Refurb/Repair power vent window motor assembly

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gbird66
Posts: 70
Joined: Sat Sep 19, 2015 1:12 pm

Refurb/Repair power vent window motor assembly

Post by gbird66 »

I was given a right-hand and left-hand power vent window motor assy out of a 1966 Thunderbird. The complaint on one of them was “poor torque” in one direction. The one stamped “RH” looked like a better candidate, visually, so I chose that one to concentrate on.
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I took an ohm meter and checked both windings (one forward and one reverse) – the reading was a consistent 36 ohms.
It appears that there is a rubberized coating on the motor portion of the assembly; I can only surmise that this was done for either weatherproofing or sound-deadening (or both) reasons.
I decided to peel this off to better access the upper and lower portions of the motor, as well as to disassemble it.
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First, I took off the side access cover which undoubtedly is a worm and sector gear for torque multiplication. Use a 5/16” wrench.
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Here is the inside backing of the plate with the old grease.
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Here is the bevel gear; you’ll notice an e-clip on top of a washer to retain it to the shaft that will drive the open/close gear and tab.
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Use a pair of snap-ring pliers to carefully remove the e-clip.
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Here is the bevel gear with the washer removed. Please note that there is a spacer on the other side of the bevel gear (not shown).
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Here is the worm gear and shaft separated from the motor assembly but still in the part that turns the tab to open and close the vent window.
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Here is the worm gear separated from the closing assembly.
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I wanted to see how freely the gear/closing tab would move through a full range, open to close: It was a bear. I could barely move it with needle-nose pliers, much less regular pliers. I suspect that this might be part of the sluggish/no operation issue.
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I then attempted to pry the gear away from the housing that holds it in place. I did this by carefully going around several parts of the gear by wedging a flat blade screw driver between the side of the gear and the housing and then tapping the screw driver downward with a rubber mallet to see if it would free up a bit.
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This did the trick. I can now move the tab much easier with needle-nose pliers; heck, I can even move the attached gear forward and back with my thumb now.
I used mineral spirits and soaked all of the parts that were just removed. I will come back a little later and use a toothbrush too clean old grease from all parts.
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Now to separate the top of the motor from the base so that we can inspect the brushes, commutator, and windings.
You will remove the two cap nuts at the top of the motor with a 3/8” wrench (shown before rubber coating removed).
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Pull the retaining bolts out of the bottom part of the motor, paying attention to the ground wire eyelet attached to one of the bolts. Then grab the lower portion with one hand and the upper portion and work them apart. This is the top half of the motor can with the field winding/commutator/shaft assembly. Note the ball bearing stuck in the bottom – remember this for later (very important). If you do not see it here, it will be down in the lower portion of the motor can where the rear bronze bearing receiver cup is.
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You now have to separate the windings/shaft assy free of the upper motor can. You can either pull apart by brute force or try and unscrew the shaft from the upper portion. Most likely what will happen is that the bronze bearing race will pull free of the top retainer and retainer plate as shown here. This will have to be rectified later.
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Take a tooth brush soaked in mineral spirits and clean the old grease from the worm section of the main motor shaft.
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Now let’s inspect the commutator. Typical amount of carbon build up. I used a Dremel tool with a stainless wire brush to clean it off. If you do not have a Dremel tool, then emory cloth or very fine grit sandpaper will also work well.
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Now the commutator after being burnished clean.
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Now let’s look at the bottom half of the motor with the magnets and the brushes. Note: I placed the ball bearing I discussed earlier at the bottom to show that that’s where it will go upon reassembly. Judging on the appearance of the brushes, they have a lot of service life left; not unusual when you consider that the motor turns very few revolutions in either direction to open and close the vent window.
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Here the magnet assembly is pulled up and out of the lower can and pulled out of the way to get better access to the brushes; I am going to burnish them with a Dremel tool.
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Here are the surfaces of the brushes after being lightly cleaned up with a Dremel tool. You can use emery cloth or fine grit sandpaper to accomplish the same thing.
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Note I’m also taking a small flat file to clean the contact faces of the motor overload switch.
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I am now going to use CRC Mass Airflow Sensor Cleaner to flush out and loose carbon from the brushes plus any metal filings from the filing of the overload switch contacts. This stuff is excellent: It has great flushing action, evaporates quickly, and will not harm plastics.
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Remember when I pulled the motor windings shaft free of the top cover and the bronze bushing, tension spring, and retainer came loose? We need to tap that into place back in the top cover.
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First, clean out the top cover by soaking it in mineral spirits and wiping or brushing it clean. Then take some bearing grease and place some in the upper hole where the round bronze bushing is going to go.
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Place the round bronze bearing in first.
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Then place the tension spring on top of the bushing, followed by the bearing retaining plate on top the tension spring (retaining plate shown at top right of pic)
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I used a long 21mm socket to tap the items back into the top cover with a rubber mallet but a similar SAE socket would also do.
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Now the (potentially) tricky part. We need to lower the windings/commutator shaft back down into the lower portion of the motor. The brushes must be pulled out of the way or the shaft will not seat all of the way in the bottom. Before we do this, take some 3-IN-1 oil and lubricate the bronze bearing shaft at the bottom. Also don’t forget to place that ball bearing down there as shown earlier. The magnet assembly that was pulled out of the way now must be maneuvered back into position over the top of the bottom of the lower motor can but do not push it in place yet.
I’m going to show you a trick to keep the brushes out of the way so that you may lower the windings/shaft into place.
For the sake of clarity, I have not yet positioned the magnet assembly back into the can so you can see what I did with needle-nose pliers.
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While managing to keep the brushes spread apart, maneuver the magnet assembly over the top, leaving some space for the needle-nose to stay in position. You will then lower the windings/shaft assembly down past the brushes until it bottoms out. Then you can release the pliers.
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Remove the pliers while inspecting to make sure the brushes are resting against the commutator. Once you’ve verified this, you need to maneuver the magnet windings down into the lower motor can. Place some grease on the top of the bevel shaft of the motor then take the top portion of the motor and tap it down using a rubber mallet – making sure the bottom of the motor is resting on a piece of wood.
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You will now take the long motor can retaining bolts that secure the upper and lower motor housings together and insert them through the bottom. Make sure that the top is oriented so there’s a straight shot or the bolts won’t pass through. Also note one of the eyebolts has the ground wire attached.
Once this was done, I took another ohm meter reading of both forward and reverse windings. Remember at the start of the project I measured 36 ohms per winding? My readings are now about 1.1 ohm for each winding
After securing the 3/8” retaing nuts at the top of the motor, I want to power it up in both directions before I do any more assembly. I used a 12 volt car battery charger with a 6 amp setting and attached the negative clamp to the black wire on the motor connector (put a screw in for it to have something to clamp on). I then took the positive clamp and touched it to the red connector wire. The motor ran at at steady speed. I did the same thing to the yellow connector wire (other direction) and the motor ran at a constant speed.
At this point, I believe things are looking good. Now it’s time to reassemble the the bevel gear and shaft that turns the gear that’s attached to the window actuating tab.
I started by packing a liberal amount of grease inside the gear housing.
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Then I inserted the worm gear shaft into the bottom as shown.
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Next the spacer collar goes over the shaft as shown.
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Finally the brass gear on top of the spacer, followed by the washer and secured with the e-clip.
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Place some 3-IN-1 oil on the bronze bushing in the gear housing cover.
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Pack the backside of the gear housing cover with some additional grease.
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Place the gear housing cover over the gear housing.
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Place some 3-IN-1 oil on the end of the gear shaft and then place a liberal amount of grease on the shaft.
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Now place the vent actuating assembly over the shaft, making sure it mates up the gear housing on the motor assembly.
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Secure the vent actuating assembly to the gear housing on the motor assembly with the three 5/16” bolts.
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If all goes well, it should look like this assembled.
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Now it’s time to “get down to brass tacks” and apply power to the motor. While I do have a 12 volt DC bench power supply, it’s only good for about 2 amps – most likely not enough to turn the motor. I grabbed my 12 volt car battery charger which has a 12 volt/6 amp charge setting.
I placed a screw in the black(negative) tab on the motor harness connector; this allows me to clamp the negative battery clamp onto it for testing.
I turned on the charger and touched (very carefully) the red(positive) batter clamp to the middle tab on the motor harness connector. The motor ran and the vent window actuating tab turned and hit the stop. I quickly removed power and did the same thing by then touching the red tab on the motor harness connector with the positive battery clamp and the motor ran and the tab tunred the other way against its stop. I did this several times and it worked well in both directions. Current draw in both directions was a tad under four amps; pretty good I’d say.
Now, the final step will be to replace the rubber coating that was removed to service the motor. I purchased a can of black Plasti-Dip.
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I hung the motor assembly with some trimmer string and placed a towel underneath on the garage floor.
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I then gave the motor two coats of rubber coating, waiting the recommended 30 minutes between coats to dry.
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Here is our completed power vent window motor assembly, coating dry and ready to be placed back into service.
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User avatar
paulr
Posts: 1780
Joined: Mon Nov 05, 2012 12:03 pm
Location: Seattle

Re: Refurb/Repair power vent window motor assembly

Post by paulr »

This is the difference between a legitimate approach to maintenance of these specialized cars, and the hack jobs and Chinese replacement parts that we find scabbed together by so many previous owners. Keep on writing, Gbird! This stuff should be archived.
Paul
VTCI 12014
Registry 45122
'64 Landau HT
"Beer, now there's a temporary solution!" ~Homer Simpson
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wabigoon
Posts: 202
Joined: Sat Jun 15, 2013 12:16 pm

Re: Refurb/Repair power vent window motor assembly

Post by wabigoon »

Great write-up Gbird keep going. Great quality great pics.
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Sierra John
Posts: 147
Joined: Tue Sep 04, 2012 1:01 am
Location: Sierra Madre, Calif.

Re: Refurb/Repair power vent window motor assembly

Post by Sierra John »

Some great information--and photos. Thanks for posting that. I'm sure I'll have to refer to it at some point.
1966 Town Hardtop
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Alan H. Tast
Posts: 3424
Joined: Wed Aug 20, 2003 10:52 pm
Location: Omaha, NE

Re: Refurb/Repair power vent window motor assembly

Post by Alan H. Tast »

I'm impressed! The part that always frustrates me with things like this is keeping the brushes in place during reassembly. This needs to be another Scoop tech article, gbird: you know the drill :mrgreen: .
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
gbird66
Posts: 70
Joined: Sat Sep 19, 2015 1:12 pm

Re: Refurb/Repair power vent window motor assembly

Post by gbird66 »

Alan,

Write up document and pics emailed. Thank you for the kind words and support.

Greg
john6t6
Posts: 448
Joined: Wed Oct 01, 2003 2:42 pm

Re: Refurb/Repair power vent window motor assembly

Post by john6t6 »

Wow, fantastic write up. With the step by step I feel I can tackle this. I bet the motor runs excellent!
Thank you gbird66
1966 Hardtop Sauterne Gold
VTCI #4065
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