Why Is the Swingarm Mounted to the Transmission and not the Frame?
 

Hi, I'm new.

It might seem like a stupid question but I haven't been able to find the answer anywhere.

In the Dyna models the swingarm is mounted directly to the rear transmission. Why did Harley Davidson design it this way?

The older models (FLH, FXR ect) were not mounted this way, nor are the modern bikes that Harley makes such as the Road Kings, Sportsters ect.

It seem like it'd be detrimental for the Dyna since the engine is rubber mounted, which would mean that the swingarm is not solidly attached at any point onto the frame, which I imagine would give it more slop than if mounted to the frame.

It also seems like it would be mechanically weaker since the swingarm is mounted to the transmission which is in turn mounted to the motor, so ultimately the rear wheel is only attached to the bike by a few bolts that hold the transmission to the engine.

Again I don't know, I'm only guessing. Please correct me if I'm wrong anywhere.

Ultimately my question is why did Harley design it this way. What are the advantages, if any to this design?

As an aside why did Harley decide to attach the transmission to the motor in the first place? Why not leave them separate as they were in shovelheads and before.

Any info would be greatly appreciated.

Thanks!

:icon_munching:

Like when the Germans bombed Pearl Harbor?
Look closer.

It makes sense that an engine/transmission bolted together would be stiffer (although why not just make the frame stiffer?)
But wouldn't having the swingarm bolted to the transmission/engine make the whole thing more flixible since now the rubber is allowing some slop/flex between the engine and frame?

I don't catch your drift. What do you mean by this?

If the swingarm were not mounted to the transmission, belt tension would be impossible to maintain on rubber mounted models.

Softail can be bolted to frame because the engine is hard mounted to frame.

Too many words. No paragraph separations. Can not decipher.