My '83 R65 Front 'clunk' over potholes. Driving me CRAZY

Discussion in 'Airheads' started by bikerlt, Aug 30, 2008.

  1. Foot dragger

    Foot dragger singletracker

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    Try riding a /6 if you want to see how bad forks can work,clunking,clanking,binding when you hit a big bump leaned over.They are the worst Ive tried by far.Other owners say you'll get used to it,they dont even notice it anymore. I was probably trying to ride it too fast but still...................................Ive had a 73 Norton that was better then that. One thing for sure BMW doesnt build the insides of those forks like any other,out of stubborness or? Its all part of the character of the bike I think.
    #21
  2. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Yours may have needed rebuilding badly, as when working properly, the /5, /6 and /7 (before the Brembos) work very well. From what I've been told, they're much more sophisticated than the 81-4 models with the Brembos. I'm actually surprised you have that opinion. Did you know that BMW was the first to come out with hydraulic front suspension in the 30s? Sometime around then.
    #22
  3. bikerlt

    bikerlt Banned

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    Well, with all respect to phactory (I mean that), I've been disuaded from updating the fork components following a long conversation with a very reputable parts guy (who I won't name just in case this is contentious). After he explained exactly what the upgrade was meant to remedy I realized that I had already accomplished the same with the addition of shims in the same area. When I told him this he agreed. The valve housing was never perfectly situated in the barrel and BMW knew that in order to keep it from rattling around they had to supply the dealerships with shims. This got to be a headache since you had to rely on each mechanic to get it perfect, so the upgrade just split the housing (the kit is referred to as a 'split housing' kit) and inserted a spring in between the two halves. No need anymore for shims, obviously. Otherwise, the valving was the same and damping response unchanged. If, as I have, the shims are adequately supplied to keep the original part from moving, then the update will not do me any good. DAMN.... DOUBLE DAMN!!!!!!

    This rattle/clunk is gonna end up being the Inspector Clouseau to my Commissioner Dreyfus. My eye is starting to twitch as I write this.
    AAArrrrrrggggghhhhhh. Help me!
    #23
  4. mark1305

    mark1305 Old Enough To Know Better

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    Now that you've decided against the upgrade, I'll play Devil's Advocate..

    What if for some reason your shim modification doesn't do the job as well as the "split housing kit" with its extra spring(if I'm reading the drawings correctly). If the parts only run $20 or $30 or anywhere under about $50, I'd gamble on it just to see what happens.

    Maybe that's why I don't have as much money as I do time any more - I have to go for it just to see the outcome :D
    #24
  5. bikerlt

    bikerlt Banned

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    mark1305 you've been reading my mind. I must add another layer of foil.

    Yeah, it would be nice to at least eliminate every possiblity. Ironic that this little ghost in my machine would have compelled me to learn about and repair so much in it. I've had, over time, 80 percent of the bike disassembled while trying to track this down.
    #25
  6. Uncle Ernie

    Uncle Ernie Long timer

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    there has to be a pony in here somewhere...!
    #26
  7. bpeckm

    bpeckm Grin!

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    :lol3 :lol3 :lol3 :lol3 :lol3
    #27
  8. phactory

    phactory Motorcycle Rescue

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    This is the post where I detail what gets swapped. #19, #11, and #20 go in and replace #14. #16 and #21 are both snap rings for two different production dates.

    You probably can remove some of the slop by shimming, and the available shims are shown in the drawing as #15. This is easy enough to check if you have your forks off and apart.

    But just shimming is no where near as effective as this kit, which cost a total of $15.44 (List price for all 6 pieces) and does not require shimming. I always felt that this was BMW's answer to the Anti_Dive Kits that Luftmeister used to sell.

    PhacK

    #28
  9. phactory

    phactory Motorcycle Rescue

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    Since it has been a couple of years since I have had my CS on the road I forgot exactly when my forks used to do the clunking. But the more I thought about it, I remembered that it was always at full extension over really bad bumps. To me that seems like that is when the damper rods get banged against the the existing PN #14.

    Now if #14 needs to be shimmed it can be quite a clunk. Even if shimmed properly it will still make noise when you hit that type of bump.

    What the kit does for you is to add some give (via the spring) to the damper rod if it does fully extend against the stop. For this reason alone I think the extremely small cost of this upgrade is worth it.

    PhacK
    #29
  10. squish

    squish Out of the office.

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    When I got my R80ST back in 91 or 92
    I found that it did this clunk.
    I freaked out. In those pre internet days (at least for us normal none geeks)
    You just had to ask around.
    And ask I did everyone who I could ask who I thought might know something.

    Finally I came down to the old
    "They all do that"

    Or in other words
    "BMW's are weird, we can't figure out how to make it not be weird so we put up with the weirdness for the sake of being able to ride the bike and not be driven Mad."

    I seem to recal that someone even mentioned that BMW sent out a TSB
    That pretty much said the clunk was standard at the extreme movements of the fork.

    It's interesting to note that my K-bike forked R80 (well really the wife's R80)
    Doesn't clunk.
    #30
  11. Cogswell

    Cogswell Spudly Adventurer

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    Ok, I have my forks apart to do this update/mod just in time to hurry up for the spring rally a few weeks away. The clunking has been quite annoying on full extension.
    I have gone over this thread for my part numbers, (Thanks Phack) and the one thing I cant seem to find is the large O-ring that fits in the bottom of the fork leg to seal the lower cap. Anyone have any ideas where I may find this culprit on the fiche ?

    TIA

    Mike
    #31
  12. mark1305

    mark1305 Old Enough To Know Better

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    Since this thread fell into obscurity, I'm pretty sure I've traced my particular clunk to the dash mount bracket flexing on sharp bumps. I can hold it with one hand and pull against it and silence the clunk over bumps that normally cause it.

    Now what is actually clunking under the plastic trim remains to be discovered. I can't find anything loose in there.
    #32
  13. Cogswell

    Cogswell Spudly Adventurer

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    Mark do you mean the mount for the instruments on the rubber bushings ?

    Other than that I'm stuck. Went to the local dealer and he tells me that
    part #31-42-2-301-885 is no longer available from BMW, so I may not be able to do the update unless I find a dealer with the parts covered in dust on the shelf.:becca


    Mike
    #33
  14. mark1305

    mark1305 Old Enough To Know Better

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    Mike, when I run that part number through the Max BMW fiche, its available for under $3 (remove the dashes to search part numbers). And its listed for a whole bunch of bikes. Valve housing down in the shock absorber part of the forks, correct?
    http://www.maxbmwmotorcycles.com/fiche/DiagramsByPartNumber.aspx?parts=31422301885%20

    In my case, yeah, the clunk is either the plastic fairing around the instruments or the instruments flexing the stamped sheet metal "Panel" that holds tach, speedo, and headlight. The headlight is held pretty rigidly, so I suspect a combo of instruments and plastic fairing bouncing and hitting over bumps.
    #34
  15. boxerboy81

    boxerboy81 Stay Horizontal

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    Try checking the wear on the large centre nut at the upper yoke.

    These can wear over the years. Remove it, and replace with a shim made from an alu drink can, applied over the forward facing surface. Does Grolsch come in a can?

    It's an easy test, and cheap to try. Might get lucky.
    #35
  16. Cogswell

    Cogswell Spudly Adventurer

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    Mark, I had the local dealer run it on "lightspeed" I think part locator and it showed NLA in the US and the Fatherland, he called BMW parts help in Jersey too.
    I spoke with Craig at Benchmark works yesterday afternoon and he said his parts source in europe shows it available. I will know in 3-4 weeks if it shows up. I may call a few others in the meantime in the event some are laying on the shelf somewhere.
    Hey I've got 3 weeks till the rally right, plenty of time.:lol3


    Mike
    #36
  17. Cogswell

    Cogswell Spudly Adventurer

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    Thanks, I'll check the clearance at the large center nut too.:thumb


    Mike
    #37
  18. spo123

    spo123 Man About Town

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    Rusty, at Max BMW in NH, is absolutely THE BEST PARTS MAN ANYWHERE!
    spo:jose
    #38
  19. Cogswell

    Cogswell Spudly Adventurer

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    I called and spoke with Rose yesterday, Rusty won't be back from vacation till tomorrow.:evil


    Mike
    #39
  20. rustygardhouse

    rustygardhouse rusty

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    So...

    How did this end?

    Smiles or tears?

    Did you find a source of 31 42 2 301 885 VALVE HOUSING?

    Got the same problem on my '80 R65 & looking for a fix.
    #40