WINDOW LIFT MOTORS - REBUILD GUIDE
Lotus window motors are pretty unique. They were manufactured by Delco in UK. They have 10 teeth and 18 mm diameter gear wheel, which is much smaller than any Jaguar, (22 mm) gear wheel. The gear wheel diameter is always small, 18mm, (or 23/32"). It is extremely difficult to adapt any Jag motors, because gear wheel/ratio mismatch, so it is more practical to rebuild your old motors.
Typical Motor Failure Mode:
In most cases, the armature does not burn out. Something else fails: brushes, magnets, circuit breaker, contacts, etc.
1. Usually, the glue holding permanent magnets to the housing fails. High humidity and high temperatures cause parts separation. Loose magnets grab the armature slowing down or immobilizing the motor. Current overload trips the safety breaker inside the motor every time the window switch is activated. Flexible contact inside the breaker capsule cycles excessively, overheats and bends out of the factory preset position. Motor "acts" dead, but it may just need a simple repair or adjustment.
To disassemble the motor, unscrew two torx head screws and gently separate can from the gear box. Do not force the parts. Pull the armature and check windings for continuity using a good eye and moving coil ohm-meter (non-digital), or simply a test light. If any one winding is burned out, buy used Delco motor and swap the armature. Hang-on to the original gear box, since it has a pretty unique bolt pattern, back spacing and gear wheel.
Clean the can inside with (good chlorinated, flammable) Brake or Carburetor Cleaner fluid. Mark the desired magnet position (depth, distance from the flange, etc.), with a marker. Use plenty of "miracle" Gorilla Glue (thick Cyanoacrylate), to re-attach magnets, one at the time. This glue cures very fast and there is no time for magnet re-positioning, so a steady hand is a must. Let it cure for a couple of hours, preferably - overnight.
Before you proceed to the next step, get yourself some good magnifying goggles.
2. If motor stops working after one second or half way trough the lift cycle (you can hear "cycling" clicks), you'll need to rebuild/recalibrate the overload capsule (internal circuit breaker). The most tedious part of the job is opening the bi-metallic breaker capsule. It looks like a 3/8" x ¾" copper box located at the side of the brush holder. It has two crimped edges with a double sided sticky foam tape between the flanges, which acts as an isolator. You should hold the capsule with the pliers and use a thin stubby knife or jeweler’s screwdriver to pry the crimped edges half- way open. Take your time. Using flat nose mini pliers, bend one of the flanges bit further, almost to 90 deg position. I had to grind one side of the pliers jaw to thin out its profile. Be gentle, do not shred the adhesive tape, (it acts as an isolator between two halves of the capsule).
Next, insert a very thin pin or blade (Exacto knife w/ sharp point) between capsule lower half and the tape, gently pry it open and separate the upper shell from the base. Be careful not to hurt the tape! Capsule will open like an oyster shell.
Once you get it open, clean the contacts and bend upward the bi-metallic strip of metal with the contact button attached. Use the jeweler's thin blade screwdriver to do that. You have to use your "best judgment" how much to bend it. Do not mess with the silver-ish strip since that is a bi-metallic element. Close the capsule. You don't have to bend capsule flanges back. The tape will hold it together. Also, it will be easier to work with the capsule in the future, should you need further adjustments.
(*) Now, you can insert the armature. First, using a thin pin or dental pick, pull both arms of the brush springs away from the axis of the commutator and rest them on the edge of the plastic housing, just above the slot. Next, push brushes outboard into the housing to clear the commutator. Apply hi-temp, hi-Molybdenum or graphite grease over the rear end & the worm gear, and insert the armature by screwing it into the gear box until it bottoms out. Push the brush spring ends down until they snap into the slots pushing brushes toward the stator. Rotate the armature clockwise by hand to verify that brush blocks contact the stator. Next, holding the gear tight, slide the motor can w/ magnets over the armature. If you don’t hold on to the gear tightly, magnets will pull the armature out of the gear box and beyond the brush blocks. Ooops, and you will have to start all over again, (go back to *).
Additionally, I have replaced the regular (burn-out) window fuses at the fuse perch (fuse # 30 & #34
), with automatic 20A contact breakers (cost $5 in NAPA store). This gives you an additional protection in case you have over-bent the strip inside of the motor capsule/breaker.
When done with this repair, before you install the door moisture barrier, it is a good practice to install an additional plastic "bib" or apron over the top of the gear case and the motor to deflect any water entering door cavity.
Addition of a relay circuit modification and extra grounding wires from the motor mounting screw to the beam will increase longevity of your switches.
>>> Warning: do not keep the ignition in "ON" position for any prolonged period of time!!! Your ignition coil will burn out in 3-5 minutes
P.S. To remove the motor/actuator arm assembly, there is a need to drill an access hole in the door inner shell, see picture in post #129
. You'll need it for inserting a socket+extension to remove the motor lower mounting bolt.