Machine the primary

[My_nanc]

When we machine the primary clutch can anyone explain or show picts how much is being taken off and how high their belt rides now. With my low gearing on my xtx and my engine mods i can use the extra shift now. I already cut down my secondary helix to allow it to move fully open. I believe with the 8dn belt and having my secondary open more i am close to a 1 to 1 ratio. I believe befor i was not getting a full 1 to 1.

 

[NOS-PRO]

This is on my Viper running the 8DN length belt. As you can see, the mark is .062" or 1/16"

****** This is a reminder that machining a clutch for overdrive must be taken very seriously and will void your clutch warranty******

You can machine .020-.025" (straight cut) off of each primary face at the bottom next to the main steel shaft.

 

[RJH]

That is a good picture..smart test to..nice jig...

Notice your belt tracks on the secondary..you are pretty well at the bottom of the secondary as it is.

I would recommend 1:1 and let your gearing do that speed work..

It is all about belt speed...

 

[RJH]

View attachment 127710

This is on my Viper running the 8DN length belt. As you can see, the mark is .062" or 1/16"

****** This is a reminder that machining a clutch for overdrive must be taken very seriously and will void your clutch warranty******

You can machine .020-.025" (straight cut) off of each primary face at the bottom next to the main steel shaft.

Impressive..

 

[Mills]

How are you avoiding secondary coil bind with this setup or do you have some coil bind?

 

[My_nanc]

Ya i can now b at the bottom with my 8dn belt and cutting a little off my secondary has allowed me to be there. With this as it shows on my marks i can travel down a 1/16 or so in my secondary to take full advatage of my clutch face. Befor it was not that low in the secondary. Now i can get a little more from my primary and will cut a little bit off it to do so. It will not be much but every little bit on both faces is a lot of extra shift ratio. Im not shooting for crazy speed just wnat to take full advantage of my clutch faces and shift ratio. As i said befor i dont think i was at a 1 to 1 full shift.

 

[My_nanc]

How are you avoiding secondary coil bind with this setup or do you have some coil bind?

No spring bind that i can tell. You can see the spring on right side in pix.

 

[My_nanc]

Oh ya and i also hav a blue secondary spring from big venum ckutch kit. Im shure my stock would be binding.

 

[My_nanc]

Also the best part of the 8dn belt is that you can ride so high in the secondary allowing a very low ratio for starting.

 

[jeff_yam]

View attachment 127710

This is on my Viper running the 8DN length belt. As you can see, the mark is .062" or 1/16"

****** This is a reminder that machining a clutch for overdrive must be taken very seriously and will void your clutch warranty******

You can machine .020-.025" (straight cut) off of each primary face at the bottom next to the main steel shaft

Is it ok to do that on my NA sled if I have done airbox mod, added MBRP trail can and a power commander? Do I need to have more power? Do I have to change my gearing? I currently have 24/50 gearing...

Thanks

 

[RJH]

Once a drive goes past 1:1 you have lost efficiency.....better to use gearing and let the clutch do what it is supposed top do..in my opinion.
Its good what he did..for other reasons

 

[Studroes144]

Is it ok to do that on my NA sled if I have done airbox mod, added MBRP trail can and a power commander? Do I need to have more power? Do I have to change my gearing? I currently have 24/50 gearing...

Thanks

Yes you can do this on an n/a sled, however if you don't have the power to use the extra shifting of the clutches then it's of no benefit. If you have 24/50 gears you have an rtx or ltx? What's your top speed? Seems like 105 is the magic number on snow with stock gearing regardless of whose clutch kit, some slightly more some slightly less. So if you're not to that point where you stuck at around 105 then machining for more shift won't help in any way. Given your mods, in all honesty I don't see any reason for machining, there's guys on here with quite a lot of additional hp adding parts on top of what you have and on snow it seems like they're seeing 105-108. Another thing to remember is that when machining for more shift you're essentially trying to shift your clutches into overdrive which also takes a lot more power to obtain, more than what I feel an exhaust and airbox mod can achieve. One guy to talk to on this is Cannondale, I know he's tried different clutch setups as well as different gearing and if I remember correctly his consensus is that with taller gearing he wasn't really able to get much if any more top end but was able to do top speed more consistently. Since conditions greatly affect sleds if focus more on consistency than that 1 time a year where you hit a perfect trail and can get a big top speed number.

 

[cannondale27]

Yes you can do this on an n/a sled, however if you don't have the power to use the extra shifting of the clutches then it's of no benefit. If you have 24/50 gears you have an rtx or ltx? What's your top speed? Seems like 105 is the magic number on snow with stock gearing regardless of whose clutch kit, some slightly more some slightly less. So if you're not to that point where you stuck at around 105 then machining for more shift won't help in any way. Given your mods, in all honesty I don't see any reason for machining, there's guys on here with quite a lot of additional hp adding parts on top of what you have and on snow it seems like they're seeing 105-108. Another thing to remember is that when machining for more shift you're essentially trying to shift your clutches into overdrive which also takes a lot more power to obtain, more than what I feel an exhaust and airbox mod can achieve. One guy to talk to on this is Cannondale, I know he's tried different clutch setups as well as different gearing and if I remember correctly his consensus is that with taller gearing he wasn't really able to get much if any more top end but was able to do top speed more consistently. Since conditions greatly affect sleds if focus more on consistency than that 1 time a year where you hit a perfect trail and can get a big top speed number.

Yup. Before gearing higher I was using every bit of both clutches with 8dn now after gearing higher I am not using the full clutches. Top speed stayed exactly the same but more consistent and believe it or not acceleration is also better. If looking for top speed look for more power or less drag to use what's there more effectively. It's not anywhere else.

 

[Studroes144]

To go along with that, what I found on my personal sled was that the secondary stopped shifting before the primary, this is with a stock helix intact. I'm sure some aftermarket helix's are designed to shift farther, Dalton helix in particular is so I had my Yamaha helix machines to the same specs as a Dalton helix, very simple to do, local machine shop charged me $10 and at the very least now I know the secondary isn't holding it back, should mention as well though that this is on a turbo sled which does have the power to push shift the clutches that far even with taller gearing. Like Cannondale said, it's all about power, if you are a trail rider that wants a fast sled work on consistency rather than that 1 perfect setup that only can be used once or twice a season.

 

[NOS-PRO]

Is it ok to do that on my NA sled if I have done airbox mod, added MBRP trail can and a power commander? Do I need to have more power? Do I have to change my gearing? I currently have 24/50 gearing...

Thanks

As mentioned, you could change gearing to get the same top end results without machining.

As for me, I couldn't sacrifice my bottom end as I needed to be as quick as possible off of the line for asphalt. On trail it performed well also but I didn't want to change gearing because I do 85% off trail and wanted the lower gearing.