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Discussion Starter #1 (Edited)
Shift RPM Explained Deeper


The following is a tech article that is really a conversation I have several times a day on the phone and thought I would just put it in text for anyone to read.

What is shift RPM?

Should be called shift phase RPM really and it is the RPM the engine is running during the shift phase of the clutch which is basically from the time you start moving until the belt fully shifts out or moves as far as it can on the clutches.

The purpose of the CVT clutch system is to try and maintain a particular RPM during this phase where the engine makes most of it's power for maximum acceleration. The tachs on a RZR are very slow responding, you are at shift speed a whole lot longer than your tach tells you that you are due to the slow response. I usually tell people to get the belt warm, get rolling and floor it until top speed while watching the tach and it usually will level out around 45-60 mph depending on which RZR and the tach will either slow way down or actually stop then once the belt is fully shifted out past that point the RPM will tick on up to whatever top speed RPM is which is basically the engine speed that the vehicle is capable of. People with bigger tires, added weight etc drag down speed and rpm at top speed due to load. We can adjust shift speed with the clutch or clutch kits such as the Dalton kit we sell to get the RPM where we need it for maximum performance.

Also there is no shift feel, you are not looking for a shift or feel a shift, it is simply a term used to describe what is going on. Your CVT is shifting from low ratio (idling) to high ratio (fully shifted out) the whole time. The engine will sound like it is changing rpm too during shift phase but what you are really hearing is a load change on the engine. Easy to prove by running one on a dyno, during shift phase the graph has RPM flat.

Ok now we know what it is, so what about it?

A black and white answer is there is just one shift speed for any particular vehicle we need to shoot for when setting our clutch up. But that is really just for a group of people who I say use their RZR for it's intended purpose which is fast trail riding, on and off the throttle. Let's use the XP 1000 as an example. For this kind of rider we would set the clutch up for the engine to have a shift RPM of around 8300 RPM and it will work well.

But what if you are a rock crawler? Slow technical rider? Or even a duner? Well 8300 may not work for you very well. I like to say that when you are trying to clutch for maximum performance for whatever you are doing then clutching gets specific and requires you to adjust accordingly. A slow rider, rock crawler, mud guy is more concerned about belt grip more than anything and rarely gets into actual shift speed because he does not floor it and haul butt that much. So, I usually tell that guy to set his XP 1000 to a shift rpm of about 8100 and he does that by adding a bit more weight into the flyweights. What this does for him is makes his clutch engage sooner and with more clamping force on the belt. However, this heavier set up would not be as good as the higher shift rpm for some fast trail riding but it would do pretty good in some short drag races. This group of riders need to know that a RZR of any kind normally does not do well going slow. The larger and more powerful machines such as the XP 1000 have a harder time going slow due to weight of the machine, the powerful engine and the fact the clutch has to come in and squeeze the belt to get you moving add up to a decent amount of potential belt issues. It also does not help that the majority of this group normally has larger tires to accomplish the style of riding they do for clearance.

Duners, well these guys need more RPM due to the added load of the sand and the climbing up the dunes and it dragging them back down. Again using the XP 1000 as an example I would say a shift RPM of around 8500 RPM would work for these guys.

If a duner who set his clutch up to run in the dunes took his RZR rock crawling the most likely thing that would happen is a good bit of belt slippage due to the lighter weights.

I want to add something here that is not so much about shift speed as it is about people trying to adjust top speed rpm with a clutch adjustment. First, don't do this as this, it is not how it is done. Can you adjust rpm at top speed with clutching yes but you should not, you should set shift speed with the clutch and what you get what you get at top speed.

Example: A XP1000 owner who got his ECU flashed and raised his rev limiter and lets say it was at 9500 instead of 8500 and wants to hit it or run near it. Sure he can take weight out of the flyweights to get there but how is it doing it? He is getting the flyweights so light that the primary clutch can no longer close all the way and he just screwed up shift RPM which in turn just screwed up his acceleration and less belt grip at slow speeds. It will have less acceleration now but yes he is at the new higher rpm at wide open but it is wrong. Does he actually drive at those speeds and RPM much? No and regardless even if he does, he could run the same top speed or maybe faster with lower rpm by not doing that. My point is, set shift RPM where it should be and top speed RPM will take care of itself, it will be whatever you have enough power to pull you to. I use a 5 speed car, once you shift into 5th gear you are a the mercy of how much power you have to speed on up. In a five speed car, would you push in on the clutch and let it slip a bit to make rpm go up while at top speed? Would you do this just so you can see the tach go up?

Who benefits the most from a clutch kit? The duner and the fast trail rider more so because belt slippage is not a concern and they want performance. Can a slow rider benefit? Yes of course but not the same way the other two can.

Here at Hunterworks we don't just give a canned response to what you have. I listen and hear your application then help you figure out what we need to do that best then tell you the limitations of that set up when used for anything else such as mentioned trying to go duning with a rock crawler set up.

Hope this has helped clear up shift rpm a little more

Got any questions give me a call

Todd
 

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Todd, that's about the best explanation I've ever seen. Thank you for that! I will contact you soon for a kit...
 

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Todd I agree with you in all other situations but have found that there is more in the bike when I drop weight or put my helix on C4 in the dunes to gain more RPM closer to 9200. At 8700 when getting to the top of a dune there is a lot of lugging. I'm sure primarily due to my sandstrippers that are diggers more than floaters. I have always taken your advice and it's been spot on. If there is something I'm missing I'm open to change.
 

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Discussion Starter #6
Todd I agree with you in all other situations but have found that there is more in the bike when I drop weight or put my helix on C4 in the dunes to gain more RPM closer to 9200. At 8700 when getting to the top of a dune there is a lot of lugging. I'm sure primarily due to my sandstrippers that are diggers more than floaters. I have always taken your advice and it's been spot on. If there is something I'm missing I'm open to change.
No you are right on, as Dalton says in the instructions for his kits, "Sand is speculative, some is deep dry sand while others is desert roads and compact beach sand etc"

Point is as mentioned it simply is not black and white, and I can't possibly cover every scenario so I just wanted people to have something to think about and therefore adjust around.

Todd
 

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Thanks Todd. Spoke with you earlier today. Im the guy that rock crawls with larger heavier tires and i also race at 70+ MPH. Im going to set my machine up the best i can so it works decent for both applications. But as you told me earlier. If you want it perfect for fast racing it will be not so good for crawling and visversa. Thanks again.
 

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This is great info. I'm curious about your thoughts on springs.
Maybe it's too much of a can of worms for this thread.

Some kits are just weights. Some kits include springs. Some of the things I've read about springs range from engagement rpm to belt clamping force to backshifting to shifting characteristics. A lot of people say a lot of things and no one really seems to make sense of it all.
 

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Good stuff Todd!
My package is slated to arrive tomorrow with the clutch kit, so we may be talking over the next week!
 

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This is great info. I'm curious about your thoughts on springs.
Maybe it's too much of a can of worms for this thread.

Some kits are just weights. Some kits include springs. Some of the things I've read about springs range from engagement rpm to belt clamping force to backshifting to shifting characteristics. A lot of people say a lot of things and no one really seems to make sense of it all.
Dalton is the whole package including the helix which some say is not needed. I've been fortunate enough to play with most of the kits. Yes just a spring will help but there is more to it than that. When you have the CVT working as it should the benefits of it being tuned are the best mod you can do for the money. I've installed many Daltons for friends and find it the best of the kits.
 

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Discussion Starter #13
This is great info. I'm curious about your thoughts on springs.
Maybe it's too much of a can of worms for this thread.

Some kits are just weights. Some kits include springs. Some of the things I've read about springs range from engagement rpm to belt clamping force to backshifting to shifting characteristics. A lot of people say a lot of things and no one really seems to make sense of it all.
My thoughts on springs only is, Dalton has on one kit that is just springs and that a 2014 ranger 900 kit, they could not make a full kit make it work better.

They have a couple models they say don't do anything to as the stock set up works good for stock vehicles

So whatever they have in a kit, it just needs whatever the parts are

Dalton does not cookie cutter their kits and all models get the same parts.

So to answer your question, unless you have a Ranger 2014 900 and the kit for your model has more than it than spring then it needs it.

Of course there are people who like to play with their own clutching and that is cool, we just have kits that have proven to work and that is what we do.

What Dalton does should answer the last part of your statement, no one makes sense of it all. They do.

Is that arrogant? Yes but Dalton kits just work

Todd
 

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Todd,

This is an amazing explanation and i have never heard any put it in perspective like you have. I currently have a Dalton clutch kit. I wish i would have bought it from you since you seem to be so knowledgeable on the situation. i have 33" BKT tires ( in typical mud ridding fashion lol). i would like to get your opinions on the Dura clutch system. I have a 2016 xp 4 1000 right now and even with the Dalton clutches i still have some belt slip sometimes when going real slow. Don't get me wrong this was a huge improvement over stock clutching. I guess my question is do you think the Dura clutch is really worth the money or do you think a gear reduction would do just fine with the Dalton clutches?
 

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Discussion Starter #18
Todd,

This is an amazing explanation and i have never heard any put it in perspective like you have. I currently have a Dalton clutch kit. I wish i would have bought it from you since you seem to be so knowledgeable on the situation. i have 33" BKT tires ( in typical mud ridding fashion lol). i would like to get your opinions on the Dura clutch system. I have a 2016 xp 4 1000 right now and even with the Dalton clutches i still have some belt slip sometimes when going real slow. Don't get me wrong this was a huge improvement over stock clutching. i guess my question is is the Dura clutch really worth the money or do you think a gear reduction would do just fine with the Dalton clutches?
Gear reduction would be what I say then if you need more do duraclutch

Todd
 
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