Let's talk rear suspension theory.

[Majourlittle]

I have brought this up before with little result, but I think that I will bring it up again. On my 89 Elite-E with a dio swap, I have run into a few issues that I want to discuss with the populace.

Why does the scooter engine hanger pivot at two positions? I know that it is mildly restrained at the front end by the tongue, but it still moves as the bike goes down the road. The engine also pivots at the motor as well. I have often wondered why there is a three link bar between the frame and the rear wheel.

What would be the effect of making a solid mount off of the frame that only pivoted at the motor connection? Is there any drawbacks to this type of setup. I believe that this would allow better control of the rear suspension with less flex.

Also, has anyone noticed any issues with the monoshock being off to one side of the rear wheel?

[Wheelman-111]

Greetings:

I have no wobble issues with Flash at any speed.
The engine hanger is flex-mounted because if it were solidly attached, the 2-Smoke Buzz would rattle the fillings out of your molars. Also the loose mount makes it possible to make the whole thing a little lighter - solid mounting would jar the frame a lot harder and require more reinforcement than is needed with Honda's system.

YMMV

[Majourlittle]

I disagree.

With the front end of the mount pinned in place, an extreme force would to through the frame just as much as a solid front mount. The absorbtion would take place in the rear spring.

If you were to take the existing mount and weld it down, the only extra support you COULD require is a pipe brace from the engine mount to the frame. The weight would be negligble.

In regards to the vibration, I think that you are right to a degree. The rubber isolation bushings would sofen the vibrations, but there are plenty of one cyl setups that are siolated with a little piece of rubber. Maintaning the isolators in the engine and the engine side of the mount would be sufficient, and reduce the flex you could have at the frame side isolators.

I think that the best course of action is to just build it. I think we could speculate all day long on this.

[Trafficjamz]

The main purpose of the double pivot hanger is to dampen vibrations.

You can weld the front solid. I have done it on some of my drag bikes.

I would not do it on a daily driver, the vibrations would be too much for me.

As far as the mono shock goes......I have had zero issues.

Why do you want to change the hanger?

[kingkamehameha]

I disagree.

With the front end of the mount pinned in place, an extreme force would to through the frame just as much as a solid front mount. The absorbtion would take place in the rear spring.

If you were to take the existing mount and weld it down, the only extra support you COULD require is a pipe brace from the engine mount to the frame. The weight would be negligble.

In regards to the vibration, I think that you are right to a degree. The rubber isolation bushings would sofen the vibrations, but there are plenty of one cyl setups that are siolated with a little piece of rubber. Maintaning the isolators in the engine and the engine side of the mount would be sufficient, and reduce the flex you could have at the frame side isolators.

I think that the best course of action is to just build it. I think we could speculate all day long on this.

Weld a soild motor mount and have to keep re tightening every bolt on your engine and let us know how that goes.

[Majourlittle]

...Usefull Insight...

I need to lengthen the hanger to reduce the wheelie action I am getting right now. I feel that adding length to the hanger will create much more leverage on the existing hangar and induce quite a bit of flex and some issues with handling. By pinning the front of the hangar to the frame, I can increase its rigidity and reduce the amount of climb I get from the motor.

The second idea I had with the shock is to reposition it to the front of the motor like the older sportsbike monoshock. I am having issues with it rubbing and it seems to be a large issue with trying to retrofit the af16 into the older frames.

T-jams, do you have any detailed pics of your drag bike hangars?

[Wheelman-111]

Greetings:

Owning Evo Sportsters for 12 years, I feel I know something about vibration. Legendary V-Twin solidly mounted (until 2004) to the frame make Red LocTite the Harley rider's Best Friend. If you have a can o'paint that's congealed to jellied crust, strap it to my rack for a 15 -minute ride in 3rd gear.
Quoth The Majour:

The motor produces vibration, wheather it is isolated or not. A hard or soft mount won't change the vibration that the engine feels. You argument is invalid.

Quite right - the Engine won't be subjected to much more vibration with a solid mount. Maybe a little though, since most of it comes from the front-to-back swing of the crank. If it's pinned to a heavy mass like the frame, it has to absorb more of it internally.

That said, the tingling in your handgrips, saddle, floorboards etc. may become considerably more bothersome to the Rider. I'd hate to think what'll happen to all those delicate panel mounting tabs. Not an issue for a dragster like Jamz's, but a Daily Rider? You'll grow tired of it quickly.

[eliteguy50]

I disagree.

With the front end of the mount pinned in place, an extreme force would to through the frame just as much as a solid front mount. The absorbtion would take place in the rear spring.

Wrong. In this instance, the mount acts as a crumple zone. The monoshock would twist the frame to absorb the energy when it bottoms out. I know this from experience, not hypothesizing.

[Wheelman-111]

Greetings:

While tuning the VM26 carb - Don't ax! - yesterday, I had occasion to really observe the behavior of the idling engine from below as it sat on the centerstand. I suggest you duck your head down there and see just how much jumpiin' around the front of the crankcase does on its rubber-bushing-ed mount. More jittery than Robert Downey Jr. after a crack party.

[Majourlittle]

Thats why I am concerned. That movement translates to the rear wheel and could induce some sway. Some of that movement is caused by the wingarm itself. I pulled the rear of the bike off last night and I noted that I had constructed my hangar so that it doesent free-move and is rubber isolated. I have not noticed any uncomfortable vibrations. With that said, I think that is a comfortable medium between where I proposed and where it was originally.

[Wheelman-111]

Greetings:

The mounting bracket's rubber dowel ensures all movement is confined to the Pitch plane, sort of like a secondary "suspension". The hard bushings at the crank bosses permit very little movement in the planes of Roll and Yaw. I don't experience wobbles at any speed up to 70, so not sure there was a significant issue.

[Trafficjamz]

...Usefull Insight...

T-jams, do you have any detailed pics of your drag bike hangars?

[maddog]

Dude, your exhaust is hanging and stock rims, invedt another $1,000 and get done right

[bakaracer]

There is nothing wrong with how honda designed the motor mount setup. I roadraced with it the way it is up to 85mph with no issues. Plus if you knew more than the honda engineers, you wouldnt be on here posting.

[Trafficjamz]

Dude, your exhaust is hanging and stock rims, invedt another $1,000 and get done right

I don't use that pipe anymore, my scorpion revs much higher.

That is a stock MET rim, and is just fine for drag racing. The lighter the better.