Thanks brother. I have been playing with cars and bikes since I was 13. People ask me "Where did you learn how to do that stuff?" my answer is "You don't have to know how to do something before you try to do it. That is part of the fun of learning something new". just take your time, use youtube as much as possible, get on forums (like this one) and ask questions, and just be logical. And if the whole project fails, then you learned what not to do next time. Growth comes from failure, if you have nothing but success you will learn little.

 

I would love to see it running!!

 

No tech to add but I really like the idea and build.

 

Let's start with the original engine/trans unit. I can't find a decent image of an Evo with its trans, so we'll have to make do with this M8 and use a little imagination. We're interested in the blue features, at A, B, C and D.

• A provides the rear mounting point for the trans in the frame, as well as the swingarm pivot point.
• B is where the engine and transmission are bolted together. On your Evo this looks different and is not as robust, but the two are directly attached to each other.
• C provides the front mounting point of the engine.
• D is the top engine mount.

Remember the swingarm is attached to the trans and the rear wheel is also a part of this substantial assembly. Together they probably represent around half the total weight of the bike, all supported at A and C. So with your 'new' bike you need IMHO to replicate that structure, to retain the rubber mount concept.

If you separate your engine and transmission from each other you lose the structural integrity they provide. Also while riding and cornering, the various loads are going to be transmitted from the rear wheel into the structure of the engine/trans, which is why the triangle made up of A, B and D, supported by the junction at B, are so important to the underlying concept of the H-D rubber mount system.

My concern is that if you don't join them, you will have other problems! Your engine plainly has a LOT of torque, not quite as much as my S&S engine, but at much lower engine revs. The M8 engine/trans unit in the pic below has a much more robust junction between crankcase and transmission casing, to overcome relatively low stiffness with our Evo design. Your mounting plates will probably need to be darned strong!

I'm happy to discuss further, from my safe viewing point across the Atlantic!

 

Check with these HD engineers . They finished one when they retired. Your's looks interesting .

 

So I can bolt the trans to the motor. I have the trans to swing arm and the front motor mount. My difference will be swapping the top mount for one under the junction of the trans and engine at point b.

 

From the link I posted at #7 above:

• The rear rubber mounts at A serve several purposes. The ends of the swingarm axle are fastened to those mounts, which are retained in the frame by the passenger footboard mountings. They support a large part of the weight of the bike; locate the engine/trans in the frame, both laterally, vertically and fore and aft; also allow it to rotate up and down, or pitch.
• The front rubber mount at C supports the front of the engine/trans and allows it the freedom to move up and down, rotating on the rear mounts. It is laterally supported by a stabilizer link, which prevents the unit from moving sideways at that point, or yaw.
• The top support at D is a simple stabilizer link, which also has several purposes. It doesn’t bear any weight, but allows the engine/trans to rock up and down, also back and forth, while preventing it from moving sideways, or roll.

It is crucial that D is above the engine, to create a strong triangle along with A and C. If you place it under B it will not prevent roll of the engine/trans in the frame. Your design will not be kinematically sound!

 

Good point, I can throw one up there. man I love this discussion, I feel like I am avoiding some pitfalls.

I still need one at point b to hold up the back of the motor, do you think it will be an issue?

 

Now this is a fun thing to follow.

 

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.