Originally Posted by grbrown

That is engineering speak, in which "uniplanar vibrations" simply means an engine unit which naturally vibrates up and down, which our Harleys do, as will your diesel engine. The "uniplanar isolation system" is what I have already described above, in which the "motor" (meaning the engine/transmission) is mounted at three points, with stabilizers to control how it can vibrate in only the vertical plane.

Originally Posted by grbrown

I spent a lot of time many years ago studying Harley's US patents relating to their rubber mount bikes, which Erik Buell had a major hand in. So my comments here are based on my understanding of the original concept. I've had to retrace my steps and study them again, to refresh my memory! For reference simply do an internet search for "US patent 4776423A" and "US patent 6,213,240B1", but get a long drink first!

In the first of those Buell says in the ABSTRACT:

"A motorcycle frame design featuring a uniplanar isolation system. This is a system for vehicles which have motors that have basically uniplanar vibrations. It provides mounting means which allow the motor to have vertical and longitudinal movement, but prevent lateral motion of the motor and rear suspension unit with respect to the main frame."

That is engineering speak, in which "uniplanar vibrations" simply means an engine unit which naturally vibrates up and down, which our Harleys do, as will your diesel engine. The "uniplanar isolation system" is what I have already described above, in which the "motor" (meaning the engine/transmission) is mounted at three points, with stabilizers to control how it can vibrate in only the vertical plane.

To answer your question about adding an extra support at B, I believe that is inviting problems. The original rubber system of your bike had the engine and transmission fastened together and I really do suggest that is what you do with your bike. Only that way can you maintain the concept of the three point mounting system and the benefits it gives, bearing in mind that you also have the bulk and weight of the swingarm and rear wheel hanging off the back of the transmission.

Originally Posted by Finmad

Alright, I am going to give it a shot without mounting at B. What's the worst that can happen?? I break the transmission mounting surface. I will build the top mount strong enough to "catch" the motor if the junction between the engine and trans fails, so I don't drop a $2,000 motor on the ground at speed. Lets put our faith in engineering.

Originally Posted by Max Headflow

Also you will need to stabilize the mounting so that any forces perpendicular to that plane are transmitted to the frame. The main reason for this stems from the rear wheel needing stabilization in that plane so that the front and rear wheels maintain proper alignment. I too have looked at Buell's patent along with the Norton patent and a few others.