Seat Lock Mystery (Pics)

[ddebonis]

Hello,

When I bought my bike, the previous owner said the seat lock didn't work -- it would just "spin in circles." Then he handed me a bag of parts...

As I try to fix the seat lock, it appears I have two problems.

1) Do I have all the pieces for the seat lock?
2) Why is the key hole piece spinning and how do I stop it?

Please see pictures below and let me know if I am missing any pieces (and if I can easily buy replacements or fabricate new ones). I think I am missing a part that keep the latch extended/the push button popped out. The latch and button don't stay in place except when seat is closed and locked.

[IMG width="450" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0681.jpg[/IMG][IMG width="450" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0685.jpg[/IMG]
[IMG width="450" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0689.jpg[/IMG][IMG width="450" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0684.jpg[/IMG]
[IMG width="450" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0686.jpg[/IMG][IMG width="450" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0687.jpg[/IMG]

For the spinning issue, it appears the key hole is supposed to be fastened to the frame, but it's come loose. I am guessing this small phillips head screw gets tightened into the frame to secure it. The screw also looks a bit stripped already. There is also a point when it turns that it appears to sit flush against the metal plate. Do I have this right? If so, how do I access this screw?

[IMG width="800" height="500"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0691.jpg[/IMG]
[IMG width="800" height="500"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0682.jpg[/IMG]

Thanks for any help!

[bruce_launceston]

You appear to have all the necessary pieces. It is easy to drop the black mudguard to improve access. There are bolts in the tailpiece storage box and 2 at the top of the subframe, the front of the guard hooks over some lugs.
Find a new screw with good thread and slots and see if it will tighten.

[montmil]

Moto, your investigation is correct. And Bruce has shared with you the Royal PITA that it is in accessing that tiny screw.

Learned this when I had to replace the entire lock box on my '81 when first purchased.

[Bob_Roller]

Try an oversize screw in the original hole .

Best to do this with the lock off of the bike to get the threads right the first time, not much metal left after getting stripped the first time .  

A 90 degree Phillips screwdriver makes the job a lot easier getting the back plate off .

[ddebonis]

Thanks everybody.

I'll remove the mud guard and see if the screw is salvageable or if I need a replacement.

In regard to my first issue of missing pieces -- it's good to know ppl think I am not missing anything. I am still unsure how tension is applied to the spring which keeps the latch closed. As I said, now it flops around, even when installed. The end of the spring (see green circle below) needs to be pressed up against something. Is there a protrusion on the inside of the frame that this end meets? What holds the spring in place?

-Danny

[IMG width=800 height="600"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0687b.jpg[/IMG]

[Bob_Roller]

I may be wrong about this, but I think the back plate pushes on the spring to give it tension .

Been a long time since I've had one out .

[montmil]

Your last photo, the Green Circle, shows the release button. The button will protrude through a frame-attached face plate. If memory serves, there is a "stop" for the spring that becomes fairly understandable when the entire assembly goes back onto the bike's chassis.

I just went out to look at my R65s and, d'oh, you can't see nuttin' when the lock assembly is all buttoned up. Try a quick assembly and eye ball what you have. It's all there. Think Rubic's Cube.

[Red_Hen]

I have to laugh - I went through the same process.

In the end I decided I didn't need to lock my seat!  

What a PITA design!  In this instance, makes German Engineering an Oxymoron

[Ron_S.]

Well, I guess I'll move "fix seat lock" way farther down the list.  

[ddebonis]

I have to laugh - I went through the same process.

Your laughter only strengthens my resolve!!!  

I may be wrong about this, but I think the back plate pushes on the spring to give it tension .
 

See image, the back plate it flat and doesn't seem to affect internal mechanism at all.
[IMG width="400" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0695.jpg[/IMG]

If memory serves, there is a "stop" for the spring that becomes fairly understandable when the entire assembly goes back onto the bike's chassis.

I've assembled the pieces on the bike and still find that there is no pressure on the spring -- the push button and latch continue to flop around when the lock is open.
 See what the end of my spring looks like (via green arrow):
[IMG width="400" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0693-1.jpg[/IMG]
[IMG width="400" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0696.jpg[/IMG]
[IMG width="400" height="300"]http://i1253.photobucket.com/albums/hh587/ddebonis/IMG_0699.jpg[/IMG]

Perhaps it's bent out of shape, but I it needs to be secured somehow so the spring doesn't spin around. I'm considering soldering it...

I'm also considering soldering the key hole in place...

It is easy to drop the black mudguard to improve access.

I found the bolts you mentioned, but they just spin when I try to loosen and I can't get my hand in underneath with a wrench to keep the bolt in place. Ideas on how to do this? Or I can just get some specialty tools to access the PITA screw on the key hole.

-Danny

[ddebonis]

So I've been playing with extra springs for other ways to put pressure on the latch. I just realized if I spin the spring 180 degrees and have it lean against the short arm of the latch, THEN it's opposite end would resist movement once the back plate was attached.

IS THIS HOW IT'S SUPPOSED TO WORK??? It does seem to offer too much pressure on the spring. I don't want to tip the bike over trying to depress the push button.

[Bob_Roller]

I think that's the way it works, when you put the back plate on, it pushes on the spring and tensions the lock arm .

There should be a small chafe mark on the back plate, where the spring contacts it .

[montmil]

I think the long arm of the spring is bent out of shape.

Here's how I resolved my seat lock issue on the '81 R65:   Your last posted photo -curved long arm on the spring- is perfect. So...

I emailed a few pics of my messed up lock box to RePsycle BMW -an excellent source for used Airhead parts. They responded quickly with what I needed and didn't need. Great folks and very helpful. They are now a primary source for some of the unobtanium parts on our Airheads.

Email that bent spring photo to RePsycle BMW. Ask them what's wanky about your spring.

http://re-psycle.com/

Suggest you call them first on their 800 and alert them to your incoming photo. Perhaps consider purchasing that piece from them... used, of course.

Worked well for me and mine. [smiley=thumbup.gif]

[Red_Hen]

It's a poor design!

[ddebonis]

Update: I fixed the sucker. Took the seat and rear mud guard off. Turns out the screw that holds the key hole assembly to the front plate was not original -- it's head was too big and so could not be screwed in all the way. I had no file so grinding it against concrete sidewalk solved the problem. I was then able to tighten it all the way. I figured out the spring mechanism too.

BOOYA!!!!

If anyone needs help with their seat lock, just let me know.

-Danny