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I've read the factory service manual. But got nothing.
My friend has a 81 with power windows. I don't have power windows in my Vette so I have no experience here.
Let me explain the issue. Window will go up. But stops short of the stops in the vertical channels. So he has a 1/4 inch gap at the top. Letting in wind and rain. Normal adjustment would be to move the stops up in the channels. But the rollers don't reach the stops. On the way down the rollers hit the bottom stops with glass properly aligned with top of the door, BUT the motor wants to keep going and actually bulges the inner panel of the door outward , as in bulging towards the inside of the car. Taking one's finger off the switch just as the window hits bottom of course eliminates that issue. But it's not right.
So, glass doesn't go up enough, regardless of the stops. And wants to go way to low.
What do I look for here?
I think the system is supposed to switch off at end of travel by a surge in current tripping the 30amp circuit breaker in the fuse box. Sounds like that is not happening on the down stroke, so maybe the circuit breaker isn't working or perhaps there is resistance in the circuit preventing the current from ever getting large enough.
Well, thanks for that. But that really is the least of his worries. He really wants the window to close all the way.
I just wanted to explain all the symptoms. Something isn't aligned or meshed correctly is my guess. But would love to know what to look for.
Factory service manual shows nothing. Factory unit repair manual shows nothing on power windows.
Not sure how similar '72 is with '81, so maybe this isn't doable...
The motor can be removed from the regulator without anything happening to the assist spring - the weight of the window and all keeps it from unwinding. Without the motor, can you manually raise the window to the top stops? If not, it's the tracks and wheels binding and not a motor issue.
My motors don't have any sort of at-the-motor switch to stop them on the up or down - you just let go of the console switch when the window stops. Bulging out kinda sounds like broken welds. Is there a loud banging sound when the door is swung closed? This indicates broken welds between the motor mount and regulator, maybe causing some sort of misalignment.
Last edited by barkingrats; Jun 19, 2026 at 10:16 AM.
No bangs or rattles that I noticed. But I don't drive it. I know I'm going to have to pull this all apart again. Was hoping for something to look out for. I had the glass out completely to remount his mirror. Nothing looks out of the ordinary with the channels. Rollers are a bit worn but not super bad. I am able to adjust the glass in every way. But can't get it to go all the way up. Really strange.
I remember going through this many years ago whenever bringing the window down it would run beyond the stops and buckle the door a bit and not remembering the fix, would appear the regulator itself is set too low so the range is also too low, is there adjustment in the regulator location to the door shell?
Last edited by Golfobsessed; Jun 19, 2026 at 07:56 PM.
Maybe the motor is not clocked properly in the regulator? It sounds like the up travel is too short and the bottom travel is too long. If he has had the motor out of the regulator maybe the gear was moved somehow before he put the motors back in?
Maybe the motor is not clocked properly in the regulator? It sounds like the up travel is too short and the bottom travel is too long. If he has had the motor out of the regulator maybe the gear was moved somehow before he put the motors back in?
he said the motors were replaced some time ago with new ones. Has had issues since. How do I reset the gears? Are there alignment dots or something?
Found this in my 1969 service manual. I don't think that there were any major changes in that area until the C4 came out. Don't know if this will help, but it is all I could find. I have manual windows.
There is no clocking of the motor to regulator. The motor just spins and spins in either direction until the power is disconnected. What stops the motor when it's in the door is the top and bottom stops in the tracks (or binding). So when you mount the motor to the regulator, whatever up/down position the gear is in will mesh with the motor's teeth - just secure the 3 bolts and off you go.
4-vette, remove the door panel and motor access panel and watch the motor, tracks, and window as you operate the switch. You should be able to see the rollers and vertical tracks as it rises from both below through the access hole and above through the window slot. When the window runs down to the bottom, you should also see what's causing the bulge. (BTW, if the access panel is missing, the motor may be moving against the door panel just from stopped motion torque alone.)
I had it apart a week ago. I watch the rollers go up the vertical tracks. All seems fine. Then the window stops 1/4inch from the stops. And the motor stops running. Adjusting the upper stops does nothing. Nothing in the vertical tracks. Could there be an issue with the horizontal channels? Foreign object blocking something?
I had it apart a week ago. I watch the rollers go up the vertical tracks. All seems fine. Then the window stops 1/4inch from the stops. And the motor stops running. Adjusting the upper stops does nothing. Nothing in the vertical tracks. Could there be an issue with the horizontal channels? Foreign object blocking something?
Well, they do have to slide fore and aft as the scissors move. Have you greased all the rollers, slides, and tracks?
I don’t know if this will help you out, but Wilcox has several write ups and instructions covering window mechanisms and adjustments.
I don’t have any of their instruction sheets but there has been many forum members who swear about how helpful they have been in adjusting and trouble shooting windows.
Yes everything moves smoothly. Yes I completely understand how to adjust the glass. I can adjust it perfectly.
except it won't even reach the upper stops in the vertical channels . Hummm. Back apart when I find the time. But the only thing I could think of last time is the gears are not synced right. Nothing stood out.
Correct there is no adjustment in the motors, but the gear must be centered before you bolt on the motors. Here is a pic of the regulator from my 78 before I put the motor on it. Note the label that says do not remove the bolt before the motor is attached. Maybe someone along the way didn't pay attention and removed the bolt, the gear moved out of center, then put the motor in. Maybe. line up the hole, put a bolt in it, remove then reinstall the motor. I am not sure how the motor senses it needs to reverse but it is reversing before the end of the gear travel when going up.
Correct there is no adjustment in the motors, but the gear must be centered before you bolt on the motors.
Why?
I am not sure how the motor senses it needs to reverse but it is reversing before the end of the gear travel when going up.
The only "sensing" the motor gets to reverse is when you press the rocker in the opposite direction.
If everything is lubed and sliding, I guess the last thing to check would be the end gear teeth on the regulator to ensure they aren't damaged. I suppose if the teeth were bent severely enough the regulator wouldn't have full travel from the motor.
Last edited by barkingrats; Jun 20, 2026 at 11:03 AM.
I meant to say how the motor senses when to stop. And I have not idea why they would put that warning on the regulator but there must be a reason. If the gear is not centered in the length of travel, that might cause the regulator to hit the end teeth before it is all the way up or down. In my old head, if it doesn't go all the way up ( and we are talking about windows now!) and then going the other way it still wants to move so much it causes a bulge in the door because of the pressure. it must be the gear position.
The warning is there because if you remove that bolt before attaching the motor, the spring will very rapidly move the regulator arm and possibly injure you. As Barkingrats says, it is just a motor that will keep spinning until you let go of the switch or something physically prevents the regulator moving.
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Power window help.
