Factory Pro Blue Magic Shift Spring

[Somchai]

Welcome Patrick, good to see a specialist for springs entered the forum

[toEleven]

Originally Posted by SLOWn60

...[Wall of Text]...

I have no idea how this relates to springs or transmissions, but you've made me glad I'm single. I usually have to go to work, where most of my team is either divorced or on marriage 2 or 3, for that.

[mgentz]

Will the 92081-112 spring be stiffer in a 2009 250? The spring is longer than stock....

Originally Posted by Ghostt

Measurements of Factory Pro Blue Magic Shift Spring

Okay it arrived today, thank you @DCMoney so on to the measurements,

Length=35.1MM
I.D.=5.4mm
O.D.=7.9
Wire diameter=0.9MM

Pinch test, noticeable a little bit stiffer compared to the 92081-112 SPRING.

Will do a ride report after my ride tonight, so stay tuned.....


Picture below:
Left=92081-112 SPRING
Right=Factory Pro Blue Magic Shift Spring

[Kestrel]

Originally Posted by mgentz

Will the 92081-112 spring be stiffer in a 2009 250? The spring is longer than stock....

Another misconception earlier in this thread was that length has no bearing on spring rate.

That's not true. If we cut a spring in half, we reduce the number of active coils.

Recall, spring rate goes by...



where...

R = Spring constant
G = Modulus of shear N/mm2
d4 = wire thickness to the power of 4
D3 = Outside diameter to the power of 3
n = active coils

.. as n gets smaller, k (what they call R here) gets larger. This makes sense intuitively if we think about breaking a pencil. Pencils flex a little, but if you break them, you've got less leverage on the shorter piece, and it appears 'stiffer'. A coil spring is just a torsional load applied to a rod, and we can treat it to the same. Longer is easier to flex, shorter... not so much.

So again... we really need to find out what the spring constant is for all of these springs, as well as the compression lengths at min and max deflection. At that point, it's easy to find a cheap solution.

[Ghostt]

Originally Posted by mgentz

Will the 92081-112 spring be stiffer in a 2009 250? The spring is longer than stock....

If recall somewhere in this thread someone with a NewGen Ninjette tried the spring, I think they said it was the same.

But I haven't verified this, as I don't have access to a NewGen.

[Ghostt]

Originally Posted by Kestrel

Another misconception earlier in this thread was that length has no bearing on spring rate.

That's not true. If we cut a spring in half, we reduce the number of active coils.

Recall, spring rate goes by...



where...

R = Spring constant
G = Modulus of shear N/mm2
d4 = wire thickness to the power of 4
D3 = Outside diameter to the power of 3
n = active coils

.. as n gets smaller, k gets larger. This makes sense intuitively if we think about breaking a pencil. Pencils flex a little, but if you break them, you've got less leverage on the shorter piece, and it appears 'stiffer'. A coil spring is just a torsional load applied to a rod, and we can treat it to the same. Longer is easier to flex, shorter... not so much.

So again... we really need to find out what the spring constant is for all of these springs, as well as the compression lengths at min and max deflection. At that point, it's easy to find a cheap solution.

As I've stated, the difference is noticeable with the upgrade OEM spring over the PreGen Ninjette OEM, but not as stiff as the Blue Magic Spring, and it's a lot cheaper.

I've tried both, and in the end I went with the upgrade OEM spring, as the Blue Magic Spring was a bit too stiff for street use IMHO.

[Kestrel]

Originally Posted by Ghostt

As I've stated, the difference is noticeable with the upgrade OEM spring over the PreGen Ninjette OEM, but not as stiff as the Blue Magic Spring, and it's a lot cheaper.

I've tried both, and in the end I went with the upgrade OEM spring, as the Blue Magic Spring was a bit too stiff for street use IMHO.

I think it's the ticket for most people, too. Spring rate scales by wire diameter to the fourth power.... So just a tiny bit more thickness makes a big, big difference in the stiffness.

[sharky nrk]

The comparison we need is factory new gen vs OEM upgrade spring, did anyone get those two side by side. I have the factory pro in my track bike but refuse to spend another $40 on a spring lol.

[sharky nrk]

I suppose I need to just pick up one of these OEM upgrade springs on my next order and measure the free length, wire thickness, and# coils or somebody send Patrick the all the springs so he can test them and finalize the rates and put it all to bed lol.

[mgentz]

Originally Posted by Kestrel

Another misconception earlier in this thread was that length has no bearing on spring rate.

That's not true. If we cut a spring in half, we reduce the number of active coils.

Recall, spring rate goes by...



where...

R = Spring constant
G = Modulus of shear N/mm2
d4 = wire thickness to the power of 4
D3 = Outside diameter to the power of 3
n = active coils

.. as n gets smaller, k gets larger. This makes sense intuitively if we think about breaking a pencil. Pencils flex a little, but if you break them, you've got less leverage on the shorter piece, and it appears 'stiffer'. A coil spring is just a torsional load applied to a rod, and we can treat it to the same. Longer is easier to flex, shorter... not so much.

So again... we really need to find out what the spring constant is for all of these springs, as well as the compression lengths at min and max deflection. At that point, it's easy to find a cheap solution.

Assuming the same wire diameter, if the length is longer it will be more preloaded, i.e. moving the rate up the scale right? this would make it stiffer?

[mgentz]

Originally Posted by sharky nrk

The comparison we need is factory new gen vs OEM upgrade spring, did anyone get those two side by side. I have the factory pro in my track bike but refuse to spend another $40 on a spring lol.

I have both. What do you want me to measure?

FYI, my stock new-gen spring only has 10,000 miles on it.

[sharky nrk]

Originally Posted by mgentz

I have both. What do you want me to measure?

FYI, my stock new-gen spring only has 10,000 miles on it.

free length, wire thickness, coil diameter, number of coils

also if you could do a subjective "which feels stiffer"

mostly wondering if the OEM upgrade spring is between the newgen and the factory pro of if the OEM upgrade is between pre and newgen

[sharky nrk]

Originally Posted by mgentz

Assuming the same wire diameter, if the length is longer it will be more preloaded, i.e. moving the rate up the scale right? this would make it stiffer?

assuming both springs have the same rate, the spring with the longer free length will have greater preload and provide a resultant force that is greater for that specific installed length yes

[Kestrel]

Originally Posted by sharky nrk

free length, wire thickness, coil diameter, number of coils

also if you could do a subjective "which feels stiffer"

mostly wondering if the OEM upgrade spring is between the newgen and the factory pro of if the OEM upgrade is between pre and newgen

What really matters at the end of the day is spring rate of each spring. The other stuff doesn't do anything for us unless we know the modulus of elasticity of the metal... which we certainly don't. At the end of the day, we need K.

Originally Posted by sharky nrk

assuming both springs have the same rate, the spring with the longer free length will have greater preload and provide a resultant force that is greater for that specific installed length yes

If the rate is the same, then the longer spring would have to have been made from a weaker metal, or from a thinner diameter coil. If you DO make the spring from the same materials but have it longer, technically the rate is lower. Unless you preload the crap out of it, you won't necessarily get more force.

Ultimately, we need to figure out a few things...

1)What is the distance from the shift star thing to the top of the bolt / cap, once everything is bolted down into place in the engine

2)What are the spring rates for each of the springs

The # of coils and all of the other information doesn't really matter in practice. Once you know those two things, it's simple to solve for the rest with good old F=KX.

[Ghostt]

I would like to know the difference as well for NewGen Vs Blue Magic.

The OEM upgrade spring is used in a lot of models, for a lot of years.

I'd be curious to seem the difference between the OEM upgrade spring 92081-112, and the NewGen spring 92144-1580. Which according to Kawasaki it fits PreGen and NewGen models.

[sharky nrk]

Originally Posted by Kestrel

What really matters at the end of the day is spring rate of each spring. The other stuff doesn't do anything for us unless we know the modulus of elasticity of the metal... which we certainly don't. At the end of the day, we need K.



If the rate is the same, then the longer spring would have to have been made from a weaker metal, or from a thinner diameter coil. If you DO make the spring from the same materials but have it longer, technically the rate is lower. Unless you preload the crap out of it, you won't necessarily get more force.

Ultimately, we need to figure out a few things...

1)What is the distance from the shift star thing to the top of the bolt / cap, once everything is bolted down into place in the engine

2)What are the spring rates for each of the springs

The # of coils and all of the other information doesn't really matter in practice. Once you know those two things, it's simple to solve for the rest with good old F=KX.

The assumption was made the K was the same for that specific question about preloading two springs of the same rate (not my assumption mind you) and yes the material or geometry would be different to allow for two springs to be the same rate but not same length.

In asking for the specific geometry of the springs measured, one would be making the assumption (this one being my assumption) that the material selected for the two OEM springs would be similar and as a result have a similar modulus. In the end if calculating the different rate assuming similar (same) modulus provides one spring is X amount stiffer than the other, we gut check with the requested "feel" test of stiffness.

I did for the record recommend sending them to you to just test the dang rates lol.

[mgentz]

Originally Posted by sharky nrk

The assumption was made the K was the same for that specific question about preloading two springs of the same rate (not my assumption mind you) and yes the material or geometry would be different to allow for two springs to be the same rate but not same length.

In asking for the specific geometry of the springs measured, one would be making the assumption (this one being my assumption) that the material selected for the two OEM springs would be similar and as a result have a similar modulus. In the end if calculating the different rate assuming similar (same) modulus provides one spring is X amount stiffer than the other, we gut check with the requested "feel" test of stiffness.

I did for the record recommend sending them to you to just test the dang rates lol.

You want me to ship these out for testing? I have the OEM upgrade and the New Gen springs. I think Ghostt has the rest...

[sharky nrk]

If you don't mind I think it would be great if we could get them all rate tested side by side but if not, no sweat.

[corksil]

I put in my blue spring 'upgrade' today.

First impression is that gear changes required more foot effort. Previously I could gently nudge the bike into gear from neutral. With the blue spring installed it took more downward pressure.

Definitely felt different from OEM, so I checked chain tension (which can also cause shifting issues) and it was a tad loose. Tightened chain to spec and went for a ride. With the blue spring -- shifting requires more force on the shift lever to change gears.

I can see how an extremely worn old track bike might go into neutral when shifting from first to second with your primary focus on the line you're about to take through the first turn. I've done it a few times myself when my focus was moreso on maintaining (too much) speed into a turn. The blue spring is a more conscious effort to shift.

Apart from that, no change.

Bike is around 30k miles, relatively new chain and sprockets.

I said I'd post a review once I installed it so here it is.

[toEleven]

Originally Posted by corksil

...The blue spring is a more conscious effort to shift.

Apart from that, no change.
...

So it's not magic then? Bummer. Thank you for the review.

[Skullz]

The new spring is no different than learning something new, once you get some time under your belt with it, you'll be accustomed to it and will no longer think about the effort it takes.

[DCMoney]

Originally Posted by corksil

I put in my blue spring 'upgrade' today.

First impression is that gear changes required more foot effort. Previously I could gently nudge the bike into gear from neutral. With the blue spring installed it took more downward pressure.

Definitely felt different from OEM, so I checked chain tension (which can also cause shifting issues) and it was a tad loose. Tightened chain to spec and went for a ride. With the blue spring -- shifting requires more force on the shift lever to change gears.

I can see how an extremely worn old track bike might go into neutral when shifting from first to second with your primary focus on the line you're about to take through the first turn. I've done it a few times myself when my focus was moreso on maintaining (too much) speed into a turn. The blue spring is a more conscious effort to shift.

Apart from that, no change.

Bike is around 30k miles, relatively new chain and sprockets.

I said I'd post a review once I installed it so here it is.

The point of this spring is to stop your bike from going into false neutrals higher in the gear box, not to stop you from hitting neutral between 1st and 2nd...

None of the tracks I race on require me to be in 1st gear for more than 2 seconds, after that the lowest I would ever see was maybe 3rd.

My false neutrals were happening most between 4th and 5th, on an engine with less than 4k miles. The blue spring fixed.

[mgentz]

Originally Posted by DCMoney

The point of this spring is to stop your bike from going into false neutrals higher in the gear box, not to stop you from hitting neutral between 1st and 2nd...

None of the tracks I race on require me to be in 1st gear for more than 2 seconds, after that the lowest I would ever see was maybe 3rd.

My false neutrals were happening most between 4th and 5th, on an engine with less than 4k miles. The blue spring fixed.

I have only ever experienced 1 false neutral, and it was between 4 and 5th as well. I put in the OEM upgrade spring and will try it this spring.

[tgold]

Originally Posted by alex.s

length and spring rate are not related. and 12n/mm is a hypothetical spring. you probably mean the blue magic spring is longer. but since we dont know the spring rate, for all we know it could be the same rate as stock but slightly longer to force preload without a washer

Yes, length and spring rate are related. Measure the rate of a spring then cut some coils off it and remeasure it. You will find that the spring rate has just increased.

What you are really doing with a spring is you are twisting it along the lengthwise axis of the wire. A spring is just a torsion bar in coiled form. To demonstrate this to yourself, take a 3ft piece pf 1/8" by 1" aluminum flat stock and clamp one end in a vise. Then take an adjustable wrench, tighten it down on the other end, and then apply force to twist the aluminum in the lengthwise axis. Note the feel of how much force that you have to apply for a given distance. Now cut the aluminum in half and repeat the process with the wrench. You will find that you have to apply more force to get the aluminum to twist the same distance.

If you want to increase the spring rate of your stock shift detent spring it may be possible to do it by simply cutting a few coils off the stock spring, Making sure that the cut end is flat and perpendicular as possible to the spring's lengthwise axis. Then you replace the distance that you cut off with a spacer of a length equal to the amount of spring that you cut off. and you now have a stiffer spring. The caveat is that you must make sure that you don't cut too much off the spring and run into coil bind.