The New Secondary Brain Child Is Done And Is Easy To Do

[blueironranger]

So on Sunday I had to move a stock Phazer and it seemed to be more "jumpy" off the line, if that makes sense.

I spent sometime reading and thinking about it. Aaen's book has a good little table in it that talks about what you want to change and what components do that. It says that for more aggressive acceleration you can increase the helix angle or decrease secondary pretension.

I'm currently running a 43* helix with the green spring at 60* pretension. I chose 60* as it seems like a similar starting point that a lot of people have been using but more with the 41* helix. With lower pretension the motor can drag the belt in faster and load the motor harder.

So if I go to lower pretension I should be able to get harder acceleration also get a few more rev at the top. Also as long as the belt is not slipping then this should reduce belt heat too.

Can someone confirm the logic?

Spring rate controls most of the shift out and twist controls backshift and some of the shift out. More twist = more rpm as the speed climbs and also adds a touch more rpm across the whole range. This is not the preferred method for RPM control but works for fine tuning. That said, with a 800rpm window we really don't need fine tuning, as long as your clutching stays in the 10,800-11,600 window there isn't much to gain. I will say staying below 11,300 peak seems to help MPG quite a bit. Max MPG is achieved at peak Torque, 8,800 rpm in our case and my sled cruises right at 8,800rpm @ 50mph!

 

[Voda2000]

So if I understand right the spring rate and angle of helix control the profile of how the secondary opens and the preload lets you move the cushift point up and down the rpm curve.

So increasing the preload with move the shift out point up the rpm band but the way it gets there will be the same?

 

[blueironranger]

So if I understand right the spring rate and angle of helix control the profile of how the secondary opens and the preload lets you move the cushift point up and down the rpm curve.

So increasing the preload with move the shift out point up the rpm band but the way it gets there will be the same?

For the most part, more twist = harder for the pucks to "climb" the helix ramps, also quicker to slide back (back shift). Easiest way to tell if you need more twist is if your rpm is low or you have a bog after let off the throttle abruptly and hit it again. Another is if your running hardpack and you loose too much RPM by drifting out into powder.

 

[jgustman]

My reverse secondary is up for sale in the free classifieds. Sold the sled. Just put the damn thing on...

 

[Voda2000]

Meant to get back to this sooner but I went to 70 degrees and much better. The RPMs are spot on and it pulls like a freight train.

 

[blueironranger]

Meant to get back to this sooner but I went to 70 degrees and much better. The RPMs are spot on and it pulls like a freight train.

I also tried 70* on my last trip and the backshift is very aggressive and works great for powder but it really caused my rpm on the trail to climb. I gained almost 300rpm going from 60 to 70 which, to me, means that it's at the limits of how much preload to use.

 

[ATV PRO #11]

I gained almost 300rpm going from 60 to 70 which, to me, means that it's at the limits of how much preload to use.

Good info.
Would this mean you would move to the next secondary spring colour Blue?

 

[blueironranger]

Good info.
Would this mean you would move to the next secondary spring colour Blue?

Not for me, its just telling me that backshift isn't going to get any better than it is without killing efficiency. Only reason to go the next step up is if I was experiencing belt slip which would also require heavier clutch weights to keep the RPM in check.

 

[Voda2000]

For me it was shifting too soon and I was running about 300rpm under peak.

Given that a Vector runs the green spring stock with 120 hp I doubt that the Phazer would need a heavier spring.

 

[SnoNinja]

I installed reverse secondary in Ditch Cricket a couple weeks back. Running stock primary spring, Viper Big Venom weights set up very similar to my Viper, Thunder Products blue secondary spring and 41 helix. Rpms spike to 11,800 and settle right in to a stable 11,500 on groomed trail. Not much rpm lose moving into powder, but need some more test time to confirm. Overall, very happy. Thanks to all that contributed to this thread.