Stuck front sprocket F800GS '16

Discussion in 'Parallel Universe' started by Scarfall, Feb 18, 2020.

  1. Scarfall

    Scarfall Adventurer

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    Hey all,

    Bought this bike at 6k miles so sprocket is probably stock. I want to change to a 15T but I can't seem to be able to slide it out. It seems like the rust has solidified between the spindle and sprocket. I have tried giving it a lot of whacking with a hammer. I went out to get a blowtorch but no luck. I think my next step might be going to get a bearing puller. Or a mechanic.

    Attached Files:

    #1
  2. JRWooden

    JRWooden Homeless motorcycle vagabond ... and ... loving it

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    blow torch could potentially kill the oil seal

    There's not a lot of clearance behind the sprocket so the jaws on some of the pullers might not fit (cast iron fingers being too fat)
    A buddy of mine had a puller that looked something like this and it (barely) did the job, but it did the job ... :drink

    https://www.ebay.com/itm/Powerbuilt-4-2-Jaw-Light-Duty-Gear-Puller-640961/281307586800

    Hell ... for $8 bucks I'm going to buy one right now just to throw in the tool box....

    Weird it would seize with only 6K miles ... paint the new one with never-seize or your choice in that product category.
    #2
  3. bmwroadsterca

    bmwroadsterca RadioFlyer

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    Penetrating oil.
    #3
  4. shuswap1

    shuswap1 Long timer

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    Penetrating oil for a couple days then use a puller. Someone may have locktited it or it may be a little corrosion helping the parts get too familiar with one another.
    #4
    malloy likes this.
  5. Scarfall

    Scarfall Adventurer

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    It remains stuck! The gear puller didn't work, I've tightened it to 100nmm and it didn't move a nanometer.
    #5
  6. BMW-K

    BMW-K F800GS FTW!

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    Ok, so the good news is you got the nut off and the locking washer, right? The bad news is that the sprocket won’t pull off the spline. Do I have that right?

    Looking at the pic, I’d bet there’s some real grit stuck in the teeth of the splines that cannot compress going outward.

    Me personally, I’d take a small hammer and start tapping all the way around the edges of the sprocket: north to south, east to west. Start on the outer edges and make a few raps, then move to the inside and tap on the inside (*might be useful to use a large socket that extends over the splines).

    Take your time. LOTS of smaller and light-medium taps. NOTHING BIG. Just keep taping - north to south, east to west, north to south, etc.

    Basically, tap the sprocket back ON...and spray the sprocket with lots of penetrating oil. Lots of little bursts as it were. Tap tap tap...spray...tap tap tap...spray.

    This might take 30 minutes. Be patient. Get the exit splines as clean as you can before trying to pull it off again.

    That’s my thought anyways.

    PS: looking at that pic again...am I missing something or is the chain still on the bike? From that pic, it sure looks like you have sprocket teeth jammed up against the chain which is jammed up against the frame. That’s not going to budge until the chain is moved out of the way - like, replacing it.
    #6
    Benduro likes this.
  7. erburtt

    erburtt Adventurer

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    I might add, that when you have the gear puller tensioned up, it would be helpful to tap around the sprocket in the same manor as described above. I'd use a ball peen hammer and only high the sprocket, just trying to shock it loose. Would achieve more than just pulling on it with the gear puller. Similar to taking a ball joint out of a car if you've ever done that.
    #7
  8. bmwroadsterca

    bmwroadsterca RadioFlyer

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    I think I would put one of those thin cutoff discs into an angle grider and cut a radial slit in the sprocket almost to the splines then use a chisel in the slit to break/split the remaining material and it would come off for sure.
    #8
    JRWooden and Benduro like this.
  9. bmwroadsterca

    bmwroadsterca RadioFlyer

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    @Scarfall so what did you do? Is the sprocket off?
    #9
  10. flei

    flei cycletherapist

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    There was a thread posted a while back with the same issue. FWIW, the owner had to use a cut-off wheel to cut the sprocket to get it off.
    #10
  11. malloy

    malloy Long timer Super Supporter

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    Any progress here?
    #11
  12. Scarfall

    Scarfall Adventurer

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    No luck so far. I've been pretty busy with work but will drop the bike off at an independent BMW mechanic on Monday, he said he'd order the parts after seeing the bike.
    #12