Using 6th gear over drive correctly and vibration

[Mikind7]

Not trying to pick on you Mikind, just using your post as an example of the prevailing thoughts.

Went & looked at the advertising & publicity blurbs that came out with the 'new 1330' motor & once you get past the top level guff, most of it also refers to the 'new 6 speed overdrive gearbox' or uses similar terms to describe the gearbox internals....with a 1:0.91 drive ratio - so from that I'd guess that at least 6th IS an overdrive gear. :dontknow:

I stand corrected.

 

[PaladinLV]

I have felt it in various gears but mostly in 6th gear, I just stretch out the gears a little more so I no longer bog the engine,

If you own a 1330 SE6, your engine will not start to bog until it @ 40 mph. That is the fact of the situation.
I travel all around town at 45 and in 6th. Never a problem and always enough torque to pass if required.
I will add, IF I need to accelerate quickly, I will then drop to 5th, but only for quick acceleration in town.

Not having an SM6, it may be different, but SE6 does not need to be S T R E C H E D out.
BTW - Once I had my tires properly balanced and laser aligned, my vibration disappeared. Which when it occurred was a speed factor 75 - 80 and not an RPM factor.

AJ

 

[Tom in NM]

That "explains" it . . . .

Hope your right and adjusting the belt or slapping a belt tension device on will work for you but I don’t think it will. Lets keep fingers crossed.

stretching out the gears and especially between 5th and 6th eliminated the problem for me. Never accelerate in 6th gear if your at or under 67/68 or your going to feel it big time. Drop down to 5th and accelerate to 70 then push into 6th. You can cruise in 6th at 65 but don’t accelerate.

. . . . . but given the number of nit-pickers that ride Spyders, I am sure the debate and whining will rage on.

:thumbup: Thanks for posting your solution Taz. :thumbup:

I have never had the vibration issue and now I am beginning to understand why. When I first heard about the 'issue' I went out next tried to find it on my F3. Not there. It never occurred to me to engage 6th gear at anything under 70mph - like, who would do that?

When you first posted this thread, I went out and tested shifting into 6th around 60mph - and yes, there was "vibration" right around 70mph as I acelerated. As someone else mentioned, it felt a lot like riding on grooved pavement- not bad, but noticeable.

I am no expert, so I don't know if it is the engine bogging down, belt vibrations/harmonics, the nature of the new gearbox or even something else, but ( for me ) shifting as you recommended eliminates the effect. I would expect it would for other F3 riders, but it will mean adjusting their shifting habits - and it is easier to just complain about it.

So, about 2 weeks have passed since you posted " a fix " and nobody seems to have tried it, or thanked you or corrected you. Seems your meathead comment was spot on too.

Taz, you are batting a thousand, keep it up!

Tom

 

[vondalyn]

me too

I've also never/rarely experienced the vibration and I also shift at higher points. I would never shift to 6th at 45. only at that point do I even think about shifting to 5th and that's more like 48 before I shift to 5th. If I'm cruising along at 45, I'm still in 4th. (oops, said 3rd -- need more coffee this morning!)

 

[Pirate looks at --]

I purchased an F3 and felt the vibration at 65+ right away. A friend of mine that knows engines and bikes in general hopped on and took it for a 20min ride. When he got back I asked him if he felt it too. He said he felt it but it was not the belt. He said you have to use the 6th gear correctly or your bogging the engine. He said push the 5th gear out to 70 to 75 before moving into 6th. 6th gear is an over drive and should only be used at higher speeds. When passing, or curising at higher speeds. Always drop it back into 5th gear when your speed drops back down to 65 if you dont and try to accelerate you will feel the vibration.

So I tried this over the next few days and problem was solved.

Is it dangerous to be "cursing at higher speeds"?:roflblack:

 

[sledmaster]

Has anyone posted the video of the belt resonating yet? If not I will find it and see if I can get it posted.

 

[sledmaster]

Drive Belt Harmonic Vibrations

OK, here is some heavy info on the drive belt harmonic vibrations and the video of a 2012 RT at 75-80 mph in 5th gear.

The Spyder drive belt is a tensioned string system that transmits the drive pinion torque to the rear sprocket via the tension of the upper part of the belt. The natural response of a string system is to vibrate when stretched and released at different speeds and strengths. The accumulated energy of these movements in the belt will be dissipated throughout the entire vehicle through the drive pinion and the rear sprocket.

A momentary belt vibration may be felt when the vehicle is driven under increased load/torque conditions (acceleration and/or going uphill). When the belt tension is within specification, the phenomenon may occur between 3800rpm and 4300rpm in 6th gear on 1330 engines (or between 4700rpm and 5500rpm in 5th gear on 991 engines). This vibration is felt through the handle bars, the foot rests and the seat. The harmonic vibration described here is considered "normal behavior" for such a belt drive system. In no cases is there any damage produced to the unit's mechanical components by this harmonic vibration.

Although belt vibration cannot be entirely eliminated, changing the belt tension will change the RPM/Speed at which the vibration occurs and the amplitude of its occurrences. Adjusting the drive belt tension lower will reduce the vibration level. Under high load/torque conditions, the vibration levels are diminished in amplitude and the RPM which the vibration occurs is lowered by roughly 400rpm.

For someone driving regularly between 68 and 75mph having a lower belt tension means they will feel a belt vibration when going through speeds of 62 to 65mph but at a lower amplitude, and feel less vibrations under acceleration and cruising speed. For someone driving regularly between 62 to 65mph having a belt tension set at specification means they will not feel as much the belt vibration since it occurs at higher RPM/Speed 68 and 75mph.

Statically, the belt tension is based on the distance between the drive pinion and the rear sprocket. The belt can be preset to a specific value using the tension adjustment procedure. While standing on its wheels, the belt tension of the Spyder increases due to the rotation motion of the swing arm. Further additional weight on the vehicle (driver, passenger and luggage) further increases the static tension of the belt.

Dynamically, the big picture is that the belt tension continuously varies with the road surface irregularities. Furthermore, to transmit torque from the drive pinion to the rear sprocket, the given amount of tension is decreased from the lower portion of the belt and transmitted to the upper portion of the belt. The inverse is also true when the vehicle is under deceleration. The amount of tension transferred depends on the acceleration or deceleration of the vehicle and slope of the road.

The belt tension is the factor which determines the belt vibration. The engine speed at which vibration would occur depends solely on the tension of the belt since the length and mass of the belt remains relatively constant. More vibration is transmitted to the vehicle when the tension is high. This effect can be explained by the fact that higher tension implies higher stiffness and higher stiffness implies higher transmissibility. This also explains why even though more vibrations are observed on the lower portion of the belt, only the vibration of the upper portion of the belt is strongly felt on the vehicle due to its higher transmissibility (because it has a higher tension in the majority of driving conditions).

At constant speed and zero road slope, the upper part of the belt has a higher tension than the lower part of the belt due to aerodynamic resistance. Under acceleration and/or hill climb conditions, the upper part of the belt further increases in tension. The degree of acceleration or hill climb proportionally dictates the engine speed at which occurs the belt vibration and the amplitudes of vibration transmitted to the vehicle.

By reducing the tension of the belt, the transmitted vibration at very low torque conditions can be completely removed. The transmitted vibration at higher torque is similar to that of the specification belt tension but occurs at slightly lower RPM/speed.

So basically, if you experience unpleasant vibrations have your drive belt tension checked at three different points of rotation of the rear wheel/sprocket and see how it varies, and compares to the vehicle's specification. If the belt tension changes more than 250N between 2 readings this would indicate an out of round rear sprocket which should be replaced. Otherwise, you can adjust the tension to change the speed and amplitude at which it occurs.

That's the physics of what's happening, folks.