The topic title has been chosen so that it should also trigger Bert's original post from a search. The expanded pics are also rather large so that you can see the detail.

Chris Harris has a Youtube video in which he uses copious quantities of various lubricants and the power of the lifting motor to free up the sliding mechanism but IMO, that's not a particularly good idea because it could be something a bit more nasty jamming things up. I had two windscreen mechanisms, both of which were jammed and both, as it turned out, had something blocking the sliders that lubricant would not have shifted. The first one ran nice and smoothly after cleaning but the second one would not stay in sync. On top of crap in the sliders, this one also turned out to have one severely damaged drive cable and the other was very close to giving up. So, two new drive cables it was. BMW wanted £140 each for them (WTF!!!) but Motorworks will do good s/h ones for considerably less (£40 each). I got unbelievably lucky and picked up brand new left and right drive cables on ebay on successive days from different sellers for just £30 each.

As this windscreen was destined for an RT, the relays are mounted on the crossbar as per Bert's original post. You can use a pair of micro-relays and a much smaller bracket mounted higher up, but this was just the way I chose to do it.

Haynes, eat your heart out

Disassembly.

1. There are seven pretty obvious crosshead screws holding the mechanism to the windscreen mount. It's also obvious in this picture that the lifting arms are out of sync. Remove the three screws holding the lifting motor and put it to one side. Don't worry about drive positioning - we'll deal with that later.



2. That will free up the crossbar. Put that to one side too.



3. Remove the tension springs. They will come off with just finger and thumb.



4. Remove the guide rods. There's a crosshead screw and a rubber o-ring at each end. One screw will always come out easily, but to release the other you will need to hold the slide rod gently! with a pair of pliers.




5. Rod and o-rings. These are new o-rings - the old ones were pretty manky. Change them if you can.




6. Manually move the slider to expose these two dome head allen screws. Don't remove them just yet.



7. Release the lifting arms. There should be a pivot with a circlip at each end. If you look at the right side there's a bit of a giveaway that this mechanism has been apart before and the pivot/circlips were lost. You may need to wriggle the lifting arms off but be careful: they feel like they are cast ally and so could break if handled too roughly.



8. Check the pivots for the guide rod bush. On the other mechanism both nuts were loose and the bush could move sideways. They should be tight against the lifting arm preventing the guide bush from moving sideways but not from rotating easily. Note here that there are two different nuts: the original lefthand one and the pivot had gone awol, so a PO had replaced the pivot with a bolt with the head cut off and the outer threads filed flat to allow a small spanner to grip it. The OEM pivot (right side) has a Philidas nut and the pivot is held with an allen key.



9. Remove these two screws to free up the sliders and drive cables. The tubes will be full of crap. BMW recommend using a silicon grease for the sliders (thanks for the info, Duck), so I used a silicon spray to clean the guide tubes out.



10. And here's part of my problem. The nipple on the end of the drive cable has gone missing. Closer inspection also showed that, possibly as a result of the cable not sliding properly, some of the driven spiral was so badly worn that the motor sprocket was jumping the cable.



11. Remove the two dome head allen bolts you lined up earlier.



12. That will free up the drive cables to be slid off.



13. Pull the drive cables off. Each slider has a nylon shoe on it that can be easily pushed off with fingernails. This one is pretty dirty. Under the shoe are two rubber buffers - one will be out of sight inside the slider. A screwdriver will lift them off easily as they are shaped to fit. This was the second source of the jamming. Crud had got in between the rubber buffer and the nylon shoe, forcing the shoe outwards and jamming it against the slider rail.




At this point, clean everything thoroughly.

14. These are my replacement drive cables. The one on the left has the nylon shoe removed to show the rubber buffer. Once you have cleaned everything, push the rubber buffers back into place and slip the nylon shoe back on top. Yes, the cables are hairy! I suspect this is to trap lubricant. At this point I found a third problem - something had been dropped on the drive cable side of the l/h slide rail and had driven the drive cable into it. I used a very fine file and 600 grade wet'n'dry to remove the dents and realign the edge.



Reassembly follows!

Reassembly.

The really, really good news is that most components are marked (L)eft and (R)ight.

15. Put a thin layer of silicon grease into the slide rails. Push the drive cables back onto the slide rail and refit the two domeheads. Note that there is a slight flare at one end of the slide rail (sorry - no pic) - this is the end that the cable should emerge from. Test for free movement. It will feel stupidly stiff but as you work it, it should start to free up. You'll need to use judgement on this. It's never going to slide really freely because the tolerances are very tight.



16. Spray silicon lubricant on the drive cables and thread them back through the tubes. They pass over a spring plate where the motor sprocket engages, so you may need to push the drive cable nipple down to thread into the end tubes. Reattach the tubes to the sliders. Note that the securing brackets are marked L and R but if you try hard enough you can get them on the wrong way round.



17. Reassemble the lifting arms and pivots. Note how the arms are relative to the end of the slide mount. You can get these on upside down without really trying...




18. Refit the guide rods and grease with silicon grease. New o-rings are a good idea if you have them. Again, to get the second screw in, you may need to gently grip the rod with pliers. If you do, check for indentations and use fine wet'n'dry to sand them out if necessary (very unlikely. I've done four rods with no problems).



19. Replace the springs and that's the mechanical side done. At this point it's a good bet that the arms are not in sync, so carefully push the lifting arms into the fully down position i.e. towards the bottom of the guide rods.




And on to the drive motor!

[Edited for over-enthusiastic use of some keys]

Drive motor

This is really two things rolled into one. If you're not having problems with the limiting micro-switches (IME the inside side plate pops off and exposes the switch parts) and don't need to replace them, but do need to resync the motor to the lifting arms, go down to section 5.

1. These are ordinary commercial micro-switches of the size that are often used for brake switches and you need two. They measure 20 x 10 x 6mm. As 12mm is slightly thicker than the original double switch (11mm), I used a fine file to smooth off the molding on both sides of one switch and the inside face of the other. As it turned out, I don't think it was necessary.



2. Using a countersink bit, drill out the rivets from the back of the housing to release the micro-switches. This is, of course, the inside...



3. Mount the new switches using 15 x 2mm screws. They will fit through the original rivet holes and line the new switches up perfectly. Use nutlock/threadlock high strength on the nuts and don't tighten them hard. When they butt up against the switches, one-eighth of a turn further will do. Any tighter and you stand the chance of locking up the switch internals.



4. You can just see the nutlock spreading out under the nuts.




5. To resync the motor to the lifting mechanism, you need to dismount the motor from the gears. Remove the two screws holding the motor to the gear box (left arrow - one on either side of the motor) and slide the motor out. Rescue the two captive nuts from the windings... On the blue gear there is a single tooth that is much larger than all the others in that ring (right arrow).



6. With apologies for the slightly out of focus picture, rotate the metal gear between finger and thumb until that large tooth lines up with the leading edge of the metal tooth's mounting bracket (marked in green). It willl go loose-tight-loose-tight as you do it because there is a cam in there. As you line the two up, the gears should be in a loose phase.



7. Slide the motor back in. It won't disturb the gears as the worm drive takes up. Setting the captive nuts in the right place can be a nuisance. I did it by standing the assembly on the gearbox so that the motor is pointing at the bench, then carefully sliding a captive nut into place. I then (very gently!) slid a small screwdriver on top of the captive nut to put pressure on it, thus holding it in place while I put the motor back on the bench and engaged the mounting screw. The screws have bevelled noses to make engagement with the captive nuts a lot easier. The large blue tooth is slightly easier to see in this pic so I've re-marked it.



8. Done. The gearbox is now synched to the fully-down position (again, thanks Duck). This time you can see the large tooth pointing to the edge of the bracket. Double-check that the lifting arms are still in the fully-down position and screw the drive motor back on with its three screws.



That's all folks!

https://www.youtube.com/watch?v=fWkdCsruXV0

One thing I noticed from the original thread is that although there are wiring diagrams, none tell you which relay pin goes to where. Robmack commented that you don't need two fuses as per the original diagram, so I only used one. I used red-black for the power feed because, why not? (Actually, because BMW don't use it). Also, the original K1100 diagram keeps changing wiring colours as it goes through the loom, which IMNSVHO, is a damn stupid idea because it makes fault-finding more difficult. So, here's mine sticking as closely to the original colours as possible. Please note that the UPPER limiting switch (yellow-violet) is the microswitch that is next to the mounting plate (inside microswitch, if you like).

I recall reading a long time ago that the windshield mechanism is the same as BMW used for the sunroofs in the automobiles and that you could get parts at junk yards.

Any truth to that?

I think it was Rick that said the BMW M3 side windows motor was the same. The motor is not a BMW-branded part (don't ask - I threw the labels away after I peeled them off the expose the captive nuts) so yes, it's a good bet that it's a common part.

The motor itself is a very common one for BMW (electric seat adjustment, sunroof and side windows) however on some the shaft can vary depending on what the application is. I remember Inge saying the sunroof motor on his 5 series was the same. Some of the motors have a worm drive spiral on the shaft and others have a much shorter shaft with a gear keyed onto it.

I think it's a 54131378645 for 1985-1995 E32 and E34 series sunroofs. The motors were made by the German company Webasto.

It looks like Google agrees with you. I'm finding them NOS in the UK for just £32.

[Edit] It appears that's a one-off aberation. Most s/h ones are approx £45 upwards.

I have had to deal many times with stuck electric winshields.

Once, I even had to heat the tubes to free the cables: then all the "hair" garnment that is hold inbetween the spirals burnt and the cables were loose.
I think that it this feature that keep moisture and dirt into the tubes (instead of avoidint it to enter) and permits corrosion.
Since then, I have applied this method to all the electric winshilds I had: a close shave, a bit of silicon lubricant and it's Ok for years (decades?).

 Now that is what I call "a job well done"...
Fábulous Dai, well documented and foolproof! Thank you so much for your trouble!
Jos

duck wrote:I think it's a 54131378645 for 1985-1995 E32 and E34 series sunroofs. The motors were made by the German company Webasto.

I believe this is correct. It was never a motorbike only motor, the bean counters would never have allowed it. Same as the fuel pump is in millions of cars around Europe....or Brembo brakes also found on Moto Guzzi,.....

Dai wrote:One thing I noticed from the original thread is that although there are wiring diagrams, none tell you which relay pin goes to where. Robmack commented that you don't need two fuses as per the original diagram, so I only used one. I used red-black for the power feed because, why not? (Actually, because BMW don't use it). Also, the original K1100 diagram keeps changing wiring colours as it goes through the loom, which IMNSVHO, is a damn stupid idea because it makes fault-finding more difficult. So, here's mine sticking as closely to the original colours as possible. Please note that the UPPER limiting switch (yellow-violet) is the microswitch that is next to the mounting plate (inside microswitch, if you like).

Have you wired the power for the motor through the micro switches?
Or am I reading the diagram wrong?
Is that the original way to do it?
I would let them cut the coil circuit at the limits. You could argue that the relay switches could weld together and you need a mechanical switch to break the circuit.

That's also the way that's described in this post: https://www.k100-forum.com/t50-mounting-an-electric-windshiel-on-a-k100rt#8094 by user  @robmack

The diagram is the OEM method; no changes or updates on my part. The diagram is electrically the same as Robmack's but with the relay pin numbers added. Also, the microswitches are rated 3Amps @250Volts =  750Watts which is more than enough for the 4Amps @12Volts = 48Watts that the windscreen motor is drawing.

No, it's not the same as  @robmack 

In his verbose description, he clearly states that he uses the micro switches to cut the circuit to the relay coils.

Both the amp and volt rating of a (micro) switch is important, both have to be within range. I wouldn't put it past automotive manufacturers to use a size too small, though.

You're right; after doublechecking I found mine was scanned from the Clymer manual, so my apologies to Robmack for blackening his good name . However, what I said above regarding the microswitches still stands - they are more than good enough to take the power required by the windscreen motor. In my opinion (and this really is just my opinion and is not aimed at anyone else), given the rating of the microswitches I think that rewiring them to cut the relay coil feed is a solution in search of a problem.