Lets all fix this Crappy clutching once and for all

[Rx1M5]

So how far up in the secondary is your belt sitting and how far up the primary is the belt riding up?

Rx1m5

 

[Nikolai]

The belt is barely above the driven sheave, and in the primary is probably within 1/2"-5/8" of the edge now. I know it helped because I gained some MPH too. Can't wait to try the other rollers and dump some pin weight.

 

[tundra]

From your post I am assuming you are talking about off trail riding.

It is nice to see full shift out on the trail for sure, but not on the hill nor when messuring track speed. With a heavy load your clutches should be back shifting ie NOT hitting the top of the primary. If you are 3/4 from the top under heavy load your primary is shifted to far out.

i agree. Its a matter of gearing and power. Higher the belt goes, more HP you need to keep the track spinning at same speed.

Its Very like a mountain bike drive system except the belt does'nt strech. Higher belt goes, closer to 1:1 clutch ratio we are and what we want is to have the strongest gear ratio for optimum clutch efficiency at 1:1.

My old Rx-1 and new apex are the same, belt goes 1/8'' from top when doing high speed on lake in optimum conditions, but mostly she stay 3/4@1'' from top. Its may goes higher a bit, but i guess, we have slipping and Heat.

I was having those very problem with my apex (except belt height) with stock clutching.

I found that Smallers rollers 15mm and light aggresive weight (8BU-00) and a 2 angle helix provide what i wanted the most. Response and Backshift. 44-40 helix and a less stiff spring (grey one). Smaller roller provide more squeezing force and more shifting. 8bu-00 are great because they are fairly light in tips and you can have lot of weight down low and they keep the RPM steady .

i know its an Apex but im getting 45-50 mph track speed (calibrated speedo) with a 162 x 16 x 2.5 and very cold clutch.

4 strokes love a lot of weight in the middle, and yes, torque w/traction = good result.

http://www.youtube.com/watch?v=5FyXghzAP-w
http://www.youtube.com/watch?v=kQtpn1rK ... annel_page

 

[Nikolai]

I ran the 14.5 rollers today with 8FP weights weighing 4 grams less ea. than the loaded 8FS weights. I'm putting the 16.5 rollers and loaded weights back in. With the 14.5 rollers the sled shifted a lot quicker, but it felt like I lost a lot of torque(couldn't pop wheelies like before), backshift was worse, RPM's were inconsistent, and the mid throttle hesitation was a lot more noticeable.

With the 16.5 rollers and loaded 8FS weights the sled feels like a torque monster, will pop and hold wheelies, and has better track speed on the hill. Just my personal findings which seem to go against everyone else, but who knows.

Anyone want to try a set of 14.5 rollers? $60 shipped. Less than 20 miles on them.

 

[Rx1M5]

What are your track speeds with both set ups? I was always led to believe that the best setup is the lightest you can get away with. Using my Heavy hitters and the 14.5 rollers I'm down to 53 grams which is way different than your setup. Interesting. What is the snow like now, setup?

Rx1M5

 

[Nikolai]

Snow was fairly heavy. Track speed was only down a few MPH but it definitely performed worse on the hill. It's really hard to explain, but it felt like the lighter weights and smaller rollers shifted so fast it would just blow through the power band right to peak RPM's and not harness any of the torque. It also wouldn't hold RPM's on the hill(only about 8,400) and it felt like the back shifting was worse(which is was if watching RPM's on the hill).

With the bigger rollers and heavier weights, I can mash the throttle anywhere(deep snow or hard pack) and the sled just gets up and goes. Even in 3-4 ft. of fresh snow it will still hold 8,700 on the hill. I know it seems off that I'm running almost 80 gram weights but it just works. I would have guessed the theory of lighter clutching components are better but riding back to back and going by feel, there is no comparison.

Edit: I am kind of confused as to why the mid throttle hesitation was a lot worse with the smaller rollers.

 

[Rx1M5]

Snow was fairly heavy. It's really hard to explain, but it felt like the lighter weights and smaller rollers shifted so fast it would just blow through the power band right to peak RPM's and not harness any of the torque.

I guess that could make sense. I'd like to ride yours and mine back to back that would be an interesting comparison.

Rx1M5

 

[Nikolai]

How far is Alberta in relation to the AK boarder? I've been looking for an excuse to make a sledding roadtrip to Canada in June.

 

[Srxspec]

The 8FP weights have a more aggressive shift pattern than the 8FS weights. You went with a more aggressive shift pattern and a more aggressive roller as well. I believe you simply had too much weight and that caused a combination of two things. First being overshift because the primary clutch was setup aggressive with the 8FP weights and small rollers and secondly your backshift then suffered as well.

 

[Rx1M5]

How far is Alberta in relation to the AK boarder? I've been looking for an excuse to make a sledding roadtrip to Canada in June.

I mostly ride in Revy area, which has got to be 20 hours from AK. I''m just guessing though.

Rx1M5

 

[ruffryder]

The 8FP weights have a more aggressive shift pattern than the 8FS weights. You went with a more aggressive shift pattern and a more aggressive roller as well. I believe you simply had too much weight and that caused a combination of two things. First being overshift because the primary clutch was setup aggressive with the 8FP weights and small rollers and secondly your backshift then suffered as well.

So the correct change would have been to use much less weight with the 8FP weights?

I tried the 14.5" rollers too. I noticed a similar thing also. I have the adjustable weights you sell and I tried a couple of different combinations during the day. I ended up with 5 washers in the heel, none in the center and one in the tip. I should have probably taken more out of the heel as rpms were not as high as they should be.

I noticed that track speed decreased to about 40 mph. When it would start to trench a little bit, she would slow to 8000 rpms and down to 30 mph.

Definitely worse then my 16.5 mm roller setup.

 

[ruffryder]

Thinking about this more and reading about this more... The amount of mass in a weight is not enough when comparing weights. What is also important, and more important is the shape of the weight. The shape is important because it changes the amount of force that is applied to the roller to move the sheathe inward, vs. trying to move the roller away from the center of the clutch (shifted planes right there)

The type of weights you have, the shape and the amount, require a different helix type to match.

Aggressive shifting primary with an aggressive shifting secondary seems like a problem...

Also, why are people constantly talking about full shift out? Full shift out occurs when you are at max rpm, and the clutches have shifted out 1:1. It is also very close to your top speed. If the top speed of the nytro is around 70 mph, and your tracks speed is around 50 mph in a climb. The only thing that will get you up to a full shift out in a climb is a lot more power, or a significant reduction in gearing..

Been thinking about this clutching issue. Sure is interesting.

 

[akvector]

Nikolai, what did you finally end up with for a final set up last year??

i am putting the timbersled rear in here real soon and plan on dumping the exhaust in the track. I want to get that done and drop to 19 40 before I cange anything in the clutches.

I had Hartman set me up in my vector but I witnessed the same as you did I wound up up going to back to a stock empty weight with the stock spring with the 14.5 rollers.

I would say on hard pack his setup ripped but in the powder I lost power and track speed.

I definately remember my nytro only getting around 8000 rpms in the deep. It needs alot more

 

[Nikolai]

Primary- fully loaded stock weights, GWG spring, 16.5 rollers.

Secondary- pink spring @ 100*, sock helix, 19/40 gearing

9,100+ on the flats and it holds 8,700 on the hill under any snow conditions.

 

[mtdream]

should have my clutch back from Val Simmons tomorrow...

he does a little tweaky to it that allows it to finally shift out fully...talked to quite a few people who did this work on theirs, and it made a HUGE difference...

will post pics when i get it...