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Discussion Starter · #1 ·
First off I apologize I have no photos. I'll try to describe the processes well enough to figure out without visuals.

I've been in isolation for more than a week and decided I'd address some electrical niggles on the 164. Chief among these was slow, sticky windows. Painfully slow in cold weather. I know a thing or two about electric motors so I figured I'd take a crack at fixing the issue rather than spending money on new regulators.

(the same procedure applies to fixing any brushed electric motor - I've done the same on my intermittent seat motors, and I've fixed audio equipment using these techniques)


Tools needed:
Quarter inch ratchet with 10mm socket and a ~6 inch extension
Phillips screw driver
Thin flat plastic scraper (I use a Bondo scraper)
Side cutters
Fine tip tweezers you can spread open to around 1.5-2 inches wide
1/8 inch rubber tube and a small syringe or funnel that fits it

Zip ties
3 in 1 Oil or a good gun oil (I use Lucas)
Deoxit spray
Thick motor oil or gear oil (ie 75w90)
A hell of a lot of patience and about 8+ hours to kill

First step is to remove the window motors. This isn't easy the first time around, but it's totally doable without removing the glass or regulator from the door. You'll need to strip the door cards off the inside. Also remove the top inside "weather" strip, the black plastic trim that separates the glass from the top of the door card. You don't need it off to deal with the motors, but you will to lubricate the track. Leave the window fully up.

Now the fun part. Look for a series of 10mm head locknuts over rubber isolator bushes. They hold the regulator in the door. You only need to remove ONE, which secures the top of the motor. It will be near the middle-top portion of the door, all by its lonesome, with a three nut cluster ahead of it holding the worm gear.

Now you have to fish your arm into the door through the holes cut at the bottom of the door skin. Feel around and you'll grab a cylindrical metal object with a pair of wires coming out of the side. That's the motor we want to extract.

It's held to the gear drive with two 10 mm head bolts. Using a quarter inch ratchet with a 6 inch extension you can undo these bolts. It's not easy, but it isn't impossible. You will be working blind so take your time.

Once those two bolts are out push the stud through the door (the one you removed the nut from) and the motor will pop free. It is keyed to a rubber damper that is in turn keyed to the gear drive. You want that to stay in the gear assembly, but it might come loose inside the housing. Here again, you will be working blind, but make sure it is pressed in place and doesn't fall out. If it does it's pretty fiddly to realign with the key and push back into place, but again not impossible.

Now you'll have to trace the wiring back to the connector at the lower rear corner of the door. It's a black two-wire connector with light blue/gray wires. You'll need to snip three or four zip ties that secure the loom to the door. Note the position of the wire and the zip ties, as you'll need to redo this.

Now you can fish the motor out. Repeat three more times if you want to do all of them. Note that the motors are left and right handed, but are the same front to rear. So you can interchange the front and rear, but not left and right.

Retreat to the comfort of your workbench. This will be relaxing compared to the blind, knuckle-skinning fight you just completed.

The motor body is held to the flange with a pair of Phillips screws. Later ones MIGHT have rivets from pictures I've seen. If you have rivets it's going to suck as you'll have to drill them out and replace them afterwards.

Undo the screws. Don't pull it apart yet. On the keyed shaft that sticks out the top there is a C clip. Pop that off, then gently pry the plastic washer off that's underneath (it's a tight fit and it is fragile, so be gentle).

Now you can separate the halves. Mark the casing so you don't flip the flange 180 degrees on reassembly (it's hard to do because the wire routing prevents it, but if you did the motor will run backwards). You'll need to feed the wires through the body a few inches to get enough clearance to pull it apart, as the wires are attached to the flange. You don't need to remove them completely, just push them through enough to pull the guts out.

The top has the brush assembly and wiring, the casing has the permanent magnets, and the bit in the middle is what we are working on. Once you pull it apart the brushes will pop out under spring pressure but won't go flying so don't worry about those yet.

You'll note a dark black streak on the commutator, the smaller diameter coil that interacts with the carbon brushes. This is what you are fixing. Carbon transfer from the brushes builds up on the commutator over time and reduces the efficiency of the motor. We need to get that clean.

I use Deoxit and Q-tips which works well on most buildup. I had one motor that was particularly stubborn that I gently buffed with a scotchbrite pad. Get it as close to bare metal as you can, but if you are using scotchbrite be careful not to remove material!

Clean the tips of the brushes as well. Keep going until your Q-tips come back clean. You'll be surprised how much black gunk will come off.

The motor is suspended on two pivots, one in the bottom the casing below the magnets, one through the middle of the flange. Clean these surfaces and lubricate generously with the 3 in 1 oil.

Now reassemble - the easiest way I found to get the brushes back into position is to spread open fine tipped tweezers to push both sides back into their slots, then lower the commutator into place before removing the tweezers and letting them snap back into position. Make sure they do snap back and seat against the commutator.

Replace the washer and C clip on the shaft to keep the unit together while you slide the guts back into the casing. If you don't the magnets will suck the armature into the casing and yank the commutator out of the brushes.

Put the guts back in gently, pulling the wires back through as you go. Make sure it spins freely with minimal drag before you bolt it back together. Also don't overtorque the screws, it can cause the shaft to bind. Pull the black rubber grommet through until it pops back into the hole in the casing to seal it.

IF you thought getting these motors OUT was hard, wait until you have to put them back. "Reassembly is the reverse of disassembly, with added profanity"

The key to getting them back in is aligning the key in the shaft to the hole in the rubber damper. This isn't fun, working blind through a couple of holes in a door panel. It's hard to feel when it's popped into place, but it will sit a little more flush and you can rotate the motor back and forth and feel it being held in place. You'll need to hold it here while you slip the two 10mm bolts back in. I find it easiest to pop the stud back through the door to hold the motor in place while doing this. It will not stay in place on its own, fair warning so you don't let it go and have it immediately fall out forcing you back to square one.

BEFORE PROCEEDING: Put everything together finger tight, plug in the motor, then turn the car on and verify the motor is working and the window moves. If the motor spins but the window doesn't move then you haven't got the shaft aligned properly, or the rubber damper has popped out of place. If this is the case, get your rage out of the way then try again.

Now tighten everything down, reroute the wiring, and put new zip ties on to hold the loom.

Before putting the door cards back on, we need to lubricate the window track. It's a single C-shaped channel in the middle of the door running top to bottom. Remember we removed the trim strip earlier? With it out of the way, look inside the door between the inside and the glass. Tada, you can see the top of that channel. Lower the window to the bottom, then take the 1/8 rubber tube and stick it into the top of that channel. Use the syringe/funnel to pour a few tablespoons of oil into the channel, giving it a few minutes to run down the length and get everything nicely lube-rick-ated. Then turn on the car and run the window fully up and down a dozen times. Revel in how much faster and smoother it is performing, provided you did everything correctly. I take no responsibility if you didn't.

Now you can reassemble the door card. Use the plastic scraper to slip the vinyl of the top of the door back into the trim strip.

Now swear you will never, EVER do this ungodly job again. But enjoy your functioning windows and all the money you saved by doing it yourself without buying any parts.

1,132 Posts
LOL I thought you were stuck at home and were going to give us some tips on speeding up our PCs.
i.e. Windows 10 :D

667 Posts
I just removed, repaired and reinstalled the driver's side front window regulator on my '91 164S. It wasn't that horrible a job, took me an easy afternoon, but this time I knew what I was doing because I HAD DONE THE GODDAMN JOB TWICE BEFORE. There, I feel better now.
Seriously, the task totally sucks the first time (like doing a clutch and/or brake master cylinder on a Fiat X1/9), but after a couple of times it's pretty easy. No doubt it's the learning curve that allows professional mechanics to make a decent living and not go insane.

2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
17,388 Posts
Yup. Figuring out just how to manipulate the cable mechanism so that it can be removed out the hole in the door insides takes a while. Took a long while for me the first time (pretty much used up my curse word vocabulary), and of course, I end up not remembering how to do it the next time. When I do remember, can take only about an hour all told from start to finish.

And, the failures I have had are the big plastic gear inside breaking teeth off, not the motor. Have lots of good motors, lol.

667 Posts
The mechanism can only exit the door panel one way, through the opening at the forward lower corner, where on my car the stereo speaker lives. So, remove the speaker first. My latest failure was self-induced and pretty stupid: At a McD's drive-through I hung one of those cheap plastic cupholders on the door panel just to the left of the steering wheel, with the window still rolled up. Then I hit the window switch, and the plastic tab on the cupholder (that slides inside the window opening) hung up on the inner rubber/felt gasket that's glued to the inner door panel, and pulled the front of that gasket down, jamming the window instantly. Instead of quitting at that point, I did my best Florida Man imitation andI kept trying to lower the window, which it did, but then wouldn't raise all the way afterwards.

Turns out the sudden jam had caused the regulator cable to jump off the lower pulley, so I had to mess around with the mechanism for a few hours to get everything back on track. I also slathered bearing grease liberally on all the moving parts after reassembly. It all works fine again, except that there is some graunching noise from the cable, most likely it got kinked in a couple of spots during the trauma so isn't sliding smoothly through its housing anymore.

By the way, this is one of the famous "Latvian" regulators from eBay, actually an OEM-quality product, that came with a Magnetti Marelli motor that works considerably faster than the OEM ("Electro-Products"? or something like that) motor of the original regulator. Not sure if the Latvian vendor is still around, but I hope so because his prices (and shipping cost) were very reasonable and the regulators are becoming unobtanium.

Premium Member
6,682 Posts
I can have the entire regulator out on any door in the LS in 15 minutes. Easier to take the whole thing out and work on the bench
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