FLT 1990 main drive gear vs. spacer

Discussion in 'Transmission' started by toyz, Jun 30, 2012.

  1. toyz

    toyz Member

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    Because of a shifting problem, related to broken shift pawl spring, I took the 1990 FLHS 1340 evo, 5 -speed transmission apart.

    When removing the front gear (belt drive), I noticed a (slight) wear pattern on the pully inside, right where it contacts the spacer. There is no way I can think of an explanation for this, as it indicates there has been rotation/movement between these two parts, despite the nut being extremely tight (as it should).

    I have searched across the forum, finding a lot about splines gone, belts rubbing, gears grinding into gearbox housing, but nothing matching my concerns.

    As I am getting ready to put it back together (it all fits, no interference), are there any suggestions from your end?

    Measurements: Spacer OL: 21.35mm, sprocket center: 13.1mm, sprocket splines extend mainshaft splines by about 1mm (enough to warrant clamping of components when tightening nut), and sprocket clears the gearbox, although marginally, less than 0.5mm my guess.

    Will try to attach some pics.
     

    Attached Files:

  2. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    It has been a wee while since i was last in that far on one of the bikes but as i remember the pulley goes on as far as the splines on the shaft allow and the spacer covers the space between the pulley and the quad seal and fits snugly in the main drive oil seal
    the tension applied by the large nut holds the pulley against the inner end of the splines on the shaft and the spacer just fills the space and is not held by the nut tension if it was the quad seal would collapse and twist
    So it could be that the spacer could get stuck on the main drive seal and get rubbed against by the pulley causing the wear
    replace the spacer, quad seal, main drive seal. pulley. lock plate and nut is the way i would go

    Brian
     
  3. toyz

    toyz Member

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    Thanks for your thoughts.

    Looked again and found that splines on shaft are about 22mm length, whereas pully has about 13mm of splines, of which max. 12.5mm are used, so that pully sticks out far enough for nut to clamp.
    In my opinion the spacer bottoms at the bearing inner race, capturing the quad seal between spacer chamfer and shaft, whereas the pully bottoms at the spacer, while the whole assembly is clamped by the nut, making it all rotate with the shaft. That is why I cannot imagine the wear on the pully where the spacer seats, as if they have been rotating on each other.

    The spacer seems to be of a harder steel than the pully, but shows no signs of ever having been hot; the wear could have been from a few rotations, but more likely not from running for periods of time is my guess.
    The spacer rotates freely and easy in the seal, wheras the shaft rotates correctly in its bearing without binding, also after re-assembling the gearbox, what I just did.
    .
    I am thinking my brains out to figure if it could have been caused by taking it apart, but while undoing the nut, everything on the shaft is locked by blocking the pully; and if shaft and pully do not turn, I cannot imagine a way that the spacer can turn.

    Feel like putting it all back together and take it from there. However, other opinions or suggestions will be appreciated.

    Regards, Ad
     
  4. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The pulley is made of softer material than the shaft and the spacer so that if things go wrong the pulley will will be damaged and the main parts will survive
    whenever i have been that far into that area i have replaced all the seals and the spacer as a matter of course
    If i were in your place i would just put it all back together but replace the seals large nut and locking device i would also replace the main shaft oil seal the one that is between the main drive and main shaft as it is a fairly exposed seal and they can fail after 10+ years of use

    Brian
     
  5. toyz

    toyz Member

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    Have put it all back together, using new seals where thought appropriate.
    Turned out to be a lot of work to replace a $3.00 spring in the gearbox, requiring also a fair bit of special tools.
    Anyway, it shifts well again; hope it also stays oil tight.
    Few more pics attached to encourage (or discourage) others facing the same issue.
    Brian, thanks for the input and suggestions.
     

    Attached Files:

  6. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    Glad to here that you are back on the road again
    If you see a couple of British registered evo bikes passing you next week could be me and wife give us a wave

    Brian
     
  7. Billige

    Billige Member

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    Could be that your lock ring for the nut ground down to nothing and was spread across America like mine. At least I think that is it. I took my clutch pack out and just a nut there .. I did find in the dust a bolt head with maybe an 1/8" cap screw. there is no bolts on the drive pulley. mine has 3 threaded holes. I can only assume I need this locker. any help!
     
  8. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    For the pulley nut the lock plate was introduced in 1992 prior to that a single bolt was used in one of the three possible locations and is fitted where it best prevents the pulley nut from coming loose
    If the lock bolt is damaged it may be that the pulley nut has come loose a wee bit it may be a good idea to replace the nut and fit a lock bolt
    A new pulley nut should come with the relevant Loctite (262) on the threads ensure the main drive threads are fully clean and torque to 150 lbs-ft then check for lock bolt position you can tighten up to 160 lbs-ft to get the lock bolt in correct position
    The pulley nut is on a reverse thread so a bi-directional torque wrench is required as most torque wrenches will ratchet in both directions but only count torque in normal direction on bi-directional torque wrenches the square drive slips through the torque wrench to allow it to count the force in the other direction

    Brian
     
  9. Billige

    Billige Member

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    You were zackly right! Only one cap screw holds main drive nut. Thank you for increase torque note: 157 is what I ended up with.
     
  10. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    It is good to see that you are getting it sorted just watch when you put the inner primary on that you seal the 4 bolts to the gearbox some sealant on the lock washers and the bolt heads should be sufficient as it is a pest to strip it all again when primary oil starts leaking

    Brian