Motor mount?

[glider]

Very possible that the mount could be collapsed and what you feel is the metal part bottoming out.

Take a look here...

Harley Davidson Community

Harley Davidson Community

 

[R_W_B]

I am getting a strange vibration on my '97 FXD.When I hit bumps at highway speeds,and I dont mean anything big,just going over the "seams" that cross the lane every 30 feet or so,it feels like its bottoming out.Nothing real loud or hard,just a kind of scraping sensation thru the foot pegs.When I slow down and downshift to first and kind of idle to a stop I get a chattering in the engine.Could this be a motor mount problem?Any way I can test to be sure?Thanks in advance for any suggestions.

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.

 

[glider]

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.

 

[R_W_B]

I could pull the front one over the winter while the bike is idle.If it looks bad I'll get at the bottom or rear as well.I think I remember reading somewhere that there is an improved unit for this bike, have any info on that?

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.

 

[wilks3]

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!!!
wilks3
:USA

 

[R_W_B]

"I shimmed the preload out of mine when I replaced the front".Could you explain this,and why it is better to shim it.Thanks.

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.

 

[R_W_B]

I never said mine was "shimmed",I dont know that it is.It is original,only 13,500 miles but still almost 15 yrs old.I havent checked those torques,but I guess I'll do that first.Thanks.

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.