I removed my motor and assembly on my 88 (flat sided motor) and it seems to function perfectly except when it reaches one end of the assembly it gets stuck. I can take the motor off and it works perfect and it will travel to the other end and back off perfectly fine but when it reaches the other end ( i think is the window all the way up) it gets stuck.

There isn't any apparently wear in the gears on the assembly or motor.

Any ideas guys?

 

Hi,

I once disassembled the rear window motor of an XJS convertible, and I found there was a stopper rubber inside the gearbox and it was totally ruined.
When the rubber goes bad the gear bites into it and gets stuck.
I removed the rubber as much as possible, then it started moving.

Your case might not be the same with mine but I hope this helps.

 

I don't think so because the motor will run endlessly when taken off the assembly. I also took it apart to clean the contacts and there are no obstructions within the motor itself.

Thanks though!

 

Hi,
2 things spring to mind.
I would look at the mechanism to make sure it is free all the way up and down.
Then try a little silicon grease in the window runners as it may be catching.

Just a thought and hope it helps.

 

Okay so I got it stuck again and couldn't find anything that looked wrong from the outside. So while stuck, I removed the panel and found the problem.

Inside, the electric motor drives a worm gear that runs against a plastic ring gear which drives the outside gear that moves the assembly up and down.

When I removed the cover these gears were on top other and binding, so even with the motor off of the assembly it was stuck.

So when the motor reaches the top of the assemblies gear it keeping torquing and pops out of place. I am assuming this doesn't happen in the reverse direction because of the cut of the gears.

So I guess there is too much end play in my worm gear? Is there any way to change or fix this?

 

There is some type of set screw at the end of the worm gear. Anyone know what it should resemble?
Mine has a flat black bit of material on the end, its either really weak metal or brittle plastic and its chipped up. This obviously affects the end play but I can't see how it does anything in its current state. Should it be cupped or something?

EDIT:
after looking again it seems more like the white plastic ring gear is whats moving and not the worm gear. I don't really see how this goes together but inside the gear is a big ol block of rubber that maybe has too much give now?
dunno what to do with this because all that is pressed together.
Annoyed if i have to get a new motor when the actual motor is fine..

 

If the other side is working correctly, have a look at that one. At least then you will know exactly what you need to repair the defective side.

 

After rifling around a bit I found a picture of a Saab 900 motor rebuild that looks exactly the same and was a bosch.

Looked for bosch motors on ebay and most of them belong to mid 80s mercedes and look identical.

Counted 10 teeth and bought a mercedes motor for 34 dollars. Hope this works..

 

Your teflon gear is ruined. It does not have to have a lot of wear to be jumping worm gear and locking motor shaft. I suggest new Bosch assembly for about $88 online. I found few sources when I got mine few weeks ago.