1978 R100S :: final tweaks?

Discussion in 'Airheads' started by mspa, Aug 26, 2012.

  1. mspa

    mspa Been here awhile

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    I'll keep an eye on them, and when I'm about ready for servicing the forks, I'll do it all at once. Makes perfect sense what you say about getting int to do one thing and before you know it, you are in DEEP.

    I have to start compiling a list of maintenance stuff to order in the near future. I'll get some more plugs then. They are certainly easy to swap, so no worries there.

    My first priority now, and quickest win-win, is dealing with the barbacks. In a couple months, maybe less, I'll be visiting Wirespokes :)
    #21
  2. disston

    disston ShadeTreeExpert

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    Gee, he might even take a bath for that.
    #22
  3. mspa

    mspa Been here awhile

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    I hope he does :)

    So new concern popped up. During warmup at work this evening before coming home, I noticed the steering cap nut vibrating a little and moving counterclockwise, as in loosening :huh

    I tightened by hand as best I could and rode home. I get home and take a closer look and end up removing it to see what's under it and make sure there is no damage. I notice with the cap off, the tube inside is not aligned, unless I pull up on the forks a little. Putting the cap back on, I realize that in order for the cap to seat on the triple tree, I need to lift the forks to center that tube and I hand tighten to where you see in this photo.

    [​IMG]

    Another angle from top. I don't have a wrench that will fit or a socket. But I'm thinking about getting a socket tomorrow. Does anyone know what size the nut is? I found it on microfiche at Max BMW, and another site, but no size is mentioned. I'm sure I can go to O'Reilly's Auto and they'll let me take a couple of sockets out.

    [​IMG]

    Anything to be concerned about?
    #23
  4. supershaft

    supershaft because I can

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    I find those and the fork caps loose a lot. It's suppose to be torqued to 76ftlbs I believe. 36mm. Tightening the locknut will change your bearing preload! Keep track of that!
    #24
  5. mspa

    mspa Been here awhile

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    Here's where I show some ignorance . . . what is the bearing preload. I know some bikes have a dampner knob, so does preload act similar in slowing down the rate of steering motion?

    And is keeping track of that mean note in my riding journal when I torqued it to 76 ftlbs ?? Orrrr, maybe to keep an eye on it to make sure I tighten it again before it starts vibrating loose?

    So many questions :D

    I have notice the engine vibration increase, which is perhaps why seeing the cap nut vibrate was not so much a surprise . . . so I am assuming that it might be time to learn how to make some adjustments. I have Snowbum's (bmwmotorcycletech) article on synchronizing carbs . . . but that looks like a serious weekend learning experience that might be more fun learning with someone local who can show me. I'm one of those guys that learns visually, than by reading.
    #25
  6. mspa

    mspa Been here awhile

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    I now have a legitimate reason to swap the barbacks. I have to remove those to get a socket around the cap nut. Talked to the local BMW dealer and I'm not paying $100 to tighten. Torque wrench and socket will cost about $55-60, and I'll need again at some point . . . but since I have to remove the barbacks, I might as well put new risers in. I am concerned about the controls on my Superbike bar possibly getting in the way of the fairing upper braces, so I'm preparing myself for a more involved "fix" to the problem.

    I also want to get my Napoleon mirrors on, but don't want to mess with that until I know I'm keeping the current bar, grips, etc.

    As we know in mechanical things . . . one thing turns into many :D
    #26
  7. disston

    disston ShadeTreeExpert

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    There are two wrenches that belong in your tool kit for this. One is sometimes called the Dog Bone wrench. It has the 27mm socket on one end, for the swing arm lock nuts. And the 36mm box end wrench for the lock nut on top of the fork. The other wrench is a hook wrench that has two pins in one end, for the fork tube caps. And the hook wrench that fits the slotted nut under the nut you had come loose. You may use substitutes for these tools but the tool kit wrenches will do the job.

    Bearing Preload; Applicable to all tapered roller bearings. These are the bearings found in the wheels, the swing arm and the forks center stem (where you are having this problem). This bearing was invented by a Mr. Timken in the 1890's. You can Google Timken or roller bearing and find out all about them. They are maybe the most common bearing in the World. We use them in a lot of applications. The alternative is ball bearings which are inferior in this application, (but I believe they were used in the /2 bikes in this place.)

    Tapered roller bearings are installed so they have some sideways force applied. They are working primarily on the axis that they roll on. In other words a wheel bearing will rotate in the direction and in the plane you want to move and carry tremendous loads in that plane, thousands of pounds. But it is installed with a few pounds of force pushing at 90 degrees to the plane it rotates in. This few pounds of preload is usually somewhere between 3 and 7 pounds.

    Did you recently have replaced or replace the steering stem bearings? New bearings will seat themselves after as few as 50 miles and sometimes take a little longer, but not much. A bearing installed and properly preloaded will be loose after a while because it is a new bearing. The steering stem will knock as it goes up and down and the slotted nut and the top lock nut may come loose. This is probably what has happened.

    To properly fix this take stuff apart enough so you can get to the slotted nut with a hook wrench, tighten it and add 4 or 5 lbs of force to the wrench. It is not much. Over tight and the bearings will fail, too loose and the bearings will knock (also with a motorcycle you can get a tank slapper from too loose steering stem bearings.) Then, putting things back together when you tighten the lock nut, 36mm, hold the slotted nut in the opposite direction to prevent changing the preload.

    There is another caveat concerning the lock nut. It can have worn edges or faces where it meets the slotted nut. It will not hold if it is deformed. Look at it carefully.

    Good Luck.
    #27
  8. mspa

    mspa Been here awhile

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    I'll look again, but I didn't see anything like that. There are two wrenches with half moon shaped ends that I think are for adjusting rear shocks? But I'll check when I get home.

    Also, when I took the cap nut off, there was nothing between it and the triple tree top plate (if I'm describing it properly?). I did look at the collar on the nut and it did not look irregular.

    I've put on about 1000 miles in the last two months and I'm pretty sure the seller had recently overhauled part of the bike. I have no idea if that area was recent. I will talk to him when he gets back from vacation in a few days.

    I'll take some photos tonight and post. Thanks!
    #28
  9. disston

    disston ShadeTreeExpert

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    Maybe you can see the slotted nut under the top clamp. I can't see it in the picture you have post #23There's an awful lot of stuff on that bike to take everything apart. It is possible to tighten the slotted nut with out taking it all apart. The hook wrench you need is the one that has two pins in the other end for the fork tube caps. This wrench is thicker than most shock adjustment wrenches but it is thin enough to fit under the top clamp.

    If the nut was missing you could see the threads of the stem and I don't see them either so maybe it's just the grease that prevents us seeing what is happening here.

    Here's the pic of how it should be. #3 is the slotted nut. #4 is the top nut that came loose.

    http://www.realoem.com/bmw/showparts.do?model=0334&mospid=51651&btnr=31_0312&hg=31&fg=10

    #5 are the fork tube top caps that fit the pin wrench.

    If you don't have these two tools in your on board tool kit you need them. Hucky's is a good source for these. I think you have to call him because they aren't on his web site. Find out if you have those parts on your bike and look at the lock nut too because you may need that also.

    http://www.bmwhucky.com/
    #29
  10. mspa

    mspa Been here awhile

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    Okay, thanks!

    I have the factory toolkit and there isn't room for any more tools, so I assume it's complete. There is the wrench with two pegs on one end that I figured are for the fork caps. There is a similar style wrench with holes, not pegs, that I thought may fit with the other?

    I'm on my way home and I'll take a look and reply, possibly with another photo.
    #30
  11. mspa

    mspa Been here awhile

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    So here's my toolkit with the one tool you mentioned. The Koni shock adjustment tool is to the right (for those that don't know).

    [​IMG]

    Here's my cap nut. I see no slotted nut.

    [​IMG]

    top view

    [​IMG]

    You can see on this view my concern for using stock risers. The fairing supports would not be in the way of the bars once they are rotated back and down, and the controls would most likely clear, but I'm wondering about the cables. I will figure it out since I won't let those fairing braces ruin the party.

    [​IMG]

    [​IMG]

    side view

    [​IMG]

    [​IMG]
    #31
  12. boxerboy81

    boxerboy81 Stay Horizontal

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    The slotted nut is missing. It should seat below the flat steel triple clamp.
    #3 in the picture.


    [​IMG]

    You also need this...

    [​IMG]

    It might be wise to dismantle the lot and see exactly what's there and what's not. Hopefully the bearings are ok but seeing as the slotted nut is how you adjust the pre-load, they might not be in the condition they should be.
    #32
  13. mspa

    mspa Been here awhile

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    Does that mean I have to service the forks too . . . or possibly the bearings? This sounds like the bike may have to sit awhile. Bummer.
    #33
  14. mspa

    mspa Been here awhile

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    By the way, I really like the sound of these Whispertones . . . not really quite, but a nice and not too loud.
    #34
  15. boxerboy81

    boxerboy81 Stay Horizontal

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    The forks should be fine, but at the least you should install the slotted nut, maybe regrease the bearings then set the pre-load for the bearings and see how it feels.

    Whilst riding at 30mph with a loose grip, if too tight, the bike will feel like it wants to wander back and forth. If too loose, you'll get some headshake.


    You might get lucky.
    #35
  16. mspa

    mspa Been here awhile

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    Funny thing is it feels pretty good right now. Considering the front tire is on backwards as well, I can't wait to see how it feels when it's setup right.
    #36
  17. disston

    disston ShadeTreeExpert

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    I do think the wrench BB81 shows you should be in your kit. It is the 36mm needed for the top nut and also fits the fork legs at the bottom too. The collection of tools known as the on board tool kit is what ever you say it is. Get whatever tools you need. Have two tool rolls. You don't have to have tools in a tool roll anyway. But you need all the need tools.

    Take those barbacks off and you can then slip the hook wrench under the top clamp to feel if the slotted nut is there. Because you don't know what I'm talking about really and won't know what that is so the next step is to take the top clamp off. To do this remove what ever else is in the way and use the pin wrench, yeah, you have that one, and take #s 5 thru # 10 off. Both sides. Under the top clamp is the slotted nut.
    #37
  18. boxerboy81

    boxerboy81 Stay Horizontal

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    Disston, do you think it might be there? It looks like it's missing to me.

    mspa, wait 'til you get the tool pictured above before you try dismantling anything. Getting the fork top nut off is a bugger without that tool. You're in danger of rounding it off and being unable to remove it and the language in the shed gets worse and worse when that happens and the replacement top nuts then cost...

    When tightening the top bolts, ensure you use a torque relief method otherwise you risk misaligning the forks..
    [​IMG]






    .
    #38
  19. mspa

    mspa Been here awhile

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    Guys, I don't think it's in there. If it is, it's covered in grease. Maybe I'll have time tomorrow to check in there a little bit.
    #39
  20. disston

    disston ShadeTreeExpert

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    I was the one that spotted that it is not there. Read back a few posts. But the area is pretty greasy under the top clamp so maybe it is there only covered with grease. It's pretty hard to imagine the bike being rideable if the slotted nut is missing, isn't it? But I can't see it. And I can't see the threads either so maybe it's covered with grease.

    If it is there it needs adjustment and possibly cleaning/greasing. The bearings are supposed to be cleaned and greased once in awhile. Some riders do this every year which I don't really think is over doing it but is more than I do it. I'm just a little lazier than most.

    He's got the top nut off already. It was loose which is what started this. A 36mm socket is fine but doesn't fit in the tool roll very well especially with the 1/2" driver. There is a 36mm box end Suzuki or Kawasaki wrench that is much heavier than our Dog Bone wrench.

    I'm pretty sure you will have to take the top clamp off and look/see what is there. Then clean/grease both the bearings. Simple.
    #40