Window motors (again?)

[pmansson]

Everything in the doors and rear quarter lights is serviced (cleaned, greased, adjusted and more). However, 2 windows need assistance in getting off the end positions. Motors work of course, but only with the aid of a screwdriver will the movement commence.
What is the issue here? Have I set the end positions too far (with the aid of the stoppers)?

 

[pmansson]

Everything in the doors and rear quarter lights is serviced (cleaned, greased, adjusted and more). However, 2 windows need assistance in getting off the end positions. Motors work of course, but only with the aid of a screwdriver will the movement commence.
What is the issue here? Have I set the end positions too far (with the aid of the stoppers)?

 

[Arde]

In addition to motors and rails the other two key items are gearboxes and switches. I replaced two gearboxes with better used ones. The switch resistance is important, you can try to bypass the switch and see if it makes a difference. You can clean the switch contacts or get fresh ones.

Yes, the stop may also be too far out.

 

[Arde]

In addition to motors and rails the other two key items are gearboxes and switches. I replaced two gearboxes with better used ones. The switch resistance is important, you can try to bypass the switch and see if it makes a difference. You can clean the switch contacts or get fresh ones.

Yes, the stop may also be too far out.

 

[pmansson]

Switch contacts: I presume they are OK, as the cogwheel sets off in either direction immediately as the switch is activated/pressed

 

[pmansson]

Switch contacts: I presume they are OK, as the cogwheel sets off in either direction immediately as the switch is activated/pressed

 

[Arde]

Switch contacts: I presume they are OK, as the cogwheel sets off in either direction immediately as the switch is activated/pressed

That only means they make contact but doesn't say what resistance they present.

A DC motor has max torque and max current consumption when it is not moving yet. Any resistance the switch has will detract from the initial torque and will translate into heat at the switch while you press harder and longer hoping the window starts to move. Mine had 6 ohms or so and showed carbon deposits on the inside. You can rule this out by connecting the window motor directly to the battery and see if the window moves.

 

[Arde]

Switch contacts: I presume they are OK, as the cogwheel sets off in either direction immediately as the switch is activated/pressed

That only means they make contact but doesn't say what resistance they present.

A DC motor has max torque and max current consumption when it is not moving yet. Any resistance the switch has will detract from the initial torque and will translate into heat at the switch while you press harder and longer hoping the window starts to move. Mine had 6 ohms or so and showed carbon deposits on the inside. You can rule this out by connecting the window motor directly to the battery and see if the window moves.

 

[jmackro]

I have been reassembling my coupe following painting, and have spent a LOT of time tinkering with the windows.

As Arde says, the switches may work, but even when new, the design of the switches imposed a lot of resistance into the motor circuit. You have a long length of wire, multiple connectors, plus the switch contacts between the battery and window motors - all this adds resistance which results in less current getting to the motor. I ran a 10 ga wire directly from the battery to relays on my doors & rear windows, so that now my console switches are just operating the relay coils. That helped a LOT on my car.

Another thing to look at is whether the windows are binding at any point in their path. The fact that yours go up OK, but stick at the bottom tells me that something is causing resistance (here I'm talking mechanical, not electrical resistance). Did you remove the old grease before applying fresh lubricant? In the case of the front windows, it is possible that the front and rear tracks aren't parallel, causing the window to "wedge" at the bottom. I would recommend removing the motor/gearbox/arm assembly, and working the windows up and down by hand - feeling for places where they may be binding.

 

[jmackro]

I have been reassembling my coupe following painting, and have spent a LOT of time tinkering with the windows.

As Arde says, the switches may work, but even when new, the design of the switches imposed a lot of resistance into the motor circuit. You have a long length of wire, multiple connectors, plus the switch contacts between the battery and window motors - all this adds resistance which results in less current getting to the motor. I ran a 10 ga wire directly from the battery to relays on my doors & rear windows, so that now my console switches are just operating the relay coils. That helped a LOT on my car.

Another thing to look at is whether the windows are binding at any point in their path. The fact that yours go up OK, but stick at the bottom tells me that something is causing resistance (here I'm talking mechanical, not electrical resistance). Did you remove the old grease before applying fresh lubricant? In the case of the front windows, it is possible that the front and rear tracks aren't parallel, causing the window to "wedge" at the bottom. I would recommend removing the motor/gearbox/arm assembly, and working the windows up and down by hand - feeling for places where they may be binding.

 

[pmansson]

Adding to the facts: a few weeks ago they worked fine. If you stop anywhere except in the end/extreme positions, they will immediately get going on their own. The door window sticks in the bottom position and the rear window in the top position.

Any point in changing the actual switches (black&chrome)? I have several new ones. This particular car has the early kind ones without the grooves on the black parts.

 

[pmansson]

Adding to the facts: a few weeks ago they worked fine. If you stop anywhere except in the end/extreme positions, they will immediately get going on their own. The door window sticks in the bottom position and the rear window in the top position.

Any point in changing the actual switches (black&chrome)? I have several new ones. This particular car has the early kind ones without the grooves on the black parts.

 

[jmackro]

The fact that the windows jamb in their extreme positions suggests to me that the problem is mechanical, and not electrical. So I doubt changing the switch will make any difference.

Sure, getting more amperage to the motors might give them enough additional "oomph" to overcome the binding - but changing the switches to ones with lower resistance contacts can't add more than a few milliamps - even if it made a difference, the next cold day the grease would solidify to the point where they would stick again.

I'd still like to hear the results of trying Arde's trick of running a long, heavy-gauge wire from the battery + terminal directly to the motor, and see how much difference that made. If it makes a lot of difference, I would recommend the relay solution - not just new switches.

But again, I'm predicting that freeing up the mechanical binding will be the most successful fix for this.

 

[jmackro]

The fact that the windows jamb in their extreme positions suggests to me that the problem is mechanical, and not electrical. So I doubt changing the switch will make any difference.

Sure, getting more amperage to the motors might give them enough additional "oomph" to overcome the binding - but changing the switches to ones with lower resistance contacts can't add more than a few milliamps - even if it made a difference, the next cold day the grease would solidify to the point where they would stick again.

I'd still like to hear the results of trying Arde's trick of running a long, heavy-gauge wire from the battery + terminal directly to the motor, and see how much difference that made. If it makes a lot of difference, I would recommend the relay solution - not just new switches.

But again, I'm predicting that freeing up the mechanical binding will be the most successful fix for this.

 

[bengal taiga]

More on the subject

The fact that the windows jamb in their extreme positions suggests to me that the problem is mechanical, and not electrical. So I doubt changing the switch will make any difference.

A couple of thoughts.

This subject has been addressed before and looking at this thread might be beneficial: http://e9coupe.com/forum/viewtopic.php?t=354

I have a different take on the switch swap suggestion. I agree if the windows are binding mechanically either because of stuck/worn regulators or due to restricted guides, even a starter motor driven regulator may not cure the problem. However, you have two switches in each circuit - any of which could be gummed up of corroded enough to create mini-shorts. I have had several situations where only the rear armrest switch would function while the shifter switches were at best, erratic.

I found corrosion and baked grease or some other contaminants on all the switches near the shifter. I have also found a broken spring and cracked plastic housings that clearly impaired switch function. I can only speculate whether the placement of the switch just above the transmission (exposing them to years of heat and fumes) caused the problems or if it was just plain hard wear and user exasperation. (If you compare the switches with the round terminal switches found on newer models, it is not difficult to decide which might be the better design.)

Since it is so simple to swap the old switches for new, I see no harm in trying it. But I agree, the chances of this fixing the problem are remote.

Good luck.

 

[bengal taiga]

More on the subject

The fact that the windows jamb in their extreme positions suggests to me that the problem is mechanical, and not electrical. So I doubt changing the switch will make any difference.

A couple of thoughts.

This subject has been addressed before and looking at this thread might be beneficial: http://e9coupe.com/forum/viewtopic.php?t=354

I have a different take on the switch swap suggestion. I agree if the windows are binding mechanically either because of stuck/worn regulators or due to restricted guides, even a starter motor driven regulator may not cure the problem. However, you have two switches in each circuit - any of which could be gummed up of corroded enough to create mini-shorts. I have had several situations where only the rear armrest switch would function while the shifter switches were at best, erratic.

I found corrosion and baked grease or some other contaminants on all the switches near the shifter. I have also found a broken spring and cracked plastic housings that clearly impaired switch function. I can only speculate whether the placement of the switch just above the transmission (exposing them to years of heat and fumes) caused the problems or if it was just plain hard wear and user exasperation. (If you compare the switches with the round terminal switches found on newer models, it is not difficult to decide which might be the better design.)

Since it is so simple to swap the old switches for new, I see no harm in trying it. But I agree, the chances of this fixing the problem are remote.

Good luck.

 

[oldcoupe]

One of my windows, after a rebuild, would go down fully and not return.

The problem was in the switch.

The earlier switches with spade connectors have an unused terminal. Using the circuit diagram in the BMW Blue repair manual I was able to rejig the wires to use the unworn internal contact and it's ok now.

I did the fix a couple of years ago, so don't remember the detail, but once I'd worked it out, it only took a few minutes and saved the cost of a new switch.

 

[oldcoupe]

One of my windows, after a rebuild, would go down fully and not return.

The problem was in the switch.

The earlier switches with spade connectors have an unused terminal. Using the circuit diagram in the BMW Blue repair manual I was able to rejig the wires to use the unworn internal contact and it's ok now.

I did the fix a couple of years ago, so don't remember the detail, but once I'd worked it out, it only took a few minutes and saved the cost of a new switch.

 

[Arde]

The earlier switches with spade connectors have an unused terminal.

Precisely, one neat trick one can pull once is to "rotate" the switches. That is, unplug the wires, rotate the switch 180 degrees and plug again the wires to the previously unused contacts (mirror image laterally). The switches are symmetrical so they will work just fine, and after rotation you would be using two new contacts that were not carrying any current before.

 

[Arde]

The earlier switches with spade connectors have an unused terminal.

Precisely, one neat trick one can pull once is to "rotate" the switches. That is, unplug the wires, rotate the switch 180 degrees and plug again the wires to the previously unused contacts (mirror image laterally). The switches are symmetrical so they will work just fine, and after rotation you would be using two new contacts that were not carrying any current before.