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Thread: 1990 K75S - Opinion on final drive? Good, bad or indifferent?

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    Registered User scottishsg's Avatar
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    1990 K75S - Opinion on final drive? Good, bad or indifferent?

    Drained the fluid from the final drive project today as well as oil change and transmission oil change. Looked as though they were original fluids. Never seen oil so black as what came out of the engine sump. Back to the original point...the final drive drain plug was caked in crud. Didn't appear to be metallic. Just.....sludge? Anyway, heres a couple of pics. Does this look good to lube up and reinstall? I appreciate your advice!!!

    100_0997.jpg100_0999.jpg

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    Benchwrenching PGlaves's Avatar
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    But black sludge could be a moly additive. If pasty I wouldn't worry about it, but would change oil again after a few thousand miles.

    Those splines look excellent.
    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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    Registered User scottishsg's Avatar
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    Thank you!! That is a great relief!! I will definitely drain the oil again after putting some miles on. Cheap insurance to be sure!

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    Still plays with trains. tinytrains's Avatar
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    How many miles on those splines?

    Here are mine at 71K miles. Some day I need to get the clutch. It shifts fine, but I am sure after 25 years they can use some grease.

    Splines_B_060113sm.jpg
    Splines_A_060113sm.jpg
    1988 K75 Low Seat
    2009 R1200R Roadster

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    Mars needs women! 35634's Avatar
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    Those splines look great! Load them up with honda moly 60 or whatever and don't worry about them.
    1987 K75S
    Original litter
    Original owner
    2012 Ural Gear Up

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    Registered User scottishsg's Avatar
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    Quote Originally Posted by tinytrains View Post
    How many miles on those splines?

    Here are mine at 71K miles. Some day I need to get the clutch. It shifts fine, but I am sure after 25 years they can use some grease.

    Splines_B_060113sm.jpg
    Splines_A_060113sm.jpg
    Yours look brand new!!! Obviously a well maintained machine! I am not sure exactly how many miles are on mine. The odometer reads 24k, but apparantly the speedometer does not work so could have 200k for all I know. If I had to estimate based on talking to original owner, she only rode it for about a year after the speedometer quit. So more likely in the 30k range. Been parked for last 10 years, so as you can imagine, I am dismantling and replacing anything rubber, right down to the injector o-rings. I want the first time I fire her up to also be the first time I ride her!

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    Registered User scottishsg's Avatar
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    Quote Originally Posted by 35634 View Post
    Those splines look great! Load them up with honda moly 60 or whatever and don't worry about them.
    Thanks for your input! Funny enough it was Honda Moly 60 I purchased last week for the splines. Was looking for some Wurth 3000 also as I read somewhere that a 50/50 blend is pretty good for these drive shafts. I am about to do a search for lubing the splines to see how much lube I am supposed to put on there. Just a light coating or pack it in there

  8. #8
    3 Red Bricks
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    Pack it in. Fill the grooves in both the driveshaft and on the pinion of the final drive.

    Redo it at LEAST every rear tire change.

    You can pull the driveshaft by clamping a hose clamp around the snout of the shaft and prying between the screw bump of the clamp and the end of the swingarm (being careful not to put a nick in the end of the swingarm). There is a tension ring at the forward end that will release. A light coat of grease on the forward end splines is fine (this end virtually never wears because the tension ring allows no sliding action. When reinstalling, a moderate rap on the end of the driveshaft with a mallet should seat the ring so that you can't pull the shaft out by hand.

    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 scottishsg's Avatar
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    Thanks Lee!
    Now that I have it down as far as I have it, noticed the clutch boot is leaking, and the swinga boot is torn. Will replace both, but considering pulling off the gearbox while I'm there and possibly replacing clutch or at least look at everything. Is that overkill? What you think?

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    3 Red Bricks
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    Lubing the clutch splines is something that should be done around every 40,000 miles. Probably would be a good time to do it, since the bike is new to you.

    Clutch discs last a LONG time (usually well over 100k, unless they get oil on them). If it's dry in there, the disc is almost certainly good.

    Change the O-ring that is behind the nut that holds the clutch housing (flywheel) on. This is usually the source of 90% of leaking inside the intermediate housing (bellhousing) and it drips directly onto the clutch disc. They dry out and crack, so put a new one in while you're there and it should be good for another 10-15 years.

    When lubing the clutch splines, add lube to the tranny input splines ONLY!!!

    Any grease put on the internal clutch disc splines will be pushed forward by the tranny input shaft and sling out onto the clutch disc (not good). Anything on the input shaft that is pushed back by the offset back end of the clutch disc hub will sling harmlessly to the rear of the friction surface.




    Last edited by 98lee; 09-23-2014 at 12:54 AM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  11. #11
    Registered User scottishsg's Avatar
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    Thank you for that advice Lee, and my apologies for the tardy reply! I am awaiting delivery of the guide pins for transmission. I'm a big believer in using the correct tools for the job when possible. Will have it out next Saturday and if you don't mind will post a pic or two of the innards for your input. Any advice is greatly appreciated!

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