Replacing Front Motor Mount / Isolator?
Thread Starter
|
Advanced
Joined: Mar 2007
Posts: 74
Likes: 1
Replacing Front Motor Mount / Isolator?
Going to be replacing my front motor mount / isolator on my 06' FXDWGI, which per the service manual seems pretty simple.
Questions: Do I need to go throught the whole chassis / engine alignment procedure after I change the mount / isolator? Service manual does say to do it after changing the mount / isolator, but thought I should ask.
Questions: Do I need to go throught the whole chassis / engine alignment procedure after I change the mount / isolator? Service manual does say to do it after changing the mount / isolator, but thought I should ask.
Stellar HDF Member
Joined: Mar 2006
Posts: 3,124
Likes: 255
From: From Long Island, now in So. Cal
I would do the chassis / engine alignment procedure, as well as shimming the mount (see below).
Having the engine mount preloaded from the factory is most likely the cause of engine mount failures. When I removed my vapor canister my frame mount pulled forward and the engine mount also pulled away into a stress free condition. I had a jack under the engine so that I could screw the bolts in by hand with no resistance which gave me a 3/8" gap that I shimmed with washers. Then I came across the below post and it seems to be a common problem on rubber mounted bikes.
FXD Vibration Problem Cured - $10 Materials
Sorry for the long post, but I have cured my Dyna's vibration problem for about $10 in materials and I thought others might benefit from my approach.
I have a 2005 FXDI with a HD 95 inch Stage I kit.
Like some others on the Forum, my bike had, what I consider, excessive engine vibration transmitted to the handlebar, foot pegs, and seat. The vibration was especially evident below 3000 rpm. At idle, the handlebars jumped around excessively.
I followed the Service Manual procedure for vehicle alignment in an attempt to reduce the vibration. Alignment includes loosening (but NOT removing) ALL the motor mount attachment bolts, and then running the motor for 5 seconds during which allow the mounts to align themselves to the frame. The motor mount attachment bolts are then re-torqued to spec. The procedure helped a little, but did not cure the problem. I also looked at other changes that might address the vibration problem such as a Bar Snake, different length handlebars, handlebar mount bushings, etc. All these are Band-Aids on the fundamental problem of too much vibration.
A few weeks later I was thinking about the motor mounts and the alignment procedure and was struck by the cause/cure of the vibration problem. Any elastic motor mount, like the Dyna's, has a limit to how much vibration it can absorb. Engine movement in excess of this limit is transmitted through the frame to the handlebars, foot pegs, seat, etc as vibration.
What struck me was that when I did the alignment procedure and the mounting bolts were LOOSE, there was a gap between the mount and the frame. Tightening the mounting bolts caused my front motor mount to be PULLED forward to the frame as the mounting bolts were tightened. I noticed that when the mounting bolts were torqued, the frame was also deflected somewhat.
THE ELASTIC TRAVEL OF MY MOTOR MOUNTS WAS LARGELY USED UP JUST BY BOLTING THE MOTOR MOUNT TO THE FRAME.
Any movement of the motor would not be absorbed by the mount as the elasticity of the mount is already used up before the motor is even started. Hence any engine movement is transmitted to the frame and is felt as a vibration. This would also explain premature failure of Dyna motor mounts as they are under stress to begin with.
My solution was to shim the gap between the UNSTRESSED front motor mount and the frame. THE ENTIRE INHERENT ELASTICITY OF THE MOUNTS IS NOW AVAILABLE TO ABSORB ENGINE MOTION. MY VIBRATION PROBLEM WAS GONE!
EDIT ---------
Try this site for photos: http://spotks.blogspot.com/
EDIT --------
Picture shows the gap between the unstressed front motor mount and the frame of my bike as it is almost 0.2 inches. The solution is to shim this gap.
Picture shows my test where I used washers as shims to test my theory. Result - excessive vibration is GONE. The bike is very smooth and the handlebars don't jump around at idle.
Picture shows the final result. I cut some brass shim stock to fit and used longer bolts to accommodate the shims thickness.
Picture shows a scissors jack and block of wood I used to hold the engine up when I had the mounting bolts removed. I had my wife steady the bike and hold it level while I worked on the mount.
Sorry for the long post, but I have cured my Dyna's vibration problem for about $10 in materials and I thought others might benefit from my approach.
I have a 2005 FXDI with a HD 95 inch Stage I kit.
Like some others on the Forum, my bike had, what I consider, excessive engine vibration transmitted to the handlebar, foot pegs, and seat. The vibration was especially evident below 3000 rpm. At idle, the handlebars jumped around excessively.
I followed the Service Manual procedure for vehicle alignment in an attempt to reduce the vibration. Alignment includes loosening (but NOT removing) ALL the motor mount attachment bolts, and then running the motor for 5 seconds during which allow the mounts to align themselves to the frame. The motor mount attachment bolts are then re-torqued to spec. The procedure helped a little, but did not cure the problem. I also looked at other changes that might address the vibration problem such as a Bar Snake, different length handlebars, handlebar mount bushings, etc. All these are Band-Aids on the fundamental problem of too much vibration.
A few weeks later I was thinking about the motor mounts and the alignment procedure and was struck by the cause/cure of the vibration problem. Any elastic motor mount, like the Dyna's, has a limit to how much vibration it can absorb. Engine movement in excess of this limit is transmitted through the frame to the handlebars, foot pegs, seat, etc as vibration.
What struck me was that when I did the alignment procedure and the mounting bolts were LOOSE, there was a gap between the mount and the frame. Tightening the mounting bolts caused my front motor mount to be PULLED forward to the frame as the mounting bolts were tightened. I noticed that when the mounting bolts were torqued, the frame was also deflected somewhat.
THE ELASTIC TRAVEL OF MY MOTOR MOUNTS WAS LARGELY USED UP JUST BY BOLTING THE MOTOR MOUNT TO THE FRAME.
Any movement of the motor would not be absorbed by the mount as the elasticity of the mount is already used up before the motor is even started. Hence any engine movement is transmitted to the frame and is felt as a vibration. This would also explain premature failure of Dyna motor mounts as they are under stress to begin with.
My solution was to shim the gap between the UNSTRESSED front motor mount and the frame. THE ENTIRE INHERENT ELASTICITY OF THE MOUNTS IS NOW AVAILABLE TO ABSORB ENGINE MOTION. MY VIBRATION PROBLEM WAS GONE!
EDIT ---------
Try this site for photos: http://spotks.blogspot.com/
EDIT --------
Picture shows the gap between the unstressed front motor mount and the frame of my bike as it is almost 0.2 inches. The solution is to shim this gap.
Picture shows my test where I used washers as shims to test my theory. Result - excessive vibration is GONE. The bike is very smooth and the handlebars don't jump around at idle.
Picture shows the final result. I cut some brass shim stock to fit and used longer bolts to accommodate the shims thickness.
Picture shows a scissors jack and block of wood I used to hold the engine up when I had the mounting bolts removed. I had my wife steady the bike and hold it level while I worked on the mount.
Tourer
Joined: Feb 2011
Posts: 351
Likes: 2
Why are you replacing the mount?
The way I replace the front is to:
Have friend sit on it and hold the bike straight upright, someone who is also close in weight.
Loosen the all bolts that hold the mount to the frame and to the case.
Jack up the the engine just enough to take the weight off of the frame bolts and remove all bolts.
R+R the mount leaving the case mount bolts slightly loose and jacking the engine up to where the the frame mount holes are aligned with the mount threaded holes so you can start the bolts by hand.
If there is a significant gap, more than 3/32 (approx 1 washer), then I would recommend using some flat washers to fill that gap and also using a bolt that equals the amount of shim in length so you don't strip the threads in the mount. If you need more than just a couple three washers, then I would look for other issues.
(If you feel the need to shim it and you need to go get the washers and bolts, then tighten everything down while the bike is upright, go get your supplies and then start over.)
While keeping the bike upright lightly snug the frame bolts and then the case bolts, while sitting on it, lower the jack and start the engine for a few seconds and shut it off and torque the frame bolts and then the case bolts to spec.
Should be good to go without any alignment, your call, it is tedious and usually comes out in spec.
My
The way I replace the front is to:
Have friend sit on it and hold the bike straight upright, someone who is also close in weight.
Loosen the all bolts that hold the mount to the frame and to the case.
Jack up the the engine just enough to take the weight off of the frame bolts and remove all bolts.
R+R the mount leaving the case mount bolts slightly loose and jacking the engine up to where the the frame mount holes are aligned with the mount threaded holes so you can start the bolts by hand.
If there is a significant gap, more than 3/32 (approx 1 washer), then I would recommend using some flat washers to fill that gap and also using a bolt that equals the amount of shim in length so you don't strip the threads in the mount. If you need more than just a couple three washers, then I would look for other issues.
(If you feel the need to shim it and you need to go get the washers and bolts, then tighten everything down while the bike is upright, go get your supplies and then start over.)
While keeping the bike upright lightly snug the frame bolts and then the case bolts, while sitting on it, lower the jack and start the engine for a few seconds and shut it off and torque the frame bolts and then the case bolts to spec.
Should be good to go without any alignment, your call, it is tedious and usually comes out in spec.
My
Road Captain
Joined: Oct 2010
Posts: 683
Likes: 3
From: Florida
I've done this and the shim. The previous posts are good advice. I think I would at least check the vertical alignment and see if the new mount sits the same way as the old one. If it's off then do the vertical.
Ther rear wheel alignment (non vertical speaking) should not be affected since it's tied to the swing arm.
Pay attention to which side of the bike your inclinometer needle (or digital )reading is facing. They both need to face the same way in the end or at least very close to it.
Ther rear wheel alignment (non vertical speaking) should not be affected since it's tied to the swing arm.
Pay attention to which side of the bike your inclinometer needle (or digital )reading is facing. They both need to face the same way in the end or at least very close to it.
Thread
Thread Starter
Forum
Replies
Last Post
