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"Proper Clutching" - What is it?

29K views 102 replies 21 participants last post by  Turbo2door 
#1 ·
This is sort of a vague post i suppose, but maybe its not... i don't feel this should be an opinionated answer, this really seems like there should be a definite answer to this question... the specific answer may vary by machine, tune, tires, etc etc.... but there should be definite answer that applies to all scenarios I feel... so lets hear it.... newbies, veterans, weekend warriors, those with clutch problems, those without, clutch gurus ( calling out @Hunterworks @AIRDAM @AftermarketAs @Joey Strub Bmp and any other vendor who markets clutch kits or tuning on this forum ), anyone and everyone.

I've spent the better part of the last year tuning and chasing problems with my clutching... some of you may have seen it on my build thread, some of you have helped (thank you for your time), I've learned a ton about the ins and outs of clutches and they're functionality, but I still by no means consider myself an expert, and all along the way, I don't think I've ever discovered the answer... we see/hear a lot about tuning for a specific RPM, we hear/see about guys "dialing in their clutches", we see problems arise, problems get solved, problems get ignored. We've seen "this cured that" a hundred times... we've heard "Airdam in the solution" countless times, we've seen "Ask Todd" or "Ask Mike"... but the bulk of all the questions come from the search for "Proper Clutching"...because as we've all heard more than anything "You have to have your clutches tuned properly" or "Proper clutching will fix that" or "Proper clutching reduces belt heat,extends belt life, and increases performance".. There's dozens of "clutch kits" out there, all share similarities, some are exactly the same as another, some are unique to themselves, all have ways to "tune" them in the search for proper performance... but there's a different approach from every angle.... so lets try and make some headway with this post.

Is proper clutching purely based on the WOT shift RPM? why do some say it's x RPM and some say its y RPM?

Is a showroom floor machine "properly clutched?

Are upshift, backshift, engagement rpm, helix angle part of "proper clutching" or are those just the tune able aspects for the users specific application?

If my clutch kit says "make a WOT run from a roll at 15-20 mph to 55-60 mph and get you RPM at 8300-8500 RPM" and i do that, is that the only defining factor if my machine is "properly clutched"?

I feel my machine has been "properly clutched" according to instructions 3 times now.... but all 3 times it's had different weights / springs / helixes.... and behaved differently all 3 times....were/are all 3 correct? Or is one correct? Or are none of them actually correct?

There you have it... that's my rant and plea for the answer...

WHAT IS PROPER CLUTCHING?
 
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#4 · (Edited)
Glen Erlandson is EPI, I've read many tech articles from them, good info, but it's all the same conclusion:

"This does this and that does that, and you want this to happen, but not that"

also translated:

"adjust your setup to achieve peak power rpm at WOT, without any belt slippage"

OK, check, got that part figured out.....

So is there 12 (random number) different ways to "properly" tune a clutch?

There's just so many different ways to achieve this... which way is "proper"?

Proper... to me at least, (and that's the big variable in it all... is the opinion of "proper"... but is it open to opinion? shouldn't it be definite? ) would be the setup that generates the most acceptable amount of belt heat (lower is better), while achieving a peak power shiftout rpm, also while having as close to zero belt slippage as possible (less heat, best acceleration, best response, best performance)... so in theory, I've achieved that 3 ways... which one is correct? or are they all? or none? (because i still have a WOT belt heat issue)

Stiffer drive spring, more drive weight, stiffer secondary spring, shallower helix

Middle drive spring, Middle drive weight, middle secondary spring, middle angle helix

Softer drive spring, less drive weight, softer secondary spring, steeper helix

There's an independent reverse relationship between all 4 tune able items that crosses in the middle... are they all correct?

I appreciate the references, but i really want to spark a conversation about it all, it's been talked about from every angle since the first CVT snowmobile ( or before even... but sleds was the first thing I saw a belt driven CVT on ), you'd think, by now, there would be a definite answer to it, i find it so hard to believe that 12 different "clutch kits" with 12 different approaches are all "proper"
 
#5 ·
Re: "Proper Clutching" - What is it?

Here is the thing. There are so many variables it makes it tough.
Some like more primary weight and stiffer secondary springs, others vice versa. Then you have helix angles, which i'm not sure is as important on a SxS as a sled.

I've owned drag sleds, trail sleds, and a couple of SxS's but to be honest, was never a good clutching guy. I could relay what the clutches are doing, what i think they should be doing, then some one that knows what they are doing can pick weights, spring pressures etc.

The one thing i noticed on these SxS's is know one clutches them like a sled. Once i got my stuff clutched like that, all my issues went away. There was a lot wrong on the OEM set up. Misalignment, overshifting, not enough spring pressure for a good backshift etc.

Sent from my SM-G955U using Tapatalk
 
#6 ·
Re: "Proper Clutching" - What is it?

Here is the thing. There are so many variables it makes it tough.
Some like more primary weight and stiffer secondary springs, others vice versa. Then you have helix angles, which i'm not sure is as important on a SxS as a sled.

I've owned drag sleds, trail sleds, and a couple of SxS's but to be honest, was never a good clutching guy. I could relay what the clutches are doing, what i think they should be doing, then some one that knows what they are doing can pick weights, spring pressures etc.

The one thing i noticed on these SxS's is know one clutches them like a sled. Once i got my stuff clutched like that, all my issues went away. There was a lot wrong on the OEM set up. Misalignment, overshifting, not enough spring pressure for a good backshift etc.

Sent from my SM-G955U using Tapatalk
So how are we not clutching them like a sled? Provided misalignment and overshifting are eliminated as mechanical issues, and what is a "good" backshift?
 
#9 ·
This might be the most interesting post I have seen in a long time. Perfect kick off Richard
I have a lot of thoughts and comments I would like to post but I will try to engage the brain before the keyboard!
All I can say at this point is I agree with the OP that the standard settings listed from many vendors and even the testing done by experienced forum members varies greatly
We should see some consistency ...IF IT IS A VERY SIMILAR SET UP
I know the set up weight and all changes everything ...but when you find experienced people that have the same set up and it is ...Far different ...It makes you chase your tail
I look forward to some good input and a long running quality thread
 
#16 ·
But wouldn't it be great to see all of their "opinions" head to head? I feel any vendor who claims they have it figured out should have the willingness, knowledge, and vocabulary to put their methods head to head with anyone else's.. the only (acceptable) aspect holding them back would be proprietary trade secrets, and i can understand that... but I feel the general ideas of it all could be discussed without having to fully reveal any trade secret they may think they have
 
#11 ·
I've clutched everything from stock snowmobiles to 400hp sleds stock utv's to 250hp ones and I've always ran a shallow helix with a lot of spring pressure. The turbos really need a ton of side pressure in the secondary for good belt life. In mine I run the stiffest secondary spring I can find than pick a adjustable weight to adjust your rpm. The primary is the governor of the rpm. My 2017 makes 180rwhp on pump and I have 3000 miles on stock belt.
 
#14 ·
I've clutched everything from stock snowmobiles to 400hp sleds stock utv's to 250hp ones and I've always ran a shallow helix with a lot of spring pressure. The turbos really need a ton of side pressure in the secondary for good belt life. In mine I run the stiffest secondary spring I can find than pick a adjustable weight to adjust your rpm. The primary is the governor of the rpm. My 2017 makes 180rwhp on pump and I have 3000 miles on stock belt.
Does a ton of side pressure purely translate to less belt slippage and less heat produced? Because that's in itself is still the same ideal situation as all models... the Turbo just has more HP to harness, so a stiffer driven spring is required per the application, but the principal remains the same as all CVTs

"adjust your setup to achieve peak power rpm at WOT, without any belt slippage"
 
#12 ·
Asking someone about proper clutching can be like asking someone what their favorite color is. You can have proper clutching for racing, dunes, trail riding, towing and all with varying machines with different HP ratings and modifications where the power band is etc. The answer then is to say it shifts where and how any given person prefers it to shift. You figure out what you want and tune for that.

The different vendors on here may give different recommendations varying the components to achieve the same result. i.e. changing the primary spring can raise or lower engagement rpm but so will changing the fly weights weight.

I liked Alba's descriptions of clutch tuning on page 3. The visual is nice to see what shift pattern I personally prefer. See: https://teamalbaracing.com/files/pdf-installation/UTV/Polaris/clutchweight_4_albaracing.pdf
 

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#13 · (Edited)
Asking someone about proper clutching can be like asking someone what their favorite color is. You can have proper clutching for racing, dunes, trail riding, towing and all with varying machines with different HP ratings and modifications where the power band is etc.
The thing about this is.... it's not that you have different "proper clutching" for each specific scenario.... its that you change the components according to the application to achieve the same desired result. Duning Loads the engine more, so you need less weight to achieve the same shift RPM as a desert racer needs to achieve, he just doesn't tune for being on paddles in deep sand all the time, but then, a fully built race rzr weighs more than the average weekend duner too, so he needs less weight to overcome the added load of a heavier car... but they both want that shift RPM to be at peak power RPM to get the most acceleration and performance form the machine

see what I'm getting at? It's all to achieve the same desired result, I'd even go out on a limb to say the ONLY application specific aspect is engagement RPM, and that definitely has different benefits for each specific application, And that is specifically changed with the installed preload of the primary springs, it is affected slightly by weights, but you don't tune the weights for engagement RPM, you tune the weights for the shift rpm, and the curve to achieve that RPM, the change to engagement is simply a byproduct at that point. Even then, there's only one "desired" shift curve, look at the Alba instructions ( @AlbaNateis someone i forgot to tag, though i know he's not very active these days ) ... "This does this and that does that, and you want this to happen, but not that"... moving and / or adding/subtracting weights is simply a tool to achieve the same shift curve.... which is essentially as steep of a line as possible to peak power RPM, Alba does show a subtle difference in the "ideal shift pattern" between the two applications they show a graph for, but i'd still be curious as to their reasoning for wanting RPM to taper off slightly for a drag racing application, which in itself is a very specific niche.

Now a guy that absolutely never uses WOT.... does it even matter to him if his shift rpm is correct? In practicality, no, because he never uses peak power. However in theory, it does matter, and it's the same guidelines he'd be given for tuning his clutch.
 
#18 ·
Right? are good and bad relative terms in the matter? or is it more "incorrect" and "correct"...and how does that vary per specific application?

And when you get into backshift you've (finally) moved out of the basic "adjust your setup to achieve peak power rpm at WOT, without any belt slippage" instruction (or have you?)

Backshift is still one aspect I'm trying to fully grasp...

(I apologize for not multi-quoting these posts guys, my replies are coming as different comments spark different thoughts in my head)
 
#21 ·
I will throw my 2 cents in later today, but there is no one answer, the main thing is what are you doing with it that determines how you set it up and too many "clutch gurus" leave out that important question.
This. For myself, I have two different riding styles. One with the wife, one without.
If all I did was ride with the wife, chances are I could have gotten away with the stock clutching , even though I destroyed a couple of belts by having the top cogs stripped from contact with the clutch cover (an easy fix)
Where my issues were when I was riding with the guys. That style was very aggressive, lots of WFO for extended periods of time. That is when I had to dive into the clutch set up.
 
#28 ·
Here is my current clutch set up, for the discussion. My machine is a '16 XP1K two seater. The machine is stock except the cat is gutted out of the OEM muffler and I have a stage 1 tune from Aftermarket Assassins. I ride mostly sea level.
I've got an aluminum roof, front and rear bumper , light bar and carry about 50lbs of gear. My target rpm is 8600.
Primary is a machined OEM (P85)
Weights are 51.2 grms
Primary spring is 65/245 plus a shim (needed an extra 50rpm)
also have a spacer to keep the primary from overshifting.

Secondary is an STM with larger cooling fins
secondary spring is 198/322
Helix is 30/60

This set up gets me to 8600 almost instantly. Belt temps average 180-190 with aggressive riding and will max out at 205-207 on long (multiple mile) runs at 60 plus mph. Top speed on a hard pack road was 81mph, in sandy trails 74mph It took a while though to get those. Generally it will hit 65-70 pretty quickly.
 
#29 ·
This set up gets me to 8600 almost instantly. Belt temps average 180-190 with aggressive riding and will max out at 205-207 on long (multiple mile) runs at 60 plus mph. Top speed on a hard pack road was 81mph, in sandy trails 74mph It took a while though to get those. Generally it will hit 65-70 pretty quickly.



So.... you tuned for a specific peak RPM with as little belt slip and belt heat as possible, an achieved it very well?




-Give it a second... it had to go to space and back first ( Sent from the lifeline that is my iPhone XS Max )
 
#31 ·
Ok here is the deal and this is a rather deep subject and I will try not to make this boring

When a vehicle is new we assume polaris has calibrated the clutch correctly for a stock vehicle doing a mixture of riding from slow to fast etc. BTW sometimes they do a good job some times they suck at it.


So all kits no matter the brand are simply trying to put shift phase rpm where it belongs which is where the engine makes power at after you did something like put bigger tires, changed elevation or riding in sand.

All of those are a load and the kits allow you to put it back if you will to what it was factory again assuming they got it right.

This is for a stock engine.

Reasons to put a kit in, you changed tires, you changed elevations where you dropped rpm due to less power etc

The kit makers just do it different ways, some kits suck some do not.

Then to throw a monkey wrench in there what kind of riding are you doing?

Slow rider no matter whether stock or larger tires need belt grip not performance so we normally say keep them stock or if you have a kit then set the kit for stock tires, this just makes the set up in the kit heavier so you have belt grip. Heavier weights grab faster and more clamping force.

One and off the throttle guys, they need the rpm where the engine makes power so as I say just follow our kit instructions that is what it assumes youare doing. Again if you changed tires or elevation then you are out of whack and need a kit to put it back

Duning, that needs more rpm than normal because the sand is going to drag you down so you need it higher before you hit the dune etc.

But as you mentioned they are all trying to get to the same thing, well more or less except for the slow rider he just wants belt grip.

At the end of the day no matter where you decide to get your clutching done if they do not ask you what you are doing with the machine and what tires then move on because they just want your money or have no idea what they are doing.

I hope I answered your questions and if not then ask a specific one and I will try and answer.

Todd
 
#34 ·
Ok here is the deal and this is a rather deep subject and I will try not to make this boring



When a vehicle is new we assume polaris has calibrated the clutch correctly for a stock vehicle doing a mixture of riding from slow to fast etc. BTW sometimes they do a good job some times they suck at it.





So all kits no matter the brand are simply trying to put shift phase rpm where it belongs which is where the engine makes power at after you did something like put bigger tires, changed elevation or riding in sand.



All of those are a load and the kits allow you to put it back if you will to what it was factory again assuming they got it right.



This is for a stock engine.



Reasons to put a kit in, you changed tires, you changed elevations where you dropped rpm due to less power etc



The kit makers just do it different ways, some kits suck some do not.



Then to throw a monkey wrench in there what kind of riding are you doing?



Slow rider no matter whether stock or larger tires need belt grip not performance so we normally say keep them stock or if you have a kit then set the kit for stock tires, this just makes the set up in the kit heavier so you have belt grip. Heavier weights grab faster and more clamping force.



One and off the throttle guys, they need the rpm where the engine makes power so as I say just follow our kit instructions that is what it assumes youare doing. Again if you changed tires or elevation then you are out of whack and need a kit to put it back



Duning, that needs more rpm than normal because the sand is going to drag you down so you need it higher before you hit the dune etc.



But as you mentioned they are all trying to get to the same thing, well more or less except for the slow rider he just wants belt grip.



At the end of the day no matter where you decide to get your clutching done if they do not ask you what you are doing with the machine and what tires then move on because they just want your money or have no idea what they are doing.



I hope I answered your questions and if not then ask a specific one and I will try and answer.



Todd


I don’t disagree with anything you said Todd, but it all just reaffirms that tuning for a peak RPM with the least belt slip and belt heat is “proper”.... but how can there be so many different combinations of weight type, spring rate, helix angle, etc.... for the exact same machine to achieve the same goal... I feel that there’s give and take with all the differences, but what is the preferred give, or take?

Say the machine doesn’t change at all, atmosphere doesn’t change at all, the ONLY thing we’re changing is from clutch kit A to clutch kit B....A used softer springs, lighter weights, and a steeper helix...B uses stiffer springs, heavier weights, and a more shallow helix.... but both achieve target RPM and Belt grab.... are both “proper”? Are we down to the small(relative term) details at that point? Like backshift rate, engagement RPM, and throttle response? And if so... wouldn’t the quicker backshift, and quicker throttle response prevail for the better? ( I’m leaving engagement RPM as an “option”, because I think that can be adjusted without effecting the rest, provided it’s done properly )


-Give it a second... it had to go to space and back first ( Sent from the lifeline that is my iPhone XS Max )
 
#37 ·
Hi all....I have copied a statement from Adam at Airdam clutches. This thread was titled Low Engine RPM thread on June 27th. 2019. I think this shows that a mathematical approach can be taken into account and to the OP's point ...the variables should not be massively different.

ideally, with a proper working machine, water temps good, good fuel, no mechanical issues, i tell customers when relaying RPM info to me to check for clutch calibrations, get the water temps to 175 and make a run or two, 10mph roll, roll hard into the throttle and make a full throttle accelration run from 10mph to 70mph. checking the RPM every 10mph and by knowing this info i can tell you a lot. knowing the spring rates, and weight layout, i can tell you within a hundred RPM what you should be running. the clutch is actually a very simple math algorithm that i have figured out. there is a certain amount of spring rate in the primary, and a certain amount of reciprocating mass in the weights, those weights with their certain mass, will overcome that springs tension at a certain RPM based on the amount of power you apply.

example;
200lb spring, 64 gram weights, 150hp, would equal 8150 RPM
200lb spring, 65 gram weights, 150hp, would equal 8000 RPM
200lb spring, 66 gram weights. 150hp, would equal 7850 RPM

so when someone calls me, and says, i got this spring, and these weights, and im only pulling 6900RPM, first, knowing the springs tension, and weights mass, you can flip the algorithm to calculate HP, you need three variables and you can calculate the fourth one. if you tell me what HP you make on a dyno, and what RPM you are running, i can tell you the weights mass if i know the springs rate.
 
#39 ·
Yesterday I ordered Adams clutch kit ....weights , primary spring, secondary spring , and his primary cover. I did not get his primary or secondary. I am currently running the AA stage 3 and I am very curious to try the Airdam set up. I will report back when I have some details
 
#45 ·
I definitely was hoping it would go much farther.... only one "clutch guru" decided to participate tho, that''s kind of sad really.

That, and I don't think that many people care to have a technical discussion anymore.. too much "tell me what to run, and that's all i care about" going on these days...nobody wants to learn or know the "why"

I did a lot of thinking about clutch functionality yesterday.. I started typing up a LONG post...(that may or may not even be useful lol) but I'm out of time at the moment... I have it saved in a draft and will continue working on it
 
#47 ·
To the Op ...I understand your frustration but dont give up . The first few pages got the attention of some top members and it was a good conversation. I think post's like this need time to develop ,and for many myself included they are a little intimidating ...I can have a conversation verbally much better then I type. I have wanted to post more ..I do have quite a bit of practical experience ...and have tested and spent money on more than I care to admit ....I wont go on about all the rzr's ...or the mods I have done good and bad .But most members have only joined the forum recently or in the last few years ..sometimes the level of expertise / members posting is faster and more detailed ..and is a little intimidating ...so they watch and learn ...dont stop this is what this forum is all about ..I will try to help keep it at the top of active ...and at some point more vendors will have to chime in.

Good stuff!
 
#48 ·
I did not read the entire thread. Olav’s book is great. My .02 is that the best clutch setup is the one the runs the coolest while not letting the belt slip. I know that’s obvious but it’s that simple. If your clutches are running too hot, then your clutching is off, and if your belt is slipping(which creates heat) then you know your clutching is also off.

The rest is really personal preference. Engagement RPM, backshift, smooth upshift or hard hitting off the line ect ect. One thing I learned a long time ago with sleds is to change 1 thing at a time and keep notes. Whether it’s changing weights, grinding profiles, swapping helix angle or changing springs.

I will say this, I honestly think in most cases, aftermarket clutch kits lose performance. This is not because of the kit itself, but people are too lazy to fine tune. Example, pulling over mid ride to take weight out of the heel and add more weight to the tip(on an adjustable flyweight). I’ve ridden a lot of terrible clutching on both sxs’s and sleds. If you’re not the kind of person willing to put in the time, then leave factory clutching in it.
 
#50 ·
I did not read the entire thread. Olav’s book is great. My .02 is that the best clutch setup is the one the runs the coolest while not letting the belt slip. I know that’s obvious but it’s that simple. If your clutches are running too hot, then your clutching is off, and if your belt is slipping(which creates heat) then you know your clutching is also off.

The rest is really personal preference. Engagement RPM, backshift, smooth upshift or hard hitting off the line ect ect. One thing I learned a long time ago with sleds is to change 1 thing at a time and keep notes. Whether it’s changing weights, grinding profiles, swapping helix angle or changing springs.

I will say this, I honestly think in most cases, aftermarket clutch kits lose performance. This is not because of the kit itself, but people are too lazy to fine tune. Example, pulling over mid ride to take weight out of the heel and add more weight to the tip(on an adjustable flyweight). I’ve ridden a lot of terrible clutching on both sxs’s and sleds. If you’re not the kind of person willing to put in the time, then leave factory clutching in it.
Couldn't agree more. And yes, for one to get anything perfected , suspension, engine mods, clutching , etc. they must take the time to do it. Note things, make a change (not changes) , reference notes , etc.

Many , many, years ago I wanted the fastest trail sled I could have. Light, fast , reliable. I bought a '96 680 Ultra SP. I brought it home and completely dismantled it. Sent the motor out, added a light weight suspension, added titanium wherever I could, punched the motor out to 800, had pipes made , dyno time, the spent an entire season dialing the suspension, clutching and motor in. That resulted in a 179hp , efficient (on a backpack trip I was using less fuel than a stock Indy 500), fast (would walk all over MachZ's and the Tcats) that lasted me 8800 miles.

At that time I found another one new in a crate, swapped all the parts to the new one, basically through it together in a weekend and went riding. That ended up being the worst sled I ever had. It just never ran right. Looking back, there were a couple of things I overlooked which effected everything.
 
#52 ·
I have some that i took when troubleshooting some things a while back, I never uploaded them to where i can post tho, I'll see if i can find them later

I have seen a few other from time to time they, they do exist, it's cool to watch once or twice, but really hard to get any absolute information from (unless something is majorly wrong)
 
#54 ·
It's VERY hard to tell any difference without a lot of time and effort being put in for consistent testing and references... not to mention everything happens so fast, and is spinning so fast, you just see it happen, can't tell much difference in what is actually happening.

Here's one of mine I was able to track down real quick just to give you an idea of it all:

 
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