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Discussion Starter #1
One of the back window switches on my 1974 Shadow I (SRC18947) got stuck in the "up" position for some time before I noticed the motor was running. Now the window will go down, but won't go up unless I pull it up by hand. The motor still runs in both up and down switch positions. My guess is that something must have stripped/broken in the mechanism due to the motor being run for too long with the window fully up. The window was working fine before the switch got stuck.

Any thoughts on what I should look at first? Perhaps the cog or whatever drives the chain at the motor is stripped or loose? I'm thinking that the weight of the glass allows it to go down, but there isn't enough torque to push it back up. I can't see what's going on without removing the whole motor as it is on the backside. What is the cog made of and how does it attach to the motor?
 

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It is very possible the brake solenoid for the window is now shot. It "locks" the drive with a rubber fingered disc that fits into a corresponding plate with holes. It releases when the window is in operation and activated at rest, therefore preventing the window from moving up or down primarily due to the weight of the window in the up position.
This brake is on the opposite side of the center box with the gear inside. You can disconnect the 2 wires going to the solenoid and removing the 2 small BA nuts. You will see the brake setup. The window will operate fine without them in place since they will drag if not working.
 

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Discussion Starter #3
It is very possible the brake solenoid for the window is now shot. It "locks" the drive with a rubber fingered disc that fits into a corresponding plate with holes. It releases when the window is in operation and activated at rest, therefore preventing the window from moving up or down primarily due to the weight of the window in the up position.
This brake is on the opposite side of the center box with the gear inside. You can disconnect the 2 wires going to the solenoid and removing the 2 small BA nuts. You will see the brake setup. The window will operate fine without them in place since they will drag if not working.

If I push the window manually to the full up position, it will start to lower as the car moves around - apparently due to the weight of the glass. Does that fit what you mean above? I found the applicable section in the manual and am going through the diagrams now. Is the rubber disc setup parts #25 and #26 in the diagram?
 

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28908
07210001.JPG


The end in the foreground in this photo is the brake mechanism as a whole. It pops off if you remove the two bolts that hold it on to the drive body. I could swear I have some photos of one of mine when it was off of the drive body and that shows the "fingers" that project through as part of the mechanism.

I have disconnected window brakes and not had the windows move, while others are in your circumstance. If I find the photos of the brake off of the window motor assembly I'll post them.

Over time there's just too much water under the bridge!! Even though I'm pretty darned organized about my photo archive, a few can "go missing" on occasion if I didn't name something intelligently way back when.
 

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Discussion Starter #6
Thanks for the photos. I just removed the solenoid from the drive gear body. I can see the female metal plate with the holes in it, but no corresponding male piece that fits into it. Maybe someone had already removed it? Here is the connection end of the solenoid and the plates/washers that came off.
28909


And here is what's left on the gear assembly.

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Discussion Starter #7
The chain moves when the window switch is pushed down, but doesn't move when it's pushed up. Does this mean my gears are likely stripped? Is removing the motor for rebuild the next step, or is there something else I can troubleshoot before taking out the whole assembly.

Also once I take the motor assemble out as per the manual, will the window have to be held up with tape? If so, I don't want to do that until I know I won't be using the car for a while, or have replacement parts on hand.

I took a short video but couldn't figure out how to upload it here.
 

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Hi Palladio

You will need to remove the assembly to sort this problem. Yes, the window glass has to be held up with tape to do so. However, you could cut a piece of wood to length and use it to hold the window up, once the lift mechanism has been removed, so you can use the car while you are correcting the problem. Another idea would be to use two hose clips around the window guides to hold the window up.

I've included some pics - the last one shows the gearwheel/cogwheel assembly. The gear wheel is made of nylon and may have badly worn teeth. Another possibility is the gearwheel or cog is slipping on the spindle.

Once you have the unit on the bench it should be easy to diagnose.

BTW - the pics do not include the solenoid brake - I removed mine years ago.
 

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Here is the part that is often removed from the window brake.
RRwindow brake disc.JPG
 

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Discussion Starter #10
Very helpful pictures from all thanks. Do I have to remove the chain guides etc. or can I start by just removing the gear drive housing or whatever you call the section with the worm gear and sprocket that sits between the motor and solenoid? Looks like just two bolts holding it on maybe. Any advice on how best to remove it? I've got the service manual but if there are any tricks for doing I right I'd love to know.
 

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Discussion Starter #11
My gut feeling is that a cog is slipping on the spindle. I'd think that if worn plastic teeth were the main issue I'd see or hear some evidence of the gear skipping or chattering no?
 

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Discussion Starter #12
And in this photo previously posted by guyslp, is that a rubber isolation bushing inside the metal chain drive sprocket? If so, could that have worn and cause the sprocket to lose its grip on the spindle?
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Hi Palladio

Many detail changes were made over the years so your window lift on SRC18947 is likely to be the same as mine SRX18501, which differs from the above picture. However, it is quite possible that your problem is due to the gearwheel or sprocket slipping on the spindle.

As I recall, you will have to strip the whole mechanism down to get to the sprocket. It's a straightforward exercise but even so, don't forget to take lots of pics to aid re-assembly.
 

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I do not believe there is a rubber bushing present. They eventually added one later, at least on the SZ cars, and I have a set of instructions on how to fix those when they fail.

My gut tells me that there will end up being an issue with the actual plastic drive gear inside.

The pictures from @Wraithman show the "finger plate" that's a part of the brake mechanism resposible for supplying the push. I cannot imagine why anyone would remove it (which doesn't mean that they haven't, mind you) as simply disconnecting the brake solenoid achieves the same end, if memory serves. It's been a while. I know I never removed any parts from the setup to disable mine, just electrical connections.
 

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When the window receives juice it also activates the window brake to "release" thereby making the window easier to move.
When the window is at rest, the brake solenoid actually "engages" to lock it in position.
So if one were to unplug the solenoid connectors, it will remain engaged, thus creating a drag.
 

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That's how the brake solenoid works on my car (SRX18501). When you think about it, if you needed power to engage the brake, it would have to be on the whole time, other than when the windows were moved up or down.
 

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Like I said, it's been a while . . . I

I have found a slew of other photos, some mine, and some from others who've done Window Motor Repairs. This one involves a plastic gear (and is not mine):

Gear_New&Old.jpg


and although I used tape to keep my windows up when I needed to, that was because I knew I was going to be very slow about getting the project done. This gentleman got very creative with a toilet plunger for a one-afternoon job:

Plunger_Window_Prop.jpg
 
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