Unusual Power Window Motor Failure

Mike8675309

Registered User
Last fall my drivers side window motor failed in somewhat typical fasion. Where the motor is still running but the glass isn't. So I took a couple hours and was going to replace the motor pegs with some from an old motor I had. So I pull the motor out, open up the gear assembly and look. The pegs are all there. I grab the gear and try to turn it with my hand and it dosn't budge. I turn the key on and plug the motor in and press the button and the motor moves. WTH?

So I put the motor back together and into the door and now it rolls up my window.? So I button up the door and pull the car out of the garage. Two days later I go to roll the window down and it doesn't come down and the motor sounds like it is running. With no time before winter I just figure I won't use the window.

Last weekend I finally had some time to take a look at what was going on. So I pulled the door panel off and pulled the motor out thinking maybe the gear in the door stripped? Pulled the motor out and tested, key on the gear still turns when running it. But hmmm, that gear looks like some galling on it. So I put a vice grip on the gear and run the motor and what do I know, that gear is really two pieces and one of them is spinning on the shaft.

Now this was a new window motor, but I can't remember where I got it from. I think NAPA. In the past I had received Dorman motors from RockAuto. Luckily I still had an old tired motor that had a good gear and I canabalized the gear from the motor. This gear didn't appear to be 2 pieces.

So the point of this post is a word of warning, some of these window motors may have two piece gears and may not work in place but look like they work when testing. Note this motor had an snap ring retaining the gear to the shaft. The dorman unit I had used an e-clip.

Here is what the assembled gear looks like. Note the signs of galling on the surface under the gear teeth.
IMG_20140705_173906 by mike8675309, on Flickr

Here you can see that this is really two pieces.
Power window motor gear by mike8675309, on Flickr

And here is the problem. They essentially used a round facing on the gear teeth and the coupling below is a hexagonal opening.
Power window gear assembly by mike8675309, on Flickr

It looks like all that they did was press the two parts together during assembly. Eventually the clearance opened up during use and allowed the toothed gear to spin on the shaft.
Power window Gear detail by mike8675309, on Flickr
IMG_20140705_174056 by mike8675309, on Flickr
 
Hmm...is strange, but are you sure the rounded face on the 1/2 gear didn't start life as a hex?
 
Hmm...is strange, but are you sure the rounded face on the 1/2 gear didn't start life as a hex?

yep, it was round. There are marks showing it pressed into position that made it slightly round with flat spots. My only guess is a manufacturing defect where the part was supposed to start round, and get ground to fit but was manufactured undersize so grinding did nothing and it just got shoved into the other part. The flats you can see on the one picture were forced on there. the flats end close to the gear face in some spalled up metal from being pressed into the shape.

I just wanted to post this so others who find the same behavior (it doesn't work, but pull it out and it works and shows now problem and put it back and it still doesn't work) that they look a little further than just the broken pegs that are the primary failure we have seen.
 
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window drag

Must be some excessive drag , dry window guides like the felt in the door front & back , booster spring in the door. I had the spring round off the flats. Whit motor out flat handed hold both in/outside of glass & pull it up & push it down in the tracks & see if it is smooth & easy or not & find out why. 20140406_154122.jpg
 
Window guides don't really dry out and increase drag. They "wear out" and increase drag. The guides are rubber with felt attached. Over time the felt wears away and you are left with exposed rubber which increases friction. I'm not aware of replacement channels for the Thunderbird. There are some products out there that can replace the felt with a glue on type felt fabric that you can glue into the channel. I've only heard about it from upholstery shops that do convertible tops.

With the motor out I can easily move the glass.
 
Right , something to that effect. I have like problem on my 89 & I have new motors in it. Years ago J.C. Whitney sold bulk window strips & I am sure they can be had from other places , I will check into that. Brother installed in his 76 F-100 & it was heavenly smooth & tight.
 
Right , something to that effect. I have like problem on my 89 & I have new motors in it. Years ago J.C. Whitney sold bulk window strips & I am sure they can be had from other places , I will check into that. Brother installed in his 76 F-100 & it was heavenly smooth & tight.


Check here, note the rolls at the bottom called Mohair Window Channel Liner. Come per foot at just over $3.00 /foot.
http://www.b-dco.com/ecom/shop/category.aspx?catid=7

Tells me that local body shops or like I said places that can do convertibles might have a roll they will sell you a few feet of. I'm going to check into it myself just to see how easy it may be to do. I haven't tried to pull the window channels out, but I have to assume they do come out somehow.
 
I'm going to check into it myself just to see how easy it may be to do. I haven't tried to pull the window channels out, but I have to assume they do come out somehow


Sounds like a local pick-a-part experiment to me, no need to screw your stuff up learning the ins and outs :p

Adam
 
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