i went ahead and ordered the whole kit..front and back.....it does come with directions.....i love the way mine handles....don't know why you would only install the front ?the rear does make a difference..i have tried it.....

 

Dyna's have a twitch sometimes which you can feel in the curves. The rubber isolated engine only has one solid mount, top mount, between the cylinders. What happens is that the engine will bind, between the front and rear motor mounts, due to stresses from the belt and torque applied to the rear wheel as it moves up & down. It then unloads, causing the twitch, and then repeats. Have you ever notice how a V-8 engine rocks on it motor mounts, due to torque and engine rotation? While the V-8 has side engine mounts, the V-Twin has front and rear engine mounts and the engine is connected to the rear swingarm via the drive belt which will introduce a binding or side force on the motor mounts. As the mounts load there is only so much room before it has to unload.

The Spruthe Positrak, and others like it (True-Trak), locks or ties the engine to the frame so that this side load can only be applied in the vertical plane, thus eliminating the "twitch".

Hope this helps.

 

The swing arm is bolted to a rubber mounted engine, and transmission. The rubber engine and trans mounts allow side to side and up and down motion. Since the swingarm is rubber mounted via the transmission, the rear wheel and swing arm will move side to side when you throttle it out of a corner causing a very wierd feel. The sputhe and truetrac eliminate the side to side motion and keep the engine, trans and swing arm in line with the frame eliminating the rear wheel wander. Something HD should have done, and they know it!

Same thing dlstanf2 said, I just dumbed it up.

 

Could you expect the same from the softail models?

 

I don't believe so because the TC B is a solid mount as opposed to the TC A motor which is rubber mounted.

 

Not really. His description of the problem is not accurate. Yours is.

 

I have noticed the wandering, self steering rear end on my Dyna, ONLY
when exceeding 60 mph in turns. Feels like the rear is following really badly lined up rain grooves. Have not noticed it AT ALL on tight radius turns up to the said 60 mph. I ride pretty aggressively (for a cruiser) and my engine puts out plenty more steam than stock (about +67% more) which would surely test the mounting system of my Dyna.
The photos of the Harley are with the stock Harley motor mount, the bike handled as if on rails......... below 60 mph.

riding other bikes semi-aggressively ....

 

Because, I'm cheap, the rear is a pain to mount, and the front solves at least 80% of the problem. I don't ride really hard.

 

I didnt really notice it on mine till I played with the engine. Now with 110tq it wanders pretty bad when I twist the throttle in a turn. My brother was behind me and said it looks like the rear tire has a bad wobble.

 

I love this guy's pictures!

You're killin' it on that Aprilla!

I love my True Track, I'll never take it off. It really helps with speedy cornering