sure to protect the wiper shaft if you have to resort to force in removing the motor.

Take care with it and expect to use penetrating oil and persuasion if yours are badly corroded. Also, for your own peace of mind, expect to replace the mounting studs. They can be easily fabricated from stainless-steel threaded stock, or barring that, cut-down bolts of the proper size.

The two wires on the motor were then disconnected, noting the respective terminals they attached to. Pay attention here, as one of the terminals is mounted o the motor shell (and as such is grounded to the chassis).

NOTE: For those of us thinking of converting positive ground cars to negative ground, these motors work quite well with either polarity grounded. They turn the same way with either polarity to the shell of the motor.

2: Disassembling the motor for cleaning:

Once on the bench, I ran each motor with a 12-volt power supply. Both dragged badly, indicating that the gear grease had congealed.
I removed the rear cover of the motor by removing the brass slotted nut at the center of the blade control and the two machine screws at the left and right sides of the rear cover. After this, the rear cover was free to come off, only needing a bit of persuasion with a plastic mallet to come free.

Removal of the front cover was a bit more involved. The first item to be removed was a small metal block trough which the wiper shaft passed. With this block removed, the shaft spring could be released by straightening a crimped washer holding the wiper shaft in the motor. Straightening this removed the tension from the locking spring for the shaft, allowing it to slide back out through the motor. Instead of the crimped washer, I am told that some of the motors have a circlip fitted into the groove. Either way, disassembly doesn't change, but be careful not to lose the clip if so equipped. With this fastener out, the three nuts holding the front cover on can be removed.

3: Motor cleanup and check-out:

Once you get to this point, your first reaction is going to be disgust at the condition and amount of filthy, pasty grease that is all over the inside of the gear case. That is precisely why we're here, as this grease is causing many problems and must be renewed.

Before we disassemble anything, let's have a good look at what we're disassembling. Looking at the gearcase end, the first thing you'll see is a 110-pitch gear drilled with an offset bearing. In that bearing is the pin from a shaft that runs to a follower arm with a hole down its center. This is the bit that the wiper shaft comes out of.

Under the 110-pitch gear is a double gear, which engages both the edge of the 110-pitch gear and the motor shaft. This intermediate gear is made of phenolic and, I am told, can disintegrate if the motor is abused with heavy loads. The motor shaft runs through the central casting into the back half, where the windings, rotor and switching are.

What I'll be detailing here is a general cleanup/greasing/inspection. This cleared up 99% of the problems on both my motors, and seems like the favorite mode of failure for this design.

If, however, once you clean up the grease and such and the motor still runs slowly or not at all, then you may have an electrical fault in the rotor or commutate coil. The repair of these is beyond the scope of this article, but it can be done by an electric motor shop if replacement parts are not available.

If this is the case, though, check the brushes for proper contact and look for broken wires and similar problems. This could also be the problem, and could still be an easy fix.

Now comes the fun bit, where we get REALLY dirty. Fill a small container with grease solvent - personally I like the newer orange-based stuff, as it's friendlier to the environment and my lungs. Whatever you do, don't use acetone or any cleaner that might be unfriendly to the electrical insulation on the wiring. If you can't get the orange-based cleaner, I have it on good authority that WD-40 will remove the grease without removing the wire insulation. (Hi again, Dixon!)

Working carefully, remove the gears from the front of the motor and clean them in the solvent, using a toothbrush to get out the stubborn bits of gunk from the gearteeth. DON'T soak the fiber gear for an extended period - it WILL have problems if you do. Also clean the pins that are on the shaft to the follower arm of accumulated crud.

Also, get a cotton swab into the bearing holes in the casting and clean them out to eliminate the old grease completely.

We want to remove the follower arm from the casting to give it a good cleaning inside and out. if yours are like mine, the edges of the back of the hollow shaft are mushroomed, stopping it from sliding out. In this case CAREFULLY file away the burrs and work the shaft out of the bearings.

DON'T FORCE IT OUT! You'll eat the bearings. Clean the inside hollow of the shaft with solvent, as well as the inside of the bearings the hollow shaft rode in. Use a cotton swab with solvent, being careful to keep the solvent off the electrical bits.

The motor rotor's the next bit we want to deal with. Its two bronze bushings need to be cleaned and re greased. This part is tricky - If you don't feel comfortable after reading it through, then skip it if the rotor turns freely and runs OK.

Remove the two nuts holding the rear bearing in place. It will slide up the motor shaft, and the carbon brushes will disengage from the copper contacts. WATCH OUT FOR THE BRUSHES! If yours is like mine, they will be slung forcefully out of the motor, landing several feet away. If lost, don't panic. Most hardware stores can provide brushes for small power tools that can be made to serve nicely with a bit of filing. As a matter of fact, I've replaced the brushes in both my motors anyway, as they were badly worn.

Pivot the rear bearing assembly out of the way, being careful of the wires from the brushes to the coil below. If you're comfortable with soldering, it's much easier to simply disconnect the coil wires from the rear bearing assembly, noting which went where.

With this, the rotor can be withdrawn from the stator. Clean its bearing surfaces with solvent, also the bearings themselves.

4: Reassembly:

First thing to go back in is the motor rotor. Grease its bearing surfaces with a good coat of an all-purpose grease, and reinsert it into the hole in the stator.

Fitting the rear bearing is a bit involved. You need to hold the brushes open with the points of a needle nose pliers and slide the bearing back over the rear rotor shaft, being careful of the attached wires at all times. This is where removing the coil wires pays off, as you can slip the assembly back on much easier if you don't have the 3- dimensional motion restriction of the wires.

It's easier if you present the bearing assembly so that the end of the rotor shaft can slip straight back into the bearing - hold it straight! It seems tricky, but it can be done! At worst tie the brushes back with a bit of wire so you can devote both hands to engaging the shaft. Reattach the rear bearing with the two nuts removed earlier and tighten. If you removed the coil wires or broke one off, now is the time to re solder them.

Now, grease the bearings of each of the gears and put them back in place in the front of the casting. The fiber gear goes in first, then the 110-pitch gear, then reinsert the hollow shaft you took out earlier, making sure to grease all of the bearings and pivot points as you put it back together.

    You might want to make very sure that the lubricant you use has proper cold-weather characteristics. Some all-purpose lubricants congeal in cold weather, making the operation of the wipers very difficult. I personally used a silicon-based lubricant called Syl-Glide, as it advertised constant viscosity at colder temperatures, and up as high as +400F. Remember, these motors are going to take some pretty nasty temperature extremes sitting there in the sun, so be careful with the lubricants you choose.

Once you have all of the bits back in properly, turn the rotor of the motor by hand to make sure nothing's binding. If all's well, put the front gearcase cover back on and test-run the motor, either on the bench or off your Rover's battery.

If it passes, great!. Now we can put the wiper shaft back into the motor and complete reassembly. Reinsert the wiper shaft from the rear of the motor. Over the shaft from the front of the motor, slide on the cleaned tension spring and either the washer you removed to free it, or a circlip of the proper size. Personally, I went with the circlips to allow for periodic opening and regreasing of the motors.

5: Remounting:

Remounting the motors is simpler than removing them, as you've already caused all the damage you're going to.... If the mounting rubbers and hardware are in good shape, all you need to do is bolt the motor back on, perhaps smearing a bit of silicone grease on the sealing rubbers where the motor shaft makes contact with them. Also, a little RTV sealant under the aluminum mounting block helps eliminate water leaks at that point. Make sure to clean away the excess, though, for a neat appearance.

If you need to replace the hardware, the cast parts and the rubber gaskets are available from most Rover suppliers. The threaded rods and nuts can be had locally, though, if they're all you need.

Aligning the wiper blades may be a bit tricky, but shouldn't be a problem with a bit of attention to detail. Present the motor to its installation spot on the windscreen with the rear handle in the parked (off) position, then mount and fasten the wiper blade where it should be (pointing to the right while facing the wiper blade from outside the car). This makes sure everyone's in agreement as to the way things need to go when operating.

6: Conclusion:

Cleaning and servicing the wiper motors on your Series II or IIa is a simple, stress-free task that can save you a lot of headaches and money down the road. These small motors are well-built, and with a modicum of service will soldier on reliably in the rain effectively forever.
Copyright Dixon Kenner, 1995-2011. Last modified March 15, 2005.
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