RFS Countershaft Seal Replacement

Discussion in 'Thumpers' started by firerigger, Mar 30, 2010.

  1. firerigger

    firerigger Trauma waiting to happen

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    I have a leak from the countershaft seal on my RFS ('04 EXC 450), so I plan to replace it at my next service. What is involved? Do I need special tools? I'm pretty savvy (I do my own valve adjustments and such), I've just never done this particular repair before and I'm looking for some dos and don'ts before I get into it.
    #1
  2. Skowinski

    Skowinski Eukaryote

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    You will need at least the seal and the 0-ring that goes at the inner end of the bushing that the seal rides on. If the bushing itself has wear grooves then it will need replacing also. It's a fairly easy 30 minute or so, 1 beer operation, the main issues to watch for are 1) make sure everything is clean around the countershaft area before you start, 2) pull the bushing off the countershaft, the old 0-ring with either come out with it or be on the countershaft, 3) pry the old seal out with a seal puller, I got one from Sears (Craftsman 9-47645) and be careful to only grab the seal and not to gouge the bore it sits in, and 4) drive the new seal in straight, slowly, using a 32 mm socket (I think, from memory). There is no seat for the seal, so just drive it in until flush with the outside of the case. I'm sure others will chime in with what I've missed... :1drink
    #2
  3. GR0NK

    GR0NK Got some screws loose!

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    Skowinski has it pretty much explained.

    I would only ask first if you are using the right front sprocket (very common mistake) and if the bolt and cone washer are in good shape, as in coned and not flat.

    1. Some aftermarket counteshaft sprockets are too narrow and don't put any pressure on the spacer and o-ring. Without pressure, the oil leaks from between the CS and the spacer. Check that there is no side-to-side play with the bolt tightened.

    2. The washer behind the CS bolt should be cone-shaped to put pressure on the spacer and o-ring. These flatten out after a while. The bolt and washer come as a kit for about $3 and the bolt is even pre-threadlocked.

    3. The spacer is steel so it is pretty rare to see one with a groove in it from riding on the seal but I suppose it can happen. If the seal surface isn't flat, just replace it with a new seal and new o-ring.



    Sean :bmwrider
    #3
  4. Off the grid

    Off the grid Unsmooth Operator

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    Mine just started weeping after I swapped out the front and rear sprockets/chain. A buddy told me that I should have replaced the front sprocket washer and bolt as well for this exact reason. It did not make a lot of sense at the time either, especially since I run my chain very loose.
    #4
  5. GR0NK

    GR0NK Got some screws loose!

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    The spacer is the most expensive part at around $20 but is rarely needed. The seal, o-ring and bolt/washer kit will run you all of about $10 combined.


    Sean :bmwrider
    #5
  6. LukasM

    LukasM Long timer

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    The boys said it all pretty much.

    Only thing I can add is to use the 2-stroke O-ring as it's a tad thicker. 0770250020 from KTM if you are ordering other stuff anyway, or look for a 25,00mm X 2,00mm NBR 70 in the hardware store.
    #6
  7. Indy Unlimited

    Indy Unlimited Long timer

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    It is well known that aftermarket front sprockets are thinner and cause leaks on RFS motors. Just make sure you have a KTM front sprocket and then if it still leaks you can follow the advice of others above.
    #7
    rustytigwire likes this.
  8. GR0NK

    GR0NK Got some screws loose!

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    I did not know that. Thanks for the tip. :beer



    Sean :bmwrider
    #8
  9. firerigger

    firerigger Trauma waiting to happen

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    This is great info, just what I was hoping to hear. Now for the next part. Do you guys have the part numbers for these bits handy? My local KTM stealership is famous for screwing this kind of stuff up, and I want no doubts if I got to get the stuff from them or another supplier.
    #9
  10. GR0NK

    GR0NK Got some screws loose!

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    www.munnracing.com

    Click on "Microfiche" and then select year/model/engine/subassembly. (Transmission II 6-Gear 400-525 EXC, 525 MXC (EU))

    They will give you an online discount of 15% on the advertised prices.


    Sean :bmwrider
    #10
  11. LukasM

    LukasM Long timer

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    +1 on Munn. I have spent days looking at the microfiches of various models.

    Here are the numbers from my previous order:

    CS 14T 50033029014
    CS shaft seal 760324571
    Bolt+washer CS 59033034044
    O-Ring shaft 770020220
    or O-Ring shaft (2 Stroke 25x2) 770250020
    #11
  12. TriTi

    TriTi Tiger Adventurer

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    I just picked up a 2001 KTM EXC 400... I know these bikes are prone to be 'noisy'. I am just finishing up the water pump seal upgrade. I'm going to check the valves etc. while I'm putting it back together.

    I just noticed that my front counter sprocket has some side to side play in it. My next project on the bike was to tear into the clutch/gearbox as it is excessively noisy compared to a friend of mine's EXC 400 of the same year.

    I'm an aircraft mechanic and am not afraid to do anything on these bikes... but I would love input from you all who have 'been there and done that' as this is my first KTM and I am still very much learning the maintenance on this machine.
    #12
  13. RideFreak

    RideFreak Torque Junkie

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    Could be the primary nut, there's an alum nut in there that tends to loosen a little making for a noisy bottom end. It's a reverse thread so it doesn't loosen enough to come off. DJH on KTMTalk sells a steel replacement nut. The fix is to replace the woodruff key and retorque it with the new nut.
    #13
  14. Scott_PDX

    Scott_PDX Leisure Engineer

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    Bought an 04 450 EXC last Christmas and it was leaking as well. At first thought it was just the spring washer and sproket, but ended up doing it a second time to replace the other parts and do it right. It's an easy process, nothing to fear, I used a seal puller as well.

    They're fun bikes...my last weekend.

    [​IMG][/URL][/IMG]
    #14
  15. TriTi

    TriTi Tiger Adventurer

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    So... I got on KTMTalk but I pretty much can't do anything on that forum until I do a bunch of stuff to "get out of probation". Is there any EASY way to get in touch with DJH on KTMTalk so I can get the steel replacement nut?
    #15
  16. cjbiker

    cjbiker Nobody's Robot

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    Try this:

    http://www.djhcyclesport.com/contacts/
    #16
  17. TriTi

    TriTi Tiger Adventurer

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    #17
  18. meierfire

    meierfire n00b

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    Hey Guys,

    I had the same problem with my countershaft leaking oil when I rode the bike. (It did not leak when the bike was off.) It took me a few weeks to finally fix it.

    After many trials and errors I finally fixed it by replacing the CS O-Ring, CS seal, CS metal bushing, replaced aftermarket CS sprocket with OEM sprocket, CS washer and bolt. (All parts were OEM KTM parts.) I don't believe you need to replace all of these parts but it doesn't hurt if they are older or the original ones. They are not that expensive. (The most important to replace are the CS seal, metal bushing and OEM sprocket.)

    My theory is that the aftermarket sprocket was too loose on the countershaft due to its teeth being slightly smaller than the OEM sprocket teeth that hug the CS. This extra vibration over time weakened the bushing and seal causing space to develop between the rubber seal and the metal bushing. My bushing even had visible lines worn into it from where the seal was touching it.

    (I also think that a loose chain can provide too much vibration on your CS sprocket, leading to the same issue. So keep you chains at proper tension.)

    When you take the sprocket off and look closely where the CS seal meets the metal bushing, there should be no space. The seal should hug the bushing tight. If there is ANY space, this is where oil can come out.

    To remove the old CS seal, (these are usually stubborn) use a small allen wrench to pry it out by hooking the short end of the wrench under the metal part of the seal and the long part leveraged against the outside of the metal part of the seal.

    Make sure when you install the new CS seal, that you do not bend it in any way or tear the rubber seal. If you do, it will be compromised. Install the seal as gently as you can by tapping a blunt hammer or using a hammer and towel to soften the blow to the seal. When you install the new metal bushing, make sure you slide it gently inside the rubber seal so that the seal hugs the side of the metal bushing evenly. Do not let one part of the rubber piece bend under itself. The seal should be snug to the bushing. (This is the most important part.)

    I even , with my finger, gently pushed the rubber part of the seal inward toward the CS before I slid the bushing on to make sure that it was going to be snug against the bushing. If you do this, do NOT push hard or you could compromise the seal integrity.

    I hope this works for you! I was super frustrated with this leak for a long time and I promised that if I ever fixed it, I would post this on every forum that I previously visited.
    #18
  19. DualDawg

    DualDawg Been Lurking

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    Great info as usual. Anyone know the torque spec for the countershaft bolt on 2005 KTM 450exc ?
    #19
  20. davesupreme

    davesupreme grand poobah

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    i always hear this.... i mic'ed the cheapo one from RMATV and it was the same as the KTM sprocket.... and the splines fit good.... that's the only other one i've tried except stock....

    sprocket nut torque... 60nm @ 45ftlbs....
    #20