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Thread: Stock '81 R100RT seat not latching properly

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    Question Stock '81 R100RT seat not latching properly

    I've been having problems with my seat, but haven't been able to find any solutions yet. The closest I came to someone having my problem was this thread, which was with an aftermarket seat: http://www.bmwmoa.org/forum/showthre...seat-on-R100RT

    I'm the second owner of the bike, and the original owner had an aftermarket seat on it for many years, but kept the original. I want to try using the original, since I like the way it looks more, and it seems like it wouldn't be terribly uncomfortable (time will tell).

    Here's the situation, though. When I fit in the swing hinges properly and close the seat, it doesn't latch. If I slam it a few times, it eventually latches, but only because the hinges become dislodged. At that point, it then becomes nearly impossible to reopen the seat, requiring a lot of pushing down and shimmying, to eventually get it loose enough to pull open. Has anyone else experienced something similar? What should I be looking for to diagnose the problem, and what might a suitable solution involve? I'm a fairly new rider, so any advice would be greatly appreciated.


    Thanks for anything you might have to offer,
    Dov

  2. #2
    Registered User lmo1131's Avatar
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    Can you take a few pics of the set-up.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    Registered User toooldtocare's Avatar
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    If my memory serves me right from the last time I put a new seat on an airhead (1995 RT), I had to remove the pin that goes into the latch from the stock seat and install it in the Corbin I bought. This pin also has a rubber "cone" over it that slips off. This pin screws into the seat. If you unscrew it a bit to make it longer it will go into the latch further, making it easier to lock. Also, there are rubber bumpers on the bottom edge of the seat. When I replaced them on my stock seat on my 1978 RS I found they came in two thicknesses. I do not remember where the small ones went vs. the taller ones, so you may want to look at a parts diagram to see. They will compress over time and make it easier to close the seat too.

    Wayne

    edit
    Photo stollen from Ebay shows a pin and cone I am talking about.
    Attached Images Attached Images

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    Thanks for the replies, so far. toooldtocare, that's definitely what my pin looks like. I'll take another look, and try extending it if necessary. If that doesn't help, I'll report back with pictures of the frame and seat.

  5. #5
    rabid reader dbrick's Avatar
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    Perhaps the latch assembly is gummed up. With the seat up, make sure it works smoothly.
    David Brick
    Santa Cruz CA
    2007 R1200R

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    Quote Originally Posted by dbrick View Post
    Perhaps the latch assembly is gummed up. With the seat up, make sure it works smoothly.
    It was a little gummed up at first, but some WD-40 cured that, so the push-button is working smoothly now.

  7. #7
    rabid reader dbrick's Avatar
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    I also like looking at the presence (or absence) the rubber bumpers. When the seat is latched in placed, it's actually supported by the bumpers, not the latch.

    I had a missing rubber piece on my R12R's seat recently, and the slight change in alignment made the seat more difficult to place and latch. Perhaps you could compare yours to another bike of similar seat and vintage.
    David Brick
    Santa Cruz CA
    2007 R1200R

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    I tried loosening the latch pin with a vise-grip, but had no luck. I also noticed that yes, it does have three rubber bumpers (one of which fits over the latch pin). When I'm trying to get the seat pressed shut, the rear bumper makes contact with the frame, but the front one does not. I've posted a couple of pictures below showing the overall setup and a closeup of the latch pin with the rubber bumper removed from it.

    Any tips on how to twist that latch pin out of there? I'd also like to verify whether it does, in fact, come out (the picture certainly looks like it) before I tear into the metal any more than I already have. I also added grease to the inner workings of the latch mechanism, so that should stay smooth.

    Seat and frame:
    Seat and Frame.jpg

    Latch pin:
    IMG_0552.jpg

  9. #9
    Registered User toooldtocare's Avatar
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    On the bikes that I have replaced the seat with a Corbin, the pin would unscrew. Those were mono-shock bikes. On my R90S and 78 Motorsport I left the factory seats on, but I BELIEVE they also unscrewed. Right now I am between airheads, so I cannot look. But, remove the cone bumper and see if the seat latches. It sounds like the bumper or latch is keeping it from latching. Maybe someone else could look at their seat to see if it unscrews an dual shock bikes. You can also try some penetrating oil on it too overnight.

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    Registered User lkchris's Avatar
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    Many aftermarket batteries are too tall.

    Have you tried without the tool tray in place?
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

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    Quote Originally Posted by toooldtocare View Post
    You can also try some penetrating oil on it too overnight.
    What do you mean by penetrating oil, and on which part of the mechanism? I sprayed some of this in the latch mechanism a couple nights ago: http://www.wd40specialist.com/produc...ithium-grease/

    The latch button is moving pretty well at this point.


    Quote Originally Posted by lkchris View Post
    Have you tried without the tool tray in place?
    Yeah, I tried without the tool tray, with no difference.

  12. #12
    Registered User toooldtocare's Avatar
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    Sorry, on the pin. I do not see threads, so either it is screwed all the way in, or it is welded. Maybe the oil will loosen the pin.

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    Registered User lmo1131's Avatar
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    The WD-40 product you sprayed on is a LUBRICANT (grease), not a "penetrating oil". I would be surprised if it was able to actually work it's way into (penetrate) the threads and loosen the parts.




    These are "penetrating" oils. There are others.

    WD-40


    Kroil


    PB Blaster


    Liquid-Wrench


    You will want to spray the penetrant around the base of the stud where it enters the seat base; it will wick into the thread by capillary action. It won't be an instantaneous fix and will probably need to sit over night at the least. Re-apply the oil occasionally



    #11 is stated to be a hex nut. If so, then the seat cushion may need to be removed to get a wrench on it. > http://www.ascycles.com/Illustrated_...FWSCQgod1FEAmA

    Last edited by lmo1131; 05-21-2013 at 05:42 PM.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  14. #14
    Registered User toooldtocare's Avatar
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    I just looked again at Max BMW parts listing and do not see the seat pin for your bike like I do for the mono-shock bikes. I then looked at the Corbin seat for the RT and see that it comes with the seat pin. Gives me reason to doubt that your pin is removable. No way of telling unless you remove the fabric. Did you try it without the cone bumper yet? if it works, you may be able to trim it down a bit to get it to latch.

    Wayne

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    Quote Originally Posted by lmo1131 View Post
    The WD-40 product you sprayed on is a LUBRICANT (grease), not a "penetrating oil"
    Thanks for clarifying what a "penetrating oil" is. I'll try some WD-40 (original) on it, and see if that works some magic overnight.

    Quote Originally Posted by toooldtocare View Post
    Did you try it without the cone bumper yet?
    Unfortunately, yes, I did try without the cone bumper and it made no difference.

    I think that at least part of the problem may be the right hook (#14 on the parts diagram Lew posted above) on the seat. When the left hook sits all the way over the pin on the frame that holds it in place, the right one sits a little to the right. I need to look at that more closely and see if I can possibly straighten it or something.

    Also, I found the parts catalog (fiche) from A&S (slightly different than the one shown above, but correct for the '81) and MAX BMW, which shows an image of the "cushion" (below). As Wayne pointed out above, it looks like the pin may be permanently attached to the seat (although that photo also shows only one hook). If so, I'll have to look at the hooks and bumpers, and see which of those may be misaligned.

    Again, thanks for all the help, you guys. I greatly appreciate it.

    52531237834_3_B.jpg
    Last edited by thedov@me.com; 05-31-2013 at 05:29 PM.

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