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Thread: '90 k75s steering head bearing adjustment

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    '90 k75s steering head bearing adjustment

    So it is my understanding that the steering head bearings have to be adjusted/tightened every 5-6,000 miles. I ride a lot, so rather than pay a mechanic every month or so, I'd like to perform this service myself, but I have had a great deal of difficulty finding the appropriate information about this. Any help would be appreciated.

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    Quote Originally Posted by cniccore View Post
    So it is my understanding that the steering head bearings have to be adjusted/tightened every 5-6,000 miles. I ride a lot, so rather than pay a mechanic every month or so, I'd like to perform this service myself, but I have had a great deal of difficulty finding the appropriate information about this. Any help would be appreciated.
    Good heavens, I hope it's nowhere near that often. If it is, it's a wonder I can steer in any direction at all.
    2000 R1100RT / 1987 K75C (RIP) / Santa Clarita, CA

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    Benchwrenching PGlaves's Avatar
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    I bought a K75 in 1986. I wrecked it in 2005. In the 370,000 miles I rode that bike I adjusted the steering head bearings exactly twice. Whoever needs to adjust them every 5 or 6K miles isn't doing something right.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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    Quote Originally Posted by PGlaves View Post
    I bought a K75 in 1986. I wrecked it in 2005. In the 370,000 miles I rode that bike I adjusted the steering head bearings exactly twice. Whoever needs to adjust them every 5 or 6K miles isn't doing something right.
    If I am not mistaken you have written many tech articles here, and are known far and wide for your vast knoledge on the subject of motorcycle maintenance, and repair. I actually read articles you wrote about the K75 before I owned one, so I have a tremendous amnount of respect for your opinion.
    Can you point me in the proper direction that might lead me toward a resolution. I was having an issue with my k75s where cornering at higher speeds, say 75-85mph it feels like I am riding a fish. At lower speed, if I encounter even small bumps in the road with my hands off the handle bars, or if I slap one side of the handle bars at slow speed, the handle bars will wobble quite violently. Now I understand that I shouldn't be riding without my hands on the bars, but it seems that this might be indicative of a greater problem. The rear shock is less than a year old, it is a Progressive, and the steering head bearings, and fluidbloc damper where replaced in Nov. I had the head bearings adjusted a month ago and the problem was eliminated for a while, but after a 1500 mile ride it has returned. The mechanic that replaced the bearings and fluidbloc has suggested that the issue is that my rear shock is too stiff. What confuses me is that the issue was eliminated after adjusting the bearing, and has no returned.
    Thanks for your assistance in advance.

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by cniccore View Post
    If I am not mistaken you have written many tech articles here, and are known far and wide for your vast knoledge on the subject of motorcycle maintenance, and repair. I actually read articles you wrote about the K75 before I owned one, so I have a tremendous amnount of respect for your opinion.
    Can you point me in the proper direction that might lead me toward a resolution. I was having an issue with my k75s where cornering at higher speeds, say 75-85mph it feels like I am riding a fish. At lower speed, if I encounter even small bumps in the road with my hands off the handle bars, or if I slap one side of the handle bars at slow speed, the handle bars will wobble quite violently. Now I understand that I shouldn't be riding without my hands on the bars, but it seems that this might be indicative of a greater problem. The rear shock is less than a year old, it is a Progressive, and the steering head bearings, and fluidbloc damper where replaced in Nov. I had the head bearings adjusted a month ago and the problem was eliminated for a while, but after a 1500 mile ride it has returned. The mechanic that replaced the bearings and fluidbloc has suggested that the issue is that my rear shock is too stiff. What confuses me is that the issue was eliminated after adjusting the bearing, and has no returned.
    Thanks for your assistance in advance.
    You are describing two problems. High speed cornering that induces what feels like a wallow is usually caused by inadequate slow speed damping (little compressions opposed to sharp bumps) as the shock compresses and rebounds under cornering loads. That might be translated as too stiff a spring because the damping of spring rebound needs to match the stiffness of the spring. If the shock is adjustable you need to increase the damping. If not, then you need to replace the shock or have it rebuilt if that is possible for your shock make/model.

    The second problem is the wobble you feel on bumps or slapping the bars. That indicates that the steering head bearings are loose and/or the Fluidbloc isn't working correctly. Since new bearings were installed I would suggest that they be readjusted. Some manuals advise readjusting steering head bearings 50 or 100 miles after they were installed. That is good practice but almost nobody does it. When the races are installed they might not be totally seated even though they seem that way. Readjusting the bearings after a run-in is good practice even without symptoms. Given you symptoms.

    1. Deal with the shock issue: adjust damping, rebuild, or replace
    2. Have the steering head bearings readjusted.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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    Quote Originally Posted by PGlaves View Post
    You are describing two problems. High speed cornering that induces what feels like a wallow is usually caused by inadequate slow speed damping (little compressions opposed to sharp bumps) as the shock compresses and rebounds under cornering loads. That might be translated as too stiff a spring because the damping of spring rebound needs to match the stiffness of the spring. If the shock is adjustable you need to increase the damping. If not, then you need to replace the shock or have it rebuilt if that is possible for your shock make/model.

    The second problem is the wobble you feel on bumps or slapping the bars. That indicates that the steering head bearings are loose and/or the Fluidbloc isn't working correctly. Since new bearings were installed I would suggest that they be readjusted. Some manuals advise readjusting steering head bearings 50 or 100 miles after they were installed. That is good practice but almost nobody does it. When the races are installed they might not be totally seated even though they seem that way. Readjusting the bearings after a run-in is good practice even without symptoms. Given you symptoms.

    1. Deal with the shock issue: adjust damping, rebuild, or replace
    2. Have the steering head bearings readjusted.
    OK, I understand that the shock needs to be replaced, it is as soft as I can make it. But what I don't understand is:
    1) why did the wallow go away after the head bearings were adjusted a month ago
    2) could the stiffness of the rear shock be causing the head bearings to loosen, or is it more likely that the bearing improperly adjusted? That shock is so stiff, that it has been referred to as a piece of oak, or maple.
    Thank you again.

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by cniccore View Post
    OK, I understand that the shock needs to be replaced, it is as soft as I can make it. But what I don't understand is:
    1) why did the wallow go away after the head bearings were adjusted a month ago
    2) could the stiffness of the rear shock be causing the head bearings to loosen, or is it more likely that the bearing improperly adjusted? That shock is so stiff, that it has been referred to as a piece of oak, or maple.
    Thank you again.
    Setting the shock on minimum preload lowers the rear of the bike, increasing the steering head angle vs perpendicular to the ground. You have a hydraulic damping issue - probably not a preload issue. Nothing at the back of the bike will loosen the steering head bearings. But simply seating-in of the races and running in of the bearing can cause it to need to be readjusted. If your shock is that stiff then it is binding, capturing the back of the bike in a compressed position. Nothing will feel right until the shock is replaced. Do that first. Then proceed from there. The wobble after the whack-a-bar still indicates looseness in the steering head. The two problems boith affect the handling but are not really related.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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    Quote Originally Posted by PGlaves View Post
    Setting the shock on minimum preload lowers the rear of the bike, increasing the steering head angle vs perpendicular to the ground. You have a hydraulic damping issue - probably not a preload issue. Nothing at the back of the bike will loosen the steering head bearings. But simply seating-in of the races and running in of the bearing can cause it to need to be readjusted. If your shock is that stiff then it is binding, capturing the back of the bike in a compressed position. Nothing will feel right until the shock is replaced. Do that first. Then proceed from there. The wobble after the whack-a-bar still indicates looseness in the steering head. The two problems boith affect the handling but are not really related.
    Agreed, Thank you very much for your input. Now, can you tell me where I might find a water/oil pump housing/unit for less than $400?

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by cniccore View Post
    Agreed, Thank you very much for your input. Now, can you tell me where I might find a water/oil pump housing/unit for less than $400?
    Beemer Boneyard, Repsychle, or any of the other few used re-cyclers.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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    K100RS 85 w 148k mi. I replaced my head bearings and use special tool to tighten

    I bought and have a tool to tighten the knurled nut with the tank on.

    Channellock makes a "oil filter wrench"

    It can grip the knurled nut to snug it which takes out the wobble you get when the bearings are new and "seating" as Paul stated.

    http://www.channellock.com/oil-filter-pvc.aspx they sell three sizes, mine are #215 and are 16" long "closed." It takes hand strength and protect your tank with a some electrical tape. Soon after replacement it took some tightening over several months to get the wobble out. Of course you loosen triple clamps first so they can move closer together as you tighten the head bearings. Good luck.

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    Registered User jwetering's Avatar
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    Quote Originally Posted by PGlaves View Post
    You are describing two problems. High speed cornering that induces what feels like a wallow is usually caused by inadequate slow speed damping (little compressions opposed to sharp bumps) as the shock compresses and rebounds under cornering loads. That might be translated as too stiff a spring because the damping of spring rebound needs to match the stiffness of the spring. If the shock is adjustable you need to increase the damping. If not, then you need to replace the shock or have it rebuilt if that is possible for your shock make/model.

    The second problem is the wobble you feel on bumps or slapping the bars. That indicates that the steering head bearings are loose and/or the Fluidbloc isn't working correctly. Since new bearings were installed I would suggest that they be readjusted. Some manuals advise readjusting steering head bearings 50 or 100 miles after they were installed. That is good practice but almost nobody does it. When the races are installed they might not be totally seated even though they seem that way. Readjusting the bearings after a run-in is good practice even without symptoms. Given you symptoms.

    1. Deal with the shock issue: adjust damping, rebuild, or replace
    2. Have the steering head bearings readjusted.
    Thank you for describing a problem I have been having since the start of the riding season. I also get a wallow when I corner at high speeds, especially if I encounter a bump.

    In my case - I rebuilt the front fork tubes over the winter. Actually I didn't rebuild them so much - I took the sliders off, cleaned them thoroughly, changed the oil, and changed the seals. I also changed my steering head bearing and have it tightened too what I think is satisfactory. I did not touch the back shock which is a relatively new Progressive 412.

    There's more colour. In fact the fork tubes were used. My original fork tubes were wrecked in a low speed crash. The used fork tubes were from an S and were straight and clean. I don't know what springs were inside - and I don't know what springs were inside my old tubes. One or the other could have been not stock for all I know.

    I attributed the problem to a badly cupped front tire. In the past this has resulted in wobbles when I let off the gas and let go of the handlebars - but that's not a problem this time. The wobble problem only shows up in corners. I did change my tire recently - I put on a used tire which was in pretty good shape. It definitely handled better and I thought I had it beat but just last night it gave me another wobble which has me concerned.

    So here's a question..if I overfilled the forks a bit - would that cause what we describe. I think I may have put 50 mL too much in.

    thanks
    jasper
    north vancouver

    1990 K75S

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    Quote Originally Posted by cniccore View Post
    Ithe steering head bearings, and fluidbloc damper where replaced in Nov. I had the head bearings adjusted a month ago and the problem was eliminated for a while, but after a 1500 mile ride it has returned. The mechanic that replaced the bearings and fluidbloc has suggested that the issue is that my rear shock is too stiff.
    What did the mechanic pack the fluidbloc with??

    The proper grease has not been available from dealers for years.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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    Quote Originally Posted by jwetering View Post
    I also get a wallow when I corner at high speeds, especially if I encounter a bump.


    So here's a question..if I overfilled the forks a bit - would that cause what we describe. I think I may have put 50 mL too much in.

    thanks
    FIRST drain the forks into a clean container. Then refill to the correct amount for your year bike (270-290cc or ml. OR 9.23-9.8 fl. oz.).

    Try it.

    If you still have issues with high speed wallow, bump up the rear preload. If everything else is correct, bumping up the rear preload on the 412 works well. When sitting on your bike with all your weight on it, the exposed shock shaft should be no more than 1-1 1/4 Inches shorter than how much is exposed with the bike on the centerstand if you have the 14" stock length 412-4015B shock.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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    Registered User jwetering's Avatar
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    Quote Originally Posted by 98lee View Post
    FIRST drain the forks into a clean container. Then refill to the correct amount for your year bike (270-290cc or ml. OR 9.23-9.8 fl. oz.).

    Try it.

    If you still have issues with high speed wallow, bump up the rear preload. If everything else is correct, bumping up the rear preload on the 412 works well. When sitting on your bike with all your weight on it, the exposed shock shaft should be no more than 1-1 1/4 Inches shorter than how much is exposed with the bike on the centerstand if you have the 14" stock length 412-4015B shock.


    Thanks Lee - I'll drain and refill the forks this weekend. I tried cranking up the rear already - it made no difference. In fact I just recently backed it down a notch. It's one click off the maximum now. The rear shock is definitely not too soft. It's barely a year old and plenty firm.

    jasper
    north vancouver

    1990 K75S

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    To the OP, what about tire pressures? A severely underinflated tire can cause the wallows. Also, how about swing arm bearings? Do you have any slop in the swing arm, side to side? And for that matter, wheel bearings also.

    If the head bearings are loose, they may be binding as the yoke is misalaigned ever so slightly, and that can cause wallowing also, as the steering becomes jerky instead of fluid-like.
    Mike Davis
    "Old n Slow" It's a way of life!
    1985 K100RT

    1998 R1100RT

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