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  1. #1
    bowsniper's Avatar
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    Couplers and that funny sl rattling

    How many types of couplers are there for these skis?

    Do the domestics use a different coupler?

    What goes wrong with them?

    When should use lube them from experience? every ride?

    I hear theres a lightweight one and a metal one? could someone explin that?

    Does it really make a difference to go to a lighter one? acceleration wise?

    Does the length of the driveshaft matter when using one over the other?

    How reliable are they? I bet that has EVERYTHING to do with using the alignment tool.

    Anyone have one blow up or get torn apart while running?

    Thats a good start anyways.lol


    Now to the rattling noise.. when my slt is idling ...sometimes I hear something in the coupler or near that area rattling and jingling around like something loose. Any one else ever hear that mysterious rattling sound.? Kinda noisey! Definetly can hear it but when running fast, nothing but good rpm sounds.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Well, there is the bonded rubber coupler, which became stock circa late 1990's - not sure exactly when

    Then there is the solid metal coupler, which I think was stock on the 780 Fuji models, and later the Pro 785. This is considered the toughest Polaris coupler design, but you can have more vibration. Drive shaft alignment is important.

    On the very early Fuji engines, there was a heavy flywheel style coupler. There was/is a needle style grease fitting on these early couplers.

    The rubber bonded couplers work fairly well, and they do dampen vibration, but of course they cannot compensate for a mis-aligned drive shaft.

    The only way to lubricate a bonded rubber coupler is to remove the drive shaft, insert some grease, then slide the shaft back in. That means the jet pump has to come off, of course.

    Sometimes they do fail. A particularly messy example is shown here, although others have developed a hairline crack around the splined part, that can be hard to notice, yet will slip under power.
    When a rubber bonded drive shaft coupler goes bad

    Odd man out is the MSX coupler, which is a three piece design with a spider shaped large rubber dampener. It can handle a lot of power, but only fits the MSX hulls which have the MSX specific through-hull bearing carrier.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    The rattly sound is the slop in the impeller and drive shaft splines resonating with the engine power pulses at low RPM. Mostly noticeable on the trailer, it should be almost silent in the water at idle, and definitely not hear-able at any speed above idle in the water.

    If the splines at both ends of the drive shaft are freshly stuffed with grease, it rattles much less, until the grease starts to work itself out.

  4. #4
    bowsniper's Avatar
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    Quote Originally Posted by K447 View Post
    The rattly sound is the slop in the impeller and drive shaft splines resonating with the engine power pulses at low RPM. Mostly noticeable on the trailer, it should be almost silent in the water at idle, and definitely not hear-able at any speed above idle in the water.
    Ok thanks for the great description of everything. So this rattling is normal.. Maybe a spline check on the driveshaft is in order just to check it our along the reverse spinles in the actual coupler. I'll look for that long spline crack too while im in there. This is on the slt.

    Will a Pro make the same sound like that? with a metal coupler? or is that just common to the rubber ones?

    Yeah, when I hit the gas it stops(the sound) immediately. I didn't use an alignment tool so that may be exasperating the problem possibly.

    Does eveyones sound like that? or just a few? I'm just trying to pinpoint how I can stop it. If you cant , you cant.

  5. #5
    PolarisNut's Avatar
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    The solid couplers will always be somewhat noisy, even when in the water...You need to be sure the motor is aligned perfectly though, or you'll wear the splines out...and it will be excessively noisy.

  6. #6
    bowsniper's Avatar
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    I bet some grease where the splines go in would keep it a lot less nosiey.I know mine had about zero grease on them. I never checked it.

  7. #7
    Race, wreck, repeat delagem's Avatar
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    Jingly noise-check your driveshaft, the little rubber bumpstops may be missing.

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