Primary spring Question

[Doc Harley]

My primary is trying to tell me something. While I have no streaks of belt slippage, I am seeing the primary turn gray with belt dust and belt temps are manageable, but could always be cooler.
I'm assuming I need just a slight touch of additional pressure on belt, throughout the RPM.
The ultimax belt I have is showing approximately 1 mm of wear compared to new.
Max RPM is 8900 now. So I'm assuming more weight would help at the cost of dragging my RPM down further.
Was hoping a spring change might help, and I'll adjust accordingly.
Looking at this chart and would like some one to provide clarity as to what I'm looking at.

 

[74Nitro]

My primary is trying to tell me something. While I have no streaks of belt slippage, I am seeing the primary turn gray with belt dust and belt temps are manageable, but could always to cooler.
I'm assuming I need just a slight touch of additional pressure on belt, throughout the RPM.
The ultimax belt I have is showing approximately 1 mm of wear compared to new.
Max RPM is 8900 now. So I'm assuming more weight would help at the cost of dragging my RPM down further.
Was hoping a spring change might help, and I'll adjust accordingly.
Looking at this chart and would like some one to provide clarity as to what I'm looking at. View attachment 177665

You're looking at a chart that applies to older Yamaha sleds.
You need the long spring chart.
Colors are beside each other instead of on top of each other like above.

 

[Doc Harley]

You're looking at a chart that applies to older Yamaha sleds.
You need the long spring chart.
Colors are beside each other instead of on top of each other like above.

Corrected, ty 74Nitro.

 

[snowdust]

Sounds like you are close and have a belt temp gauge. Why not play with secondary and watch belt temps? Keep in mind any changes will change RPM. Weaker primary spring = lower rpm, but so does same primary spring and heavier weights. I'd increase and decrease the secondary by 10 degrees at a time and test. Lowest belt temps for the win.

 

[rev them up]

Just be aware if you are running Dalton it will act differently then a Yamaha spring at the same rate. I run a Yamaha G-W-G in my Nytro(45/136). If i put a Dalton b/b spring in(53/133) i lose some op rpm. I was told that there is a 10+lbs finale rate difference between the 2.

 

[Doc Harley]

Sounds like you are close and have a belt temp gauge. Why not play with secondary and watch belt temps? Keep in mind any changes will change RPM. Weaker primary spring = lower rpm, but so does same primary spring and heavier weights. I'd increase and decrease the secondary by 10 degrees at a time and test. Lowest belt temps for the win.

Listening to your words, I assume you'd want to go 10° lighter on the twist? I mean start with that?!?!

Just be aware if you are running Dalton it will act differently then a Yamaha spring at the same rate. I run a Yamaha G-W-G in my Nytro(45/136). If i put a Dalton b/b spring in(53/133) i lose some op rpm. I was told that there is a 10+lbs finale rate difference between the 2.

Using Yamaha primary spring & Dalton secondary spring.
I understand your assessment and that's why I want to take baby steps to correct this. It ain't that bad....lol.

 

[snowdust]

lighter twist will lower rpm but also decrease side pressure. I doubt you are actually slipping the primary, but I'm not an expert. I'd go up and down 10 degrees on the secondary and see what belt temps tell you. As for Dalton.. They have a nice chart on their site that is helpful to compare rates.

 

[Doc Harley]

lighter twist will lower rpm but also decrease side pressure. I doubt you are actually slipping the primary, but I'm not an expert. I'd go up and down 10 degrees on the secondary and see what belt temps tell you. As for Dalton.. They have a nice chart on their site that is helpful to compare rates.
View attachment 177668

Ok, I'll try. My fear is, if in fact the belt is restless in the primary, how's it going to like it doing top speed passes?
So I'd rather get some direction now before the fact, then the aftermath. Lol.
I'm not switching to Dalton primary springs. Just wanted to establish direction in doing a primary spring change.
My knee jerk reaction is to take pressure off the spring so the weights can push the sheaths tighter?!?!

 

[snowdust]

Someone else can help you more than me I'm sure. Just remember the primary and secondary fight each other. Making a change to one has an impact on the other. For example... Let's say your secondary is way off and does not open at a reasonable rate. (Stiff spring with high degree wrap) Your RPM's would be high as well. Just loading up the primary will seem like you are going in the right direction as RPM comes down, but belt temps will say otherwise. (or maybe blown belts) Maybe you then decide to lessen the spring in the secondary and now you see RPM also come down but maybe belt temps also come down. Great...Maybe you keep going and now belt temps go back up due to slipping. The marriage between the two is what everyone tries to find. Then you find it and conditions change and now you are slipping due to more traction. lol.

I'd start with someone smarter than me looking at your primary to see if it is in fact slipping. I bet it is not and you can just play with the secondary to find best belt temps.

 

[Doc Harley]

Snowdust,
Slippage is a strong term that doesn't exactly apply. Here are a couple pics.
Pics are after a 6-7 pulls to 800ft
I will try what you suggested and verify temps ty, snowdust

 

[1nc 2000]

This is from the experts and not from me.

Run a common helix and secondary spring like Dalton 35 helix with black orange at 6-2 or 6-3.
Keep adding tip weight until rpms start to drop. If black marks from slippage are still there go to a stiffer primary spring and add more weight until slippage is gone.

 

[Doc Harley]

This is from the experts and not from me.

Run a common helix and secondary spring like Dalton 35 helix with black orange at 6-2 or 6-3.
Keep adding tip weight until rpms start to drop. If black marks from slippage are still there go to a stiffer primary spring and add more weight until slippage is gone.

The last sentence is were I become confused. Why add a stiffer primary spring to fight the weights/arms that are trying to grip the belt? I thought you'd change to a weaker spring, to let the arms/weights squeeze the belt? Idk?
Thanks, Tim
I find this explanation to be the very simple approach I was looking for with just one question above. Ty

 

[1nc 2000]

The last sentence is were I become confused. Why add a stiffer primary spring to fight the weights/arms that are trying to grip the belt? I thought you'd change to a weaker spring, to let the arms/weights squeeze the belt? Idk?
Thanks, Tim

That's what I was told from one of the experts for when the belt is slipping in the primary.

 

[Doc Harley]

That's what I was told from one of the experts for when the belt is slipping in the primary.

Again I think it was a very simplistic awesome response to getting started. And I just wanted to clarification on the question of a weaker / stronger spring does what???