My '66 Olds big cars have power windows. Which are now solidly 60 years old, so some of the motors are slow, or at least slower than I'd like. What follows should apply to our Oldsmobiles, Cadillacs, Buicks from maybe 1960-1976 or so.

Sometimes window slowness is due to mechanical binding in the regulators, or misalignment of window panes or missing rubber parts. I'll be focusing below on bench servicing the very, very common window motors GM used from the early 60's into at least the mid-70's when they went metric. Shoutout to several YouTuber's who got me going on this project. I've been meaning to crack open and learn about these motors for decades. Once again channeling my inner 8 year old, I took 5 apart and got 4 of them working well again. The fifth one had water intrusion which rusted the electrical innards beyond fixing.

These are Delco branded DC motors. There are probably tons of models, but I've found only left hand or right hand over the years. So rear window motors swap to front if you're in a pinch, but only one side or the other.

To get them out of the car, you'll need to pull the door or quarter panels, and remove the watershielding. Put the window in the all-the-way up position to relax its spring and give you room to work. Look out for that spring, it has hurt people. Disconnect the electrical connector at the rear of the motor and loosen the 3 bolts (sometimes one is hidden too!) from the bottom of the regulator. So you pull the motor and have it on the bench.

Before I start with the disassembly gore, this is a good time to review some tools that help:

Dremel, socket, BFH and grease. Typical restoration tools.

GM didn't seem to want anyone to service these motors. They are extremely well sealed. Dremel wire wheel on the left allows you grind off the goop and get at the screws to open the motor.

Here's a shot of a left hand motor:

Typical GM power window motor from the mid-60's. It has electrical and mechanical halves

What I wanted to see was if cleaning & greasing would speed them up. It did. See below for process steps.

Chris

 

The first problem is getting the motor open. These windows live in a wet, weather-exposed environment in your doors and quaters, so Delco sealed them up very well.

So well that 60 years later it's a pain to open them. There is a set screw at the front of the motor and 3 1/4" hex head screws at the rear. Remove these and the 2 halves come apart.

Wire wheel only the flat side of the hex head. Don't round it off.

I took a sec to polish up the weather-exposed wiring connectors. These high amperage connections live in a tough sometimes wet setting. Every 60 years, why not take a moment to remove corrosion and encourage voltage with clean connectors.

Clean high amperage terminals encourage high speed window operation

Next step for me was removing the front set screw. I'm not sure if this is necessary, but I did it anyway. Here's the set screw I'm talking about. Note the depth of the setting for correct reassembly.

Remove this if you like. If the motor comes apart without removing it, maybe leave it be as it has been for 60 years.

Assuming you've cleaned the sealant goop off the 3 long rear screws, you should see something like this:

A 1/4" deep socket and hammer tap to seat it helps remove the screws without rounding them off. They're tourqued pretty tight from Delco.

So now you can separate the electrical half from the mechanical half. The idea is to clean both and grease up any mechanical spinning mating surfaces for smooth operation. With the screws out, the two halves may need a little tiny screwdriver to pry through the sealant goop.


The electrical half will need cautious polishing. The mechanical half just needs cleaning & greasing.

Good stopping point. We'll get into the electrical motor servicing next. Hope you guys are enjoying this.

Cheers
Chris

 

The basic job here is cleaning the collar of the commutator (a.k.a. the spinny thing) and the contoured surfaces of the motor brushes. I did that with my dremel with a wire wheel. The job is really just polishing the dust and grime off. I aimed at a shiny finish on the commentator collar and just lightly cleaned the edges of the brushes.

Looking down at the top of the electric motor, you'll get this view:

This photo is missing the springs that hold the brushes fast to the commutator, but this is what you'll see when you slip the mechanical half away from the electric motor.

To get the commutator out for cleaning & polishing you'll need to take the brush springs out (and store them safely....). Once the brushes are den-tensioned, you can slip the brush holder up by pulling on the side clips which hold it in place. When the brush housing is up a half inch or so, you can gently slip the brushes out of their brass housing. Be gentle, don't break the brush wires...

When the brushes are out of their housings and loose, you can slip the brush housing up over the end of the commutator using a high angle:

Slip the brush housing over the front end of the commutator. Then you can lift the spinny thing out for polishing & greasing.

I polished the ends of the commutator and regreased them with dielectric grease. Only do the front end after reassembly of mechanical and electrical halves or you'll get grease all over the brushes...

A polished & greased commutator is a happy spinny thing.

Up close and personal on polishing the commutator brush collar:


I went for a shiny finish figuring that would be best conductivity / max voltage. With dremel it takes just a few minutes. But those d*mn wires fly off here & there and become splinters for _Months_ afterwards...


There's a gotcha on the end of the commutator. There are 2 bearings/washers that can get lost. Here's what they look like. Just be sure you remove them from the mechanical side on disassembly and keep safe. Then stick 'em on the end of the commutator with a little grease to hold 'em in place as you slip the electrical side back into the mechanical side. This is what to keep track of:

Don't lose the two washers on the nose of the commutator. They often get stuck in the mechanical side of the motor beneath the set screw.

Hope you're having fun. I did. Next up let's get to cleaning the brushes.

Cheers
Chris

 

The brushes are carbon and wear down over the years spreading dust inside the motor and onto the collar of the commutator since they're spring loaded to ride against it. My goal here was to clean the contoured (and all other) edges of the positive and negative brushes to restore the mating surface to something like what it was 60 years back. Here again I was very gentle with my dremel wire wheel. The goal is clean without recontouring the mating surfaces. A couple of shots may help:

Clean the contoured surface of the positive brush. While you're at it sand the circuit breaker points clean too. Decades of arcing can leave a pitted mating surface.

Well, what good is 1 cleaned brush? Here's the negative side. Gently clean the contoured surface like you did the other side:

Clean the rounded contoured edge first. I did the other edges too just for good measure.

Once the commutator collar and both brushes are clean, you're most of the way through. Let's get to reassembly next.

Cheers
Chris

 

I started reassembly by slipping the positive brush back into it's housing like this:

The brush housing has two slots. The wire slips into one. The retention spring slips into the other from the outer edge.

To get the commutator back in, leave the negative brush out. Then use the high angle trick to raise the brush holder up and slip the commutator back in. It looks pretty much like this:

Angle the brush holder up, slip the spinny thing back in. Rotate the output shaft to confirm the commutator is seated and rotates fairly freely.

With the commutator back in, raise the brush holder just a little to allow you to put the negative brush back in its brass housing on the holder. It's a little fiddly to be sure. The contoured edge should have something very close to the curve of the commutator collar. You may have to raise & lower the brush holder to slip the brush back in. Take your time. It fit that way for 60 years. It should go back in again with a little patience.

Once the brushes are in, it's time to put the tension springs back on. These springs hold the brushes against the spinning commutator collar. Here's what I did:

Tension springs hold the brushes against the commutator. I used a small screwdriver - bottom of spring slides against the rear of the brush, top of the spring is hooked under the tab on the brass housing.

On the mechanical side, more or less all I did was clean out old dried grease and load it up with Sil-Glide. I'm not sure if that's the best grease, but it's what I had around. Again look out for those two bearings on the nose of the commutator.

Not to make light of reassembly, but from here just slip the electrical half back into the mechanical half and screw them back together.

Takes about a half hour or so per motor. Fun little project.

Hope that helps
Chris

 

Final thing is you may want to apply some new kind of sealant. I haven't yet, but will probably use silicone since rain and car washes will be part of this electrical motor's future.

Chris

 

Excellent write up!
I've done a few tune ups, just cleaning the dried grease out of the tracks and replacing with fresh Lubriplate. Never rebuilt any motors, though.

 

That's the good stuff right there! Great write up Chris as always. I repaired mine last year and went through a similar process but it's really nice to see it presented so elegantly.

 

Great write up!
Thanks, this is on my list to do when I redo my door panels.