Primary spring...opinions?

[Old Scud-doo]

So, after nothing to do because summer sucks, I am going to be ordering some springs from RCS. Currently running the SLP blue/pink at 140/340. RCS has either a 120/340 or a 140/330, if I had to pick one or the other, which one would you choose and why?

I am kind of leaning towards the 140/340 at the moment. Thanks in advance for your opinions.

 

[0neoldfart]

Personal opinion...

If you are happy with your finish RPM, I would go with the 120/340. Your engagement will be slightly lower, which will make it easier to work with in the trees (less trackspin upon engagement, able to "creep" a bit better).

 

[diamonddave]

If you are happy with your finish RPM, I would go with the 120/340. Your engagement will be slightly lower, which will make it easier to work with in the trees (less trackspin upon engagement, able to "creep" a bit better).

Agree 100%...I would do the same. It makes for a much better tree set-up..

 

[rags319]

Anyone know what stock primary spring rate is.

 

[damx]

140/330

 

[Old Scud-doo]

Stock is 120/340. SLP recommends their 140/340, which is what I am running now.

 

[PaasoRacing]

RMK 600's came stock with 120-340, 800's had 140-330.

 

[Old Scud-doo]

RMK 600's came stock with 120-340, 800's had 140-330.

Really? I remember taking out a Polaris Black/Green spring. I sure thought that was 120/340. Checked it out though with my dealer and Paaso is right.

I ordered the RCS 120/240 secondary and 120/340 primary. I like the current set up and this is as close as I can get to it.

 

[TRS]

This is my opinion on the 120-340 spring. It's rate of 220# creates a sluggish upshift and hinders shift out.
The rate (190) of the 120-310 or 140-330 complements the 800CFI2.
Flyweight profile, helix angles, and secondary springs also play a major role.

The progression to heavier springs, front and back, has led to considerable maintenance to the primary and secondary clutches. The belts of today also had to be designed and constructed to facilitate these new parameters. In relation, the efficiency and the transfer of power to the track suffers.

 

[mountainhorse]

....

 

[PaasoRacing]

This is my opinion on the 120-340 spring. It's rate of 220# creates a sluggish upshift and hinders shift out.
The rate (190) of the 120-310 or 140-330 complements the 800CFI2.
Flyweight profile, helix angles, and secondary springs also play a major role.

The progression to heavier springs, front and back, has led to considerable maintenance to the primary and secondary clutches. The belts of today also had to be designed and constructed to facilitate these new parameters. In relation, the efficiency and the transfer of power to the track suffers.

That is the stock spring for the SBA 800's and these sleds shift really well. It is not uncommon to have them hit 110-112mph stock with the Cobra track.

 

[Teth-Air]

If you are happy with your finish RPM, I would go with the 120/340. Your engagement will be slightly lower, which will make it easier to work with in the trees (less trackspin upon engagement, able to "creep" a bit better).

I completely agree, I run this spring. (same as the 600) but I will consider the 120-310 due to noticing that the Pro RMk does seem to hit a speed wall.

 

[gman086]

So if I'm using washers (thanks again diamonddave!) which raise the rpm's, I would probably be best off using the SBA spring (120-310)? Engagement with the stock 140/340 has always been much harsher than on my Doos!

Thanks,

G

 

[geo]

3 things you need to know about your spring (primary and secondary). Rate, starting pressure, finishing pressure. They are all different parts of tuning.
How much time does your sled spend at full shift (finishing pressure). Not much eh!. Most important # of your spring is rate (because it is the same through the whole shift).

The 600 has a higher rate spring because it has less torque not because it needs a lower engagement. If you raise your spring rate to lower your engagement on your 800 you lost some HP to your track.

TRS pointed towards this. I thought I would expand by reminding people to compare apples to apples.
The reason for so many "opinions" on clutching come out is, to a point, every sled is unique. Elevation and RAD (HP, therefore total primary weight), load (track, gearing, snow you ride, overall mass) means comparing a Switchback to a RMK is a bit out of context. Just like it would be wrong to compare Alaska RMK clutching to Utah RMK clutching.

One size don't fit all on that art, errr part, of your sled.

 

[gman086]

Ah, my assumption was wrong. I see that the SBA and 600 springs are different and edited my last post!

I am thinking though that the SBA spring, with washers (prevents spring binding and raises rpm's), could really be the ticket for the Cascades running F-Bomb's track mod! I'm running Carl's helix so not sure what effect that will have? More progressive than stock from what I understand?

Have FUN!

G MAN

 

[Old Scud-doo]

I am however, not currently running the stock Polaris weights and springs. I am even running a Tied. My setup is/was good with the SLP MTX weights and their blue/pink (140/340) spring. So really my questions was would I do better running the same initial rate, 140, with a slightly lower, 330, finish rate? or a lower initial rate, 120, with the exact same finish rate (340)? I choose to go with the same finish and slightly lower initial. With a number of TIED helixes I figured I could work with the lower initial easier than the opposite considering what I have in my parts bin.

 

[volcano buster]

How do you want the sled to behave differently?

 

[Old Scud-doo]

Honestly, I just want the longer consistantcy that titanium brings. No heat fade, no sacking out. Beginning of season I was hitting 8300ish on new springs. Endo of season about 200 to 300 lower. Not sure if there really is any other benefit to titanium since they really don't weigh much so there really is no rotating mass to worry about.

 

[kanedog]

The rate on a spring is not the first number subtracted from the second number.
The rate is calculated as follows......finish lbs - start lbs divided by the travel of primary clutch. On a Polaris P85 the travel is somewhere around 1.35. I'm too lazy to look it up so don't use 1.35. Confirm the travel of your brand of clutch.
Ex. 120/340 spring...... 340lbs-120lbs=220lbs
220lbs\1.35 inches=162lbs/inch rate. AKA a rate of 162.
At the dealer if you ask for a spring with a rate of 220 lbs(220 rate is crazy high), they will look at you like you have 3 heads. Which, combined with the look they give you when you ask for a simple, easy to find part, they just might fall over and die.
Hope this helps.

 

[PaasoRacing]

The rate on a spring is not the first number subtracted from the second number.
The rate is calculated as follows......finish lbs - start lbs divided by the travel of primary clutch. On a Polaris P85 the travel is somewhere around 1.35. I'm too lazy to look it up so don't use 1.35. Confirm the travel of your brand of clutch.
Ex. 120/340 spring...... 340lbs-120lbs=220lbs
220lbs\1.35 inches=162lbs/inch rate. AKA a rate of 162.
At the dealer if you ask for a spring with a rate of 220 lbs(220 rate is crazy high), they will look at you like you have 3 heads. Which, combined with the look they give you when you ask for a simple, easy to find part, they just might fall over and die.
Hope this helps.

I was wondering when someone was going to mention this... Just so we are clear, according to Polaris these are the rates.
120-340= 168 LBS./INCH
120-310= 145
140-330= 145