1. Husqvarna Motorcycles Made In Sweden - About 1988 and older

Tapered Shaft Sprocket Woes

Discussion in 'Vintage/Left Kickers' started by Crashaholic, Oct 20, 2018.

  1. Crashaholic Husqvarna
    Pro Class

    Location:
    Antelope Valley, CA.
    Husqvarna Motorcycle:
    73 450WR 6spd motor in a 75 MK frame
    I acquired a 73 250 motor that had a broken counter shaft sprocket. What a crappy sight to see knowing it may not come off without damaging the shaft. Tapered shaft sprocket removal has been a real bugger for some people so I thought I would share my attempt at removing this busted up sprocket.
    20181006_111334 B.jpg


    Made a shield to protect the surrounding area.
    20181006_111936 B.jpg


    Because there wasn't enough of the sprocket left to get a hold of with the Husky puller arms I used two bolts in their place and the mig welder to secure them to the sprocket.

    I torqued the puller to 40 ft. lbs, HVA recommends 30 ft. lbs. but I thought it was too conservative after feeling the little force it took to move the wrench. I then applied heat using an oxy acetylene torch for about five mins with no results. Don't worry I had my sheet metal shield in place for the torch even though its not in the photo.
    20181006_115644 B.jpg


    After staring at this thing for 30 mins I thought if I cutoff some of the sprocket, a little on each side, maybe it would expand faster than the shaft and allow the puller to do its job. I used an angle grinder with a cutoff wheel to hack off what I could without damaging the shaft. Looks like a mess at this point.

    20181006_131205 B.jpg
    DeathFromAbove likes this.
  2. Crashaholic Husqvarna
    Pro Class

    Location:
    Antelope Valley, CA.
    Husqvarna Motorcycle:
    73 450WR 6spd motor in a 75 MK frame
    With the same amount of torque I lit up the torch and within 15 seconds of applying the heat the puller and sprocket jumped off the shaft. I don't know but maybe the vibration from the grinder had a role in loosening the sprocket but none the less it was a pleasing moment especially since the shaft came out unscathed.
    20181006_131410 B.jpg




    Seal is toast.

    20181006_132524 B.jpg



    You can see theres not much sprocket on either side. Did this helps speed up expansion before the shaft got hot or did the grinder vibrate the crap out of it? Heck if I know.
    20181006_132605 B.jpg
    jack topper and markt2 like this.
  3. Crashaholic Husqvarna
    Pro Class

    Location:
    Antelope Valley, CA.
    Husqvarna Motorcycle:
    73 450WR 6spd motor in a 75 MK frame
    Obviously this would of been much more difficult if the motor would have been in the frame and removing it from the frame would have been a lot of additional work. Even so I think this could be done while the motor is in the frame as long as necessary steps are taken to insure something doesn't catch fire.

    In the early 70's HVA put out a Service Bulletin warning dealers about a run of bad sprockets that would slide onto the shaft farther than normal making them difficult to remove. I think that applying to much torque could also drive a sprocket to far onto the shaft causing a similar problem.

    1973 Counter Shaft Service Bulletin Pg 1.png




    1973 Counter Shaft Service Bulletin Pg 2.png
    Krudd likes this.
  4. jimspac Husqvarna
    Pro Class

    Location:
    Connecticut
    Husqvarna Motorcycle:
    82 250WR, 82 430WR, 84 250WR, 85 400
    Other Motorcycles:
    86 400WR, 82 Montesa Cota 349
    If you split the cases , I know of a few that have replaced the tapered countershafts with splined.
  5. motorick Husqvarna
    AA Class

    Location:
    Jacksonville, OR
    Husqvarna Motorcycle:
    1974 400 CR, 1987 250 XC
    Other Motorcycles:
    1973 Norton Commando
    Nice job! I wound up cutting the sprocket off, but nicked the shaft. Fortunately I found a 250 5 speed one on ebay so I'll be converting to splined when I rebuild it.
    Crashaholic likes this.
  6. Crashaholic Husqvarna
    Pro Class

    Location:
    Antelope Valley, CA.
    Husqvarna Motorcycle:
    73 450WR 6spd motor in a 75 MK frame
    And miss all this fun everytime I want to change a sprocket? :) Actually I have a couple of later model six speeds and I was comparing the spline shafts from 74 and 76 and it looks like either will work. Definitely a must do when the cases are apart.
  7. husqyman Husqvarna
    AA Class

    Location:
    S.E Kent UK
    Husqvarna Motorcycle:
    1988 XC430, 1987 250WR.
    Other Motorcycles:
    Triumph Tiger 955i
    Nice Job. Thanks for sharing, While not on any of my bikes, tips like help give inspiration for similar problems that other's have.
    Kev W