Ever wonder if changing some or all of the engine mounts to utilize polyurethane would benefit a softail evo?
What if someone machine some polyurethane down to mount the top mount horizontally and vertically while still keeping some of its rigidty... I'll let you know in a week or so if it does anything to reduce some of the highway speed vibration....

 

Polyurethane mounts will transmit more vibration over a rubber mount. They are stiffer in design. An example is in my Mustang. It has poly mounts and you can tell the difference over the rubber mounts.

 

I have chosen a medium durometer polyurethane, which is about the same or just a little firmer than the rubber used on the Dyna mounts. From the Prothane website:
Polyurethane is a term used to describe a wide ranging family of elastomers (any compound exhibiting the characteristics of natural rubber; stretchy and elastic.). Poly meaning "many" and "urethane" the classification of the chemical structure. Polyurethane or urethane for short, is used as a solid cast material (bushings). Polyurethane can be as soft as a rubber band or as hard as plastic.

 

I'm not trying to sway you from doing it. Poly mounts last longer and hold up much better than rubber mounts. They also are much stronger. I still feel that you will feel more vibrations using one over a rubber mount. Do the swap and let us know the results. Good luck.

 

He is using this material on a Softail, which has a rigid mounted motor. He is not replacing rubber mounts, he is just trying to add some cushion, so any gain he gets will be an improvement. That is my understanding anyway.

Regards,

Bill

 

Bingo Bill! My fault, I assumed that was understood... I will have to keep an eye on the mounts to make sure they don't deteroirate. I did replace the bushing in my handle bar mounts as the old ones were too mushy... so I may have canceled out the effect...

 

Makes sense to me now.

 

I'd be interested to know how it works. The EVO's had a lot of vibration. I got rid of an 87 Softail because of it.

 

I will wait to see if it helps,

My deuce has a little to much vibration at 90 plus.

Maybe i should just slow down, nah i will wait to see if they help with the vibration.

David

 

Before y'all get carried away with this, there's a little something to consider. The Softail's engine is rigid-mounted to the frame at 6 points; 2 front, 2 rear, and 2-to-1 point on the heads-to-frame. It is also rigidly mounted to the inner primary, which is rigidly mounted to the transmission, which is rigidly mounted to the frame. Effectively the engine, primary, and transmission become one unit, but connected together only on the left side. If you design some flexible engine mounts, the engine will vibrate and move, but the primary and transmission won't. You'll break the inner primary at a minimum. I've seen them break when someone assembled a bike and slightly misaligned them.

If you'll look at the rubber mounted Dyna or Barge series, you'll notice the transmission is solidly coupled to the engine on both sides, not just the primary side. This allows the engine/tranny to function as one unit, with no stresses between them. Even if you rubber mount a Softail motor and transmission, they are still only coupled on the primary side. They will not move as a unit, and the stresses will still screw up the primary, at a minimum. You'd have to design something to couple both sides of the tranny to the engine.

Of course, anything is possible, but sometimes it ain't practical, or cost-effective.