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Discussion Starter · #1 ·
if the numbers go up more or less performance? help me depict them lol. uh what does 170# preload and 300# shift, or 155#preload and 285# shift.
 

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The numbers have units of pounds per inch. That means a 170-300 needs 170 pounds of force to compress the spring the first inch, and another 170 pounds to compress it another inch (for a total of 2 inches compressed).
The first number is the preload rate, the second number is the full shift out.
The higher the number, the higher the RPMs the motor turns.

Say you have the 170-300 spring, and your engagement speed is 3500 RPMs, and your max RPM is 8000.

Now if you put in a 155-300 spring, it will only take 155 pounds to compress the spring the first inch. This means it is easier for the motor to make the clutch engage. For example, the engagement speed will drop down to 3000 RPM, but the max RPM stays at 8000.

But if you instead put in a 170-285 spring, then it will be easier for the motor to spin the clutch at high RPM. In this case, the motor will spin faster than it needs to, so the max RPM would be 8100, but the engagement speed will still be 3500 RPM.

This is just a scenario to show you what the numbers mean, these aren't actual results of using these springs. Also, this scenario is correct if all other components remain constant (weights, secondary spring, helix).
 

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Polaris_Parts_MN said:
The numbers have units of pounds per inch. That means a 170-300 needs 170 pounds of force to compress the spring the first inch, and another 170 pounds to compress it another inch (for a total of 2 inches compressed).
The first number is the preload rate, the second number is the full shift out.
The higher the number, the higher the RPMs the motor turns.

Say you have the 170-300 spring, and your engagement speed is 3500 RPMs, and your max RPM is 8000.

Now if you put in a 155-300 spring, it will only take 155 pounds to compress the spring the first inch. This means it is easier for the motor to make the clutch engage. For example, the engagement speed will drop down to 3000 RPM, but the max RPM stays at 8000.

But if you instead put in a 170-285 spring, then it will be easier for the motor to spin the clutch at high RPM. In this case, the motor will spin faster than it needs to, so the max RPM would be 8100, but the engagement speed will still be 3500 RPM.

This is just a scenario to show you what the numbers mean, these aren't actual results of using these springs. Also, this scenario is correct if all other components remain constant (weights, secondary spring, helix).
I think he meant the 170-285 spring will make the sled rev lower at max rpm.The springs are used in combination with different weight profiles to tailor the shift curve for best performance and keep your sled running at the peak RPM where it makes max HP.The first number effects engagement RPM,higher the number the higher the RPM the sled starts to move.
 

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whoops, my mistake. a 170-285 would make the max RPM drop below 8000.
 

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Discussion Starter · #5 ·
well in the hpe book it says higher engagement springs. and my sled right now engages about 4500 rpm. what could i do to my stock clutch to gain a little and still stay reliable?
 

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You know.. I bought Olan Eane (sp) book on clutches, and it has enlighted me to no end. Plus the "carb" book too..
 

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Olav Aaen (founder of AAEN performance). Also have the clutch tuning handbook, it's a very good read. Tells you the basics plus all the technical stuff. I plan on getting the carb tuning handbook sometime too.
 

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Discussion Starter · #8 ·
so what can i do to make it a little snappier without losing too much top end and still have a reliable clutch?
 

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What are the rates of the stock spring? Whatever it is, find a spring that has a higher engagement rate but the same finish rate. This will give you a hard launch but still keep your max RPM in the powerband.
 

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Discussion Starter · #10 ·
this might seem like a dumb question but i wont know for sure til asked, can i find that on a spec search for my sled? it engages at about 4500 and max is 9000. that is no help i dont think but just saying.
 
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