Not sure what happened, I posted this response into this thread, and it ended up in another one.

So, copy/pasted it into here:


Alright, I'm fed up. I replaced the motor today and it made no difference. It's still weak and I have to turn the key and pull on the window to get it to go up.
I lubricated all the gears with lithium grease, the channels and new weather stripping with silicone spray, new motor, good wires, etc.
I have no more ideas of what to do.
Any thoughts? I'm fed up with this.

 

Does the motor spin at a good rate plugged in, torquing/moving a bit when it cuts on and off, when not attached to the window mechanism?

 

Yes, it snaps well when I tap the key.

So, I removed the motor this morning, disconnected the regulator from the window, and removed the guides on the side. The window is completely free.
It's STILL difficult to slide up and down. It gets caught on the new weather stripping.
What it looks like is the tailgate and weather stripping are perfectly straight, yet the glass is curved. Not curved top to bottom, but side to side. So, when the tailgate is down and you're looking at the top of the glass, the center bows out further than the sides do, which presses on the weather stripping and makes it bind.
Is it possible for glass to warp over time?

 

No. Not without a very high heat.

 

I've diagnosed the problem down to the window binding with the new weatherstripping. The corners just press against it SO HARD that there's too much friction for it to go up and down. You can hear it in the video. (Which is why I was asking about glass getting curved).

It just seems curved wrong.

Now, a note to point out is that the outer tailgate trim has been missing since I got the Bronco 10 years ago, which is why it never binded like this before. Once both pieces were in place, it won't go up, or even down, on its own. With the regulator and motor disconnected, it was difficult to push it past this point by hand.

I've tried adjusting the tracks on the side and where the regulator connects to the window, but nothing makes any difference. It's just so tight.


A fleeting thought I had was that maybe some previous owner put in tailgate glass from a 78/79 Bronco? Then removed that piece of trim to allow the window to move? I have no idea how similar these two pieces of glass may be.

 

Yuck, that's pretty rough.

I was researching and found that it appears the 80-82 tailgate/glass is not compatible with 78/79 tailgate/glass as you need to change the glass and the tracks, otherwise it's going to be too tight or too loose depending on which configuration you are going with. I feel you could be on to something.

 

Anyone have any more thoughts on this? I'm at my wits end and am getting really frustrated.

I have to push the window down to get it to lower, and it takes about 5 minutes to get it all the way up.
What is the proper way to adjust the window channels?

Are there other things that could be wrong that I should check?

I really could use some help. I'm not getting anywhere.

 

I dont know anything else to suggest. I do know that even when brand new these truck rear windows were not the fastet thing in the world operation wise. If you look at the regulator when it is down all the way the torque required to get it started up has to be at least 20 times more than when it is half way up and changes exponentially as it goes up. Wish I could be of more help.

 

I'm out of ideas too, and am about ready to take it to a shop. I hate paying other people to do work I can do, especially when they'll probably just "guess" at it too. Just really hoping someone comes along with some insight into what the heck is going on.

It's not a matter of being slow. I have to pull up on the window to get it to go up. Then, when my hand can't fit anymore, press on the glass and try to get enough friction to help it upward as I slowly work it up and down with the motor the last few inches since it keeps losing speed and stopping. It's downright ridiculous. And this is with the truck's battery removed from the engine bay and brought to the back and directly wired to the motor!

My '84's back window would zip up and down like nobody's business, and I'm sure it still had all the original motor, weatherstripping, etc.

 

Been following your saga bro, something must be wrong with the glass? About your new weatherstripping, is it NOS or a repop from graveyard? I have done a lot of work on my rear glasses and have NOT had your issues with adjustment.

I have been considering a replacement rear wipe since they are back in stock..I wonder if the fit is correct?

I'd try a replacement glass first assuming your side guides are correct. I am assuming you've greased up the main slide and silicone lubed the side channels.

 

Thanks. I actually ordered new glass. The local place only wanted $60 for it, and that's heated (gonna have to figure out how to wire that in), so I couldn't pass it up.

The runs are repros from BGY. They look to be very well made and nice quality.

I think it'd be one thing if I had previously had both strips in place (albeit worn out) and it worked fine, but one of them has been missing since I've had the vehicle. As such, I have no idea how the fitment was, since it always had extra room to wobble around when it went up.

I'll see how it goes once the new glass is in place. Hopefully it's different. If nothing else, fresh glass and the ability to wire in defrost.

 

Sounds like a good plan. If you DO want to wire in that window, if I get around to I have an straight rear harness with the wire involved that does this. I also have an extra paddle, harness I'm installing that will replace the one with the defrost wiring. If it has a any value to you I,d be glad to share it along with the dash switch assembly. I'm not going to use that function on one of mine.

Hang in there

 

Did you check the safety switch to make sure the contacts were not corroded also.

 

Thanks. I'll keep you posted. Currently, I have no idea what it'll take to put it in. The rear harness that you have, where does it start?

 

Thanks for the idea. I actually removed the safety switch because I was tired of it not registering the tailgate as closed when it was. I figure I'm smart enough to know when I should and shouldn't put my window down.