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V65 clutch issue

Discussion in 'Small Block' started by Ivan_J, Jun 9, 2019.

  1. Ivan_J

    Ivan_J Just got it firing!

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    I seached for similar problem, but not find much information.

    I'm building a custom bike from an old V65TT.
    I bought the donor cheap and not running.
    Dismantled engine only to find out the timing chain spring is broken. The engine is in good condition.
    The clutch friction plate was shot so I change it with a friction plate from a car - probably some old Fiat ot Renault. The only differece is the center hub length so I cut it down.
    Now the bike is almost ready. I started it and found there is a big rpm drop when I pull clutch in idle. There is noticeable rpm drop with clutch pull even at higher rpm. And the clutch drags.
    Measured crankshaft thrust play - 0.15mm (service manual says up to 0.45).
    The thrust bearing is in good condition. The problem persists with any clutch adujstment - as per manual, with and without free play.
    I'm out of ideas.
     
    Last edited: Jun 9, 2019
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Two things can cause the clutch drag. Improper adjustment of the clutch cable (too much free play) and arm at the gearbox not at 90 degrees to the clutch push rod or the clutch plate is too thick.
     
  3. Ivan_J

    Ivan_J Just got it firing!

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    Today I drop the engine to check if there are any visible clutch issues.
    Nothing. Flywheel have rust pits. As the rust can cause dragging, can not cause rpm drop.

    Friction plate(is new) is 7.5mm thick and is straigth, push rod is 227mm. Clutch freeplay is adjusted as it should - 2mm at lever.
    Reconnected the engine and gearbox and started the bike. Again rpm drops.
    I think to finish the bike and drive it a bit. It is possible the clutch breaks in.
     
    Last edited: Jun 10, 2019
  4. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    I don't know the Guzzi spec for a new plate. Since you used an automotive plate it may be thicker. Also did you get both side of the clutch hub area? If too wide that might be an issue.
     
  5. Ivan_J

    Ivan_J Just got it firing!

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    Guzzi specs new plate at 8mm, worn limit 6.5mm.
    The hub is longer transmission side only, engine side is shorter.
    In V7-III engine manual I found the following pictures
    [​IMG]
    As I can see thrusts can't be mounted wrong way but as I can't remember for sure how I installed them, I'm considering dismantling the engine to check as this can lead to rapid crankshaft wear. And can cause rpm drop but not clutch drag.
    Can I lift the crankshaft without removing top ends? Just removing timing chain, oil pan and splitting the cases?
     
  6. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    You may also have to disconnect the connecting rods to lift the crankshaft.
     
  7. Ivan_J

    Ivan_J Just got it firing!

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    I'm already remounting the engine. There is nothing wrong inside except worn main journals that I know of previously. They are just off the limits. When I build that engine I don't have access to the V7III engine which states limits, but V65 engine gives only factory clearances.
    V7 manual give limits of 0.08mm for front and 0.09mm for rear bearing. I measured 0.10mm.
    Today i also found there are oversize main bearings for some V65 models and for V7, not for TT. Old V65 manual state there are no oversize bearing shells and crankshafts are not grindable to undersize. Unfortunately V65tt and newer V65 crankshafts have different part numbers.
    I can order oversize shells but I don't know if my crankshaft can be grinded to undersize and work well after that. So I think of leaving it as is.
     
  8. Ivan_J

    Ivan_J Just got it firing!

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    I've changed the clutch pressure plate and the problem is solved. No clutch drag, no rpm drop. And no problem with increased main bearings clearances - oil pressure warning lamp stays off even with hot oil and lowest possible idle. The oil is 10W60 Repsol.
    Thanks for the input.
     

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