Motor mount?

Discussion in 'Dyna Models' started by glider, Oct 10, 2011.

  1. glider

    glider Veteran Member

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  2. R_W_B

    R_W_B Senior Member

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    I had the front mount go bad on my 2007 FXDB. I felt quite a bit of vibration in the pegs above 50 mph. Don't recall any bottoming out feeling though.

    Only way to really check them is to pull them out and look at them. There would some deformed looking stretching or loosness to a failed unit.
     
  3. glider

    glider Veteran Member

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    The links were meant to show the areas that go bad in the mounts mostly in baggers. Yours are a bit different more like this one.

    [​IMG]
     
  4. R_W_B

    R_W_B Senior Member

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    You could check with your dealer on any improvement. I know the newer (09 and above I think) are a stiffer mount. Some say they vibrate more. In any case yours look more like my 07 mounts.

    Front mount (my 2007 #47583-90b is same # as yours)
    Your 97 FXD at,
    47583-90B | Zanotti Motor Co. Inc. $73 bucks plus shipping

    Rear mount (my 2007 #47568-99 is different # than yours)
    your 97 FXD at,
    47564-90B | Zanotti Motor Co. Inc. $69 bucks plus shipping

    your 97 FXD at,
    Front mount
    Front Motor Mount Isolator for 1991-1998 Harley FXD Dyna Super Glide - www.debrix.com $96 bucks plus shipping

    When you pull the front mount look at it from all angles. The front is usually the one to suffer from the preload stretch. If you replace them both it's easier to do them one at a time to hold the engine in place. You need a sissor jack (or a hydraulic that won't sag) in any case, but it might be kinda tricky holding the engine stable with both of um out at the same time.

    I shimmed the preload out of mine when I replaced the front. If you do that and shim it much at all you will need longer grade 8 bolts for sufficient penetration. But don't get them too long, the mount will only accept 1-1/8" of thread depth.

    In any case here's a pic of my old and my new. Notice the old one is stretched forward, it's the one on the right. The other pic is of putting my shim washers in.
     

    Attached Files:

  5. wilks3

    wilks3 Junior Member

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    If you shim the mount you are not stretching it while bolting to frame. Check out the self help section, I believe there are pics. Pics are good!!! :D
    wilks3
    :USA
     
  6. R_W_B

    R_W_B Senior Member

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    It's like Wilks said, basically the OEM design theory was to stretch the motor in rubber and aleviate vibration. However the mounts tend to become deformed prematurely from too much stretch. It's been a common modification for some years by some to shim out this gap on the front mount thereby giving a more solid tie to the frame. Most say (including me) that there is less vibration (mine was noticable only above 50 mph). Others say they could tell no difference.

    I have a question, how old is this 'shimmed' mount that you are wondering if it's bad ?

    Have you checked the torque on your front and rear mounts ?

    Also check the torque on your swingarm mount bolts.
     
  7. R_W_B

    R_W_B Senior Member

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    Oh ok, sorry didn't notice the quotation marks. Anyhoo I would check all those torques and examine the mount if you pull it off. If you buy a new mount it will probably shim out over a 1/4 of an inch (bout 4 washers). I used Stainless washers and grade 8 hex head bolts from Fastenal or Ace. Just make sure the bare shank does not get into the mount threads and the threaded shanked section penetrates the mount at least 3/4 of an inch and not more than 1-1/8 inch.

    I say bare shank because the only fully threaded shank grade 8, I could find besides the hex heads were black iron and would rust. The hex heads are plated with brass colored coating (no idea what it is) but it is more rust resistant. I keep silicone sprayed on mine. I would not use Stainless bolts as their grade ratings are weaker and ambigous.

    BTW I replaced my front mount at 14,000 miles.