LC4 Sprocket seal replacement...

Discussion in 'Thumpers' started by creeper, Oct 29, 2005.

  1. bikemoto

    bikemoto Tyre critic

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    If you have the domed washer and bolt system, yes replace it every time.

    If you have the permanent 27 mm alu nut and lock washer - what we were discussing :-) - use 60 Nm and Loctite 243.
  2. meat popsicle

    meat popsicle Ignostic

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    Ah so, my apologies. :beer
  3. clintnz

    clintnz Trans-Global Chook Chaser

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    Indeed! Goes without saying on a 640 dunnit? :lol3

    I replace the alu nut every 4 or 5 sprocket changes along with the alu nut on the rear axle. They are kinda important & alu does wear & fatigue eventually. Given that they're not the sort of thing you can buy at the local hardware shop, & your KTM dealer might not even stock them, it's nice to have spares on the shelf.

    Cheers
    Clint
  4. bikemoto

    bikemoto Tyre critic

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    Good plan!
  5. Motohorse

    Motohorse ***erator

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    I have a couple of questions for anyone who is savvy with respect to seal and o-ring sizes.



    Does anyone know whether the shaft seal is a generic seal which can be found outside of KTM dealers?

    Is 25mm the o-ring internal diameter or external diameter? Would NBR/Silicone/Neoprene all be identical for this application.

    Please chime in if you have any knowledge of this!
  6. gunnerbuck

    gunnerbuck Island Hopper

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    Yes, pretty much all the seals on these bikes are generic and available from a bearing supply.. The same goes for all the bearings except 2..

    The 25mm is the inside diameter.
  7. Motohorse

    Motohorse ***erator

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    I had to drill the oil seal three times to get it out. After pulling the small wood screw I threaded into the hole way harder on then I should have needed to, I finally removed the old seal.

    The new seal will not seat straight. I'm wondering whether it's bent and should be replaced. I did botch the first attempt and spent half an hour trying to remove the new seal after seating it incorrectly.

    The inside of the crank bore looks fine. Am I doing something wrong? Is the new seal bent? Please help me out.
  8. gunnerbuck

    gunnerbuck Island Hopper

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    If it is a tough go , try putting the seal in the freezer and then warm the case to expand it, this will buy you enough differential that the seal should go in a lot easier...
  9. Motohorse

    Motohorse ***erator

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    Thanks for the tip. I'll try it tonight.

    I know that these seals have a steel band along the diameter. Is it plausible that gently tapping it with a mallet and then removing it could have bent the seal lip?

    I can't tell if the seal is now ever-so-slightly bent and am wondering if I need to try the heat/freeze trick on a new seal.
  10. Motohorse

    Motohorse ***erator

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    The new seal wouldn't seat, even after freezing.


    I'm grabbing a new seal today. I'm hoping that the last one was just bent and that the bore isn't uneven.
  11. bmwktmbill

    bmwktmbill Traveler

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    If freezing doesn't work try lube and your thumbs to get it started straight, then use a piece of sawed off broom handle to gently tap it in.
    That might take a few trys but maain force is not th key.
    Work around it gently to keep it from binding while tapping it into place.

    I have lubed and tapped many into place, never had a problem.

    b
  12. Motohorse

    Motohorse ***erator

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    I dunno man, there must have been some inconsistent globs of metal on the inside lip on the bore.

    When I took the old seal out I noticed a slug of metal around the lip of the bore. I needed to sand it down a bit. It didn't go all the way through the bore so it won't affect oil retention.

    After sanding, I used a new seal, reversed the sprocket and used a mallet on the sprocket to drive the seal in straight. (I'm surprised that this hasn't been mentioned -- must be the easiest way to have it seated straight without special tools)


    It went in, but it took very firm hammering over the course of an 40 minues or so.

    I think it may still be leaking somewhat, but the weeping from these bikes is starting to seem impossible to fix 100%. In fact I just noticed a significant amount of oil collecting below the kick-starter shaft.

    In the last few weeks I've resealed the rocker cover, replaced the oil seal, replaced the clutch master (and the slave soon before) and tried using some Threebond 1211 on the timing window. It's impossible to stop all the weeping in my experience.


    Sometimes when the bike weeps, I weep,


    Our pain is shared

    :'(
  13. Grreatdog

    Grreatdog Long timer Supporter

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    Do you replace the inner sleeve and o-ring when you do the job? In my experience the inner sleeve develops a groove along the seal and will continue to leak even with a new seal. So, to me, that is a wear item on KTM's. I always replace the sleeve, o-ring and seal together. Both EXC's I did haven't leaked a drop since. My 640 still doesn't leak so it can wait a while yet.

    Also, a $10 seal puller from any auto parts store saves a lot of effort and a lot of potential damage doing this job. i bought one because this is a common enough job on KTM's that I am not risking damage pounding in screwdrivers or any other homemade efforts to pull these seals. They pop right out with the correct tool.
  14. Motohorse

    Motohorse ***erator

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    The sleeve/bushing was in the same condition as creeper's at the time he posted the guide so I kept it.

    The old oring had completely disintegrated so I replaced it.
  15. gunnerbuck

    gunnerbuck Island Hopper

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    You need to use a retaining compound on the timing window, not 1211 if you want it to stay oil tight... Loctite 648 works good for that...

    The outer seal on the countershaft is usually good for a whole lot of miles and like others have mentioned it is the O-ring that usually will cause an oil weep.. The O-ring will last me the life of a chain/sprocket set without weeping and is easy to change so anytime I have the countersprocket off I make a point to change it out...

    Premature failure of the O-ring is often caused by running the chain too tight...

    The kickstart seal can also be changed fairly easily, I outlined how I did it in this thread: http://advrider.com/forums/showthread.php?t=732362&page=7

    I saw a posting where I fellow made a nifty seal puller for that seal out of a jigsaw blade, that would be the way to go..
  16. Grreatdog

    Grreatdog Long timer Supporter

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    Dirt cheap and they work.

    [​IMG]
  17. regder

    regder Adventurer

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    My sprocket seal seeped for about 50km after I replaced it, before stopping. Been good for about 1000km so far. Maybe it wasn't seated fully?

    Here I thought I was the only one in the leaky KTM club. Did the sprocket seal. Still have to do the rocker cover, kickstart seal, and possibly the neutral safety switch. Those are the leaks I know about, god knows how many more there are.
  18. Motohorse

    Motohorse ***erator

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    My neutral safety switch went out some months back. I have a new one coming in the mail.

    Can't see how safety switch failure and leakiness might be causally related though.
  19. regder

    regder Adventurer

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    Mine works, it's just leaking a little bit of oil
  20. VanFitz

    VanFitz Adventurer

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    I'm having a hell of a time finding replacement parts. Do you have a source and/or the dimensions for the parts?

    Any help you can provide will be hugely appreciated.

    Cheers,

    Fitz