What's better for RPM heavier primary or lighter weights?

[AaronBND]

Whats better for RPM heavier primary or lighter weights? UPDATE

I need about 200 more rpm's hill climbing. I now have the SLP green/yellow which is a 160/310 (a little to high of engagement for my liking too) and MTX 77g weights with 2oz in the tip and 2oz in the heel. The problem is my primary is getting hotter than my secondary clutch, so I'm not sure I want to drop much weight to keep the squeeze on the belt. Is this the right thinking? Should I go to like the Speedwerx black (140/335) or the white (125/340)? Also, how much would 25-30lbs on top get me rpm wise? Thanks!

Aaron

 

[skidooboy]

your thinking is right. both of your spring choices will give you both of what you are looking for.... lower engagement, and more spring to overcome the weights to give you more rpms. springs are cheap, buy em both give em a try, both may be used at one time or another due to snow conditions.

there are 2 trains of thought on clutching, lighter weights and lighter springs, heavier weights and heavier springs. both will get you where you need to be rpmwise but, the sleds track speed will tell you which team you need to be on, so to speak.

the rest is trial and error, a good note book helps alot. you can duplicate set ups year to year. or get back to a known rpm if you get "lost" during a test.

good luck, ski

 

[Frostbite]

Welcome to my world Aaron! This is what always seems to happen to me.

There a bunch of things you can do.

You can drop the finish angle on your helix a degree or two as one option.

Drill out the rivets in the tips of the clutch weights. It sounds like that might make things just right.

You can go to a stiffer secondary spring that won't allow your secondary to shift all the way out as fast or at all. I have several much stronger secondary springs I have tried. Some fit nicely into the helix others don't, I seem to remember a green and white spring I really liked.

Or you can go to a higher total force primary spring. I usually end up playing with all the options to get there. I follow this guidnce, the more clutch weight you can throw at the motor and still reach your shift speed, the more power you're going to eak out of the motor. For that reason I always end up with the stiffest total force springs. Right now, I have a Speedwerx H5 alloy Red/white spring in the primary. SLP has a 140/340 Black/pink if I remember correctly and someone (Goodwin if I recall) has a 140/360 primary spring. I like the 120/340s the best so far.

Good luck, let us know how it goes.

 

[m7ryder]

This will be a thread for a lot of people to keep their eye and learn some valuable clutching info

 

[AaronBND]

Welcome to my world Aaron! This is what always seems to happen to me.

There a bunch of things you can do.

You can drop the finish angle on your helix a degree or two as one option.

Drill out the rivets in the tips of the clutch weights. It sounds like that might make things just right.

You can go to a stiffer secondary spring that won't allow your secondary to shift all the way out as fast or at all. I have several much stronger secondary springs I have tried. Some fit nicely into the helix others don't, I seem to remember a green and white spring I really liked. Can you really have your cake and eat it too?

Or you can go to a higher total force primary spring. I usually end up playing with all the options to get there. I follow this guidnce, the more clutch weight you can throw at the motor and still reach your shift speed, the more power you're going to eak out of the motor. For that reason I always end up with the stiffest total force springs. Right now, I have a Speedwerx H5 alloy Red/white spring in the primary. SLP has a 140/340 Black/pink if I remember correctly and someone (Goodwin if I recall) has a 140/360 primary spring. I like the 120/340s the best so far.

Good luck, let us know how it goes.

I am thinking the same as your advice Lee. I think I will try that H5 spring you are running before I try dropping weight. What rpm increase will I see going from a 310 up to a 340? Also, by going with the stiffer spring rate, is it harder on the spider and rollers? It seems like it would be a give-take thing as being harder on the primary parts maybe?

Aaron

 

[Destroyer]

I'm using the SLP blue pink right now (that's the 140/340). It gave me about 100-150 rpm over the 285 and 290 finishes of the cat springs. The only thing I'm unsure of is that it seems pretty thick. The cat black orange failed from spring bind, so how is the thicker slp spring going to hold up? But I'm happy enough with it.

I want to run more weight...I'm using 70's right now at 0-3000' in my 2010 with a 44/40 helix and my WOT rpm's are inconsistant in loose snow. On/off Mid range it works good. I Might just try a straight 36 or, 38, or a 40/38, or a 40/36 and hopefully be able to add some weight. I would really like to find a helix that will work good for high and low elevation.

What are you guys running for helix's

 

[WyoBoy1000]

Your thinking may be right and may not be, If your primary is slipping and you want more squeeze. Well if you get the squeeze what will happen is it will try and upshift the secondary which in turn will lower rpm, or just dropping weight and all the sudden it hooks up it might drop another 100rpm. dropping weight is the same thing as a stiffer spring. but heavier weight and stiffer springs give a better backshift at higher speeds. Although I've seen some heavy spring cause more damage. I would pull the 2g in the heal and see what happens, I also would like to try the sw R/W. I would also like to have a helix that started at 42* and progressively went to a 36* about half way (or be in a 36* or less at 45mph and up) and then from there finished at a 34*, triple angle helix.

 

[AaronBND]

Well, I went ahead and ordered what appears to be the Red/White from Speedwerx. It actually only had listed a "white" spring that is a 125/340. I hope this is the right one. It didn't list the Red/White, but it is a 125/340 that I got. Got it 2nd day air so it should be here Wednesday to try. I just hope it isn't to hard on the rollers and spider over time.

Aaron

 

[winter brew]

If you are getting RPM on the flats and dropping the 200 RPM on climbs, I would look harder at helix angle and/or secondary spring. Also, do you have a "straight shift"? or does the RPM over/under rev at any point from engagement to full speed?

 

[CO 2.0]

Out of all the springs I've tried thus far the Speedwerx 125/340 has had the best of both worlds for me. Best top end and almost the best bottom end of any spring I've tried. I also run the thunderstruck washers on each side of the spring. The SLP springs I had issues with binding in the primary spring cups. Didn't feel like taking material out to get them to work. SW seems like the same thickness as the SLP springs, but seem a bit higher quality metals used. Haven't had any spring bind with the SW.

Cat black/orange
Cat Orange/black
Cat yellow/white
SLP blue/pink
SLP black/pink
SW Red/white

 

[Arctic Thunder]

One thing you might want to do is test each spring prior to installing.

You are making a pretty good jump in finish rate so I am sure you will see it.

But what I have found is if you think you have a 310 finish rate spring now, and want to try a 330 or a 340 you should test the 310 and see what it really is, then test the new springs and see.

We have pulled new springs out and found some reasonable differences. Enough to make you scratch your head and say "I thought 30lbs would do more than that" then to test them and find out I was only 10lbs different.

Something to check if you have them apart.

Thunder

 

[killerrf]

so would the best thing to do is start with like a cat yellow/white spring that is stock in most sleds then add weight till where it starts to load the motor to the max then use an aftermarket spring to just fine tune the wot rpm the best then... if you need to jump over that 300 lbs mark?

when i look at whether you use lighter weights and lighter spring vs heavier weights and heavier spring.... as long as you seem to be loading the motor the most keeping it within the proper rpm range it shouldnt matter??? but like wyoboy says heavier combo primary backshifts better at higher speeds so.... this clutching gets confusing sometimes.

 

[Frostbite]

Wow, this turned out to be a good thread.

Yes, your helix angle is HUGE. I am trying to pull a 45/37 degree helix and scratching and clawing to pull 8,200 RPM out of the motor. SLP recommends a 44/36 but, I thought that since I ride below 8,000 feet and and I weigh well under 200 lbs (170) that I should be able to pull one more degree of finish angle on my helix. Maybe so, maybe no?

Also, make sure your helix is a dual angle helix and not a progressive angle helix. I love the way the progressives work much better on the trail but, while climbing you never know exactly what angle you are at on the helix with a progressive rate helix. It changes depending on snow conditions, incline, etc. With a straight 36 degree angle helix you always know what angle of helix you are on and it eliminates one clutching equation. The dual angle jsut have a short starting angle (44 degree) and then for the vast majority of the helix it is 36 degrees. So you get the benefit of a quicker start and the stability of a straight angle helix.

Here's one from a while back that talks about the same topic.

http://www.snowestonline.com/forum/showthread.php?t=178169

 

[Alberta Sledder]

On advice from Brent Linderman, I have 73g weights, cpc purple/white spring (175/305), stock secondary spring and 44/34 dalton helix on a ported, cut head and jaws twined 2008 m8.

This setup is very similiar to a previous post.

I also had my doubts about playing with my semi-stock configuration and adjusting to this final combination. Now my m8 is sick and really fun to ride!!!!

What I learned:

1. Using a heavier spring that increases engagement does often require heavier weights
2. The right spring/weight combination even though it is heavier does not necessarily harm/affect throttle response
3. Really like the two angle 44/34 helix- seems to have the best of both low end and high end. Other untested helixes may prove better in the future.

Great thread guys....still learning!

 

[Desperado]

Good thread, I'll keep an eye on it, I've given up trying to fix my loosing RPM by fixing or adjusting the primary springs and weights. I've also given up trying different springs and helixes for the secondary. I'm going back to stock on the primary and I just ordered an RKT secondary. This will be my last attempt to fix this problem. Personally I do believe this RPM and loss of track speed lies in the secondary not the primary. I will post results once I get the kit. FYI from all the money I spend on springs, weights, and helixes I could have already bought either an RKT or CPC conversion.

 

[Flatbed]

It's been posted on this forum before numerous times that engine Rpm's are regulated with the primary clutch. Find the spring and weight combo that gives the rpms you are after and leave the primary alone for now. The secondary regulates your shifting in and out. It's best to put in the heaviest weights that your motor can handle. Artic cat secondarys are somewhat of a nightmare. Some of them work with the stock setup and some don't. I had one that did not. I have an 09 M8 LE and could not get my rpms up no matter what I did to the primary. That tells me right off the secondary was not shifting right to help out the drive cl. I tore the secondary apart and it was in great shape. Put it back on the sled, same thing. Put in a new sec. spring. Same thing. Ordered a RKT sec. kit, put it on the sled, night and day difference. My R's are up and and I can change my shift points where I want. So what I am saying if your M8 is not pulling like it should it is not your primary, you have a faulty secondary. I ride at 8 to 10,000 feet. My set up is SLP black/pink with 70 cat weights and RKT sec. with the helix and spring he recomends for my elevation. I have a CPC torsional on my M7 and it works great also. Hope this helps out.

 

[WyoBoy1000]

See if this makes sense.
When it comes to clutching and helix angles on the M sleds you have to remember because of the DD the secondary is load sensing so hp doesn't make as much difference. So rather than saying you should be able to pull more its more on the lines of how fast can you spin the track and someone like me at 6' 6" and 210lbs can get more transpher putting more load on the track, thats the reason for m8 and m1000's running the same helix. Then move to the rpm peak and drop. What it feels like to me is the secondary spring is stiff and on high hp selds when you punch it the primary engages and forces the secondary to open but has so much pop that it sling shots the secondary into an over shift, with the secondary in to high of gear (shifted out to far) it tries to backshift but with the weights and pull of the primary it wont let go for the secondary to backshift in turn dropping rpm. So how do you get the secondary to not over react, either less weight in the primary or a lesser angle on the helix (you could increase spring pressure but I think the orange secondary spring is already to stiff). I also think the slp 44/36 is to steep on the bottom for tight low speed riding, I think a 42 or 40 start will give a little better on off throttle response and slow down the sling shot effect. Being my weight, I think after about 45mph if I was in a 36* or less down to 34* would work the best. the steeper starting angle is a great out of the whole method, but a stock m8 will beat a mod m1000 because the m1000 can't find traction, so you don't really need it. (the sling shot is also going to be increased with heaver weights and springs in the primary)

Now with that said anyone running a shift assist it is going to double the sling shot effect, thus the reason I think the Shift assist can be a negative, with the washers it gives the clutch a more consistent load sensing on the top and bottom (less chance of a sling shot because of friction), but in mid shift and downshift I think the shift assist seems to be better as it reacts quicker. I also think when the shift assist is at max track speed it helps create a downshift load with the help of the orange spring that it wants to backshift all the time rather than hold speed or upshift. So this idea has me looking at a rkt secondary pretty hard, it could eliminate the problem of the stiff spring and have better shifting all together and the ability to adjust and set it up for rider style. Or have a helix made to use the old m7 style adjuster for the spring tension - but that could still cause shifting to be better or worse top and bottom.

 

[AaronBND]

I have to agree with your thinking WyoBoy. I can honestly say that since I bought the RKT setup a week ago for the first time, it has definitely impressed me. Up until the RKT I have on now, I had the best luck out of all my different combination's with the CPC torsional setup I was running a couple years ago. I think they just flat out work better after now having the RKT one too. It starts getting really mind-boggling after a while, because of all the different theories and opinions. I think a lot of the clutching answers and set up boils down to what you like. Do you like the out of the hole, light front end, wheelie feel, or do you not care so much about that and just want to get highest on the hill in deep powder. There are so many variables out there for you to choose from and I don't feel you can get the best of both worlds.

Aaron

 

[AaronBND]

I installed the red/white spring from Speedwerx and see absolutely no difference on the top end. Still only seeing 7500 climbing. What do I need to do, just start dropping rivets weight in the MTX's? I do however really like the low engagement of the 125 bottom side of the new spring. I am thinking If I need to drop weight though, I might as well go back to the stock yellow/white. The stiffer spring is making no difference on the top rpm's anyways and it has to be harder on the rollers and spiders being a 340 finish right?

Aaron

 

[WyoBoy1000]

You can't go back to the stock spring because the 77g mtx's are setup for a stiffer spring. I would pull the assist. wouldn't be suprized if you jumped to 7800rpm. But watch track speed from one to the other and let us know. The SLP pipe still pulls really well at 7500. If there is no improvement from pulling the assist then I would drop weight, prob pull the 2g from the heel.