CVT belt life

[canamryder]

Thanks

Just to be clear, the CVT fan has nothing to do with the coolant fan. While you are able to hear the coolant fan cycle on and off. The CVT fan is always spinning whenever the engine is running. Since the CVT fan is located on the drive side of the CVT system, it will turn at engine RPM speed regardless of belt or outside air temps.

Part #16 in this diagram is surely the fan, though BRP designates it as an 'Inner Half Assembly'. But you can see the classic centrifugal impeller design on this part.

View attachment 181494

What is not clear to me (Opening up my CVT drive system may clear this up) is whether this fan merely circulates air within the assembly (not likely. You wouldn't need a scoop or air filter for this, I don't think) or sucks in air through the intake and blows it out through an exhaust port (which is much more likely the case).

I feel that the large increase in air volume that the K&N can flow to this cooling system will definitely be a big advantage. Not to mention the savings over the OEM paper, throw away filter and, hopefully, extended belt life.

Thanks for the(more)info. I also upgraded the plugs to NGK CR8EIX 4218. I will go out soon for a couple smiles. :yes: BTW I had to raise the Clam Shell to get the front plug out.

 

[SportsterDoc]

..What is not clear to me (Opening up my CVT drive system may clear this up) is whether this fan merely circulates air within the assembly (not likely. You wouldn't need a scoop or air filter for this, I don't think) or sucks in air through the intake and blows it out through an exhaust port (which is much more likely the case)...

The parts diagram seems to indicate an exhaust port in the variator housing. The diagram is to the left on the page of the one that you posted.

https://www.canampartshouse.com/oem...a8661634626b82/transmission-cvt-cover-900-ace

 

[SportsterDoc]

BTW I had to raise the Clam Shell to get the front plug out.

Was that due to the length of the spark plug socket extension?
For example, if a 3" extension was too long, would a 1" work?

 

[Rob Rodriguez]

Part #16 is the other half of the driven clutch.. It has "blades cast in it and I'm sure it serves a somewhat dual purpose to pull air through the plastic housing but I'd more say those "blades" are used for heat dissipation and added strength. The face with the "blades" is right up against the engine so its a warm area with engine and belt heat. The cooler you can keep the clutch faces the cooler the belt runs. This means better performance and longer life.

 

[canamryder]

Was that due to the length of the spark plug socket extension?
For example, if a 3" extension was too long, would a 1" work?

This reply was moved to "Ryker Spark Plug Upgrades"

 

[BajaRon]

Part #16 is the other half of the driven clutch.. It has "blades cast in it and I'm sure it serves a somewhat dual purpose to pull air through the plastic housing but I'd more say those "blades" are used for heat dissipation and added strength. The face with the "blades" is right up against the engine so its a warm area with engine and belt heat. The cooler you can keep the clutch faces the cooler the belt runs. This means better performance and longer life.

I don't mean to be nit-picky (as I go about being nit-picky). So, I apologize right at the beginning. But Part #16 is the drive pulley. Part #22 is the driven pulley. Not necessarily important here except that being the drive pulley connected directly to the engine crank shaft, it is always turning at the same RPM as the engine. The very nature of a CVT tends to keep the engine RPM at optimum. Which means that it typically stays within a narrow RPM range (unlike the typical engine which starts at a low RPM, increases RPM until a shift point is reached, and repeats the cycle). This narrow RPM range allows engineers to tailor fan impellers to be most efficient and move the maximum amount of air within this RPM range. The driven pulley (#22) would be a bad choice for a fan because its RPM varies greatly. It probably turns more slowly than the drive pulley under normal conditions. Plus, its location may not be as advantageous to air movement over the entire system.

It is clear that BRP has gone to great lengths to keep this drive belt cool because this system is moving a surprising volume of air. That is why I believe the primary purpose of pulley #16 is to move air. Strength and conductive heat dissipation from the impellers could well be secondary benefits. I would say that the drive pulley endures more stress than the driven pulley.

The driven pulley (#22) above pulley #16 also has fins. Quite likely for added strength as you mention. But they are not configured as impellers as is the lower pulley.

 

[old Timer]

I don't mean to be nit-picky (as I go about being nit-picky). So, I apologize right at the beginning. But Part #16 is the drive pulley. Part #22 is the driven pulley. Not necessarily important here except that being the drive pulley connected directly to the engine crank shaft, it is always turning at the same RPM as the engine. The very nature of a CVT tends to keep the engine RPM at optimum. Which means that it typically stays within a narrow RPM range (unlike the typical engine which starts at a low RPM, increases RPM until a shift point is reached, and repeats the cycle). This narrow RPM range allows engineers to tailor fan impellers to be most efficient and move the maximum amount of air within this RPM range. The driven pulley (#22) would be a bad choice for a fan because its RPM varies greatly. It probably turns more slowly than the drive pulley under normal conditions. Plus, its location may not be as advantageous to air movement over the entire system.

It is clear that BRP has gone to great lengths to keep this drive belt cool because this system is moving a surprising volume of air. That is why I believe the primary purpose of pulley #16 is to move air. Strength and conductive heat dissipation from the impellers could well be secondary benefits. I would say that the drive pulley endures more stress than the driven pulley.

The driven pulley (#22) above pulley #16 also has fins. Quite likely for added strength as you mention. But they are not configured as impellers as is the lower pulley.

Ron, one of the best descriptions of what a CVT transmission really does. CVT trannys are tuned to keep the engine operating in its maximum torque range as its the torque (twisting force of the output shaft of the engine) that powers the vehicle. Horse Power is a calculated number, a combination of that twisting force and the RPM of the output shaft.

 

[Rob Rodriguez]

"That is why I believe the primary purpose of pulley #16 is to move air."

Not to disagree with you but.....The primary purpose of part #16 is being 1/2 of the driven (primary) clutch. It creates the inner sheave face (the belt rides on these faces) of the primary clutch. Without part #16 there is no driven clutch. The ribs cast into the back side of the sheave face are there normally. Just as they are on secondary (driven) clutch halves. The purpose of those ribs is for strength and heat dissipation. This is how primary clutches have been designed for a long time. BRP did do a rather clever thing and shape the "ribs" on part #16 to be more like fan blades and yes I agree they did this so they would help move air through the system (housing). This however is not the primary purpose of part #16. The clever idea is just a a way to make part#16 serve multiple purposes.

Here is a picture of the the backside of a normal driven clutch. The ribs are there (strength and heat dissipation).

 

[chris56]

Hi Ron, is there built in a second temperature-sensor for the gearbox. ??
if I stress my Ryker ... uphill a very steep gravel road 2up, the fan started really loud, but the engine showed no higher temperature !?!
also when I got stuck in the sand on the coast and tried to come out, (could not - without help) the noisy fan started, the engine was not too hot ..
my belt is still OK (11.000 miles)

 

[old Timer]

Chris, are you hearing the thermostatically controlled electric fan behind the engines radiator keeping the engine cool with out airflow created by sufficient forward vehicle motion to to create enough airflow to keep up with demands of higher heat generation as a result of the increased power requirements of your riding conditions.

A mouth full......

 

[BajaRon]

Ron, one of the best descriptions of what a CVT transmission really does. CVT trannys are tuned to keep the engine operating in its maximum torque range as its the torque (twisting force of the output shaft of the engine) that powers the vehicle. Horse Power is a calculated number, a combination of that twisting force and the RPM of the output shaft.

True...

Hi Ron, is there built in a second temperature-sensor for the gearbox. ??
if I stress my Ryker ... uphill a very steep gravel road 2up, the fan started really loud, but the engine showed no higher temperature !?!
also when I got stuck in the sand on the coast and tried to come out, (could not - without help) the noisy fan started, the engine was not too hot ..
my belt is still OK (11.000 miles)

There is no thermal sensor in the gear box. The gear box fan is crankshaft driven off the engine. It turns all the time the engine is running. I highly doubt that it can be heard with all the other goings on in the gear box.

Chris, are you hearing the thermostatically controlled electric fan behind the engines radiator keeping the engine cool...

Exactly. 2 separate cooling systems for 2 different drive systems. Completely unrelated.

 

[BajaRon]

"That is why I believe the primary purpose of pulley #16 is to move air."

Not to disagree with you but.....The primary purpose of part #16 is being 1/2 of the driven (primary) clutch. It creates the inner sheave face (the belt rides on these faces) of the primary clutch. Without part #16 there is no driven clutch. The ribs cast into the back side of the sheave face are there normally. Just as they are on secondary (driven) clutch halves. The purpose of those ribs is for strength and heat dissipation. This is how primary clutches have been designed for a long time. BRP did do a rather clever thing and shape the "ribs" on part #16 to be more like fan blades and yes I agree they did this so they would help move air through the system (housing). This however is not the primary purpose of part #16. The clever idea is just a a way to make part#16 serve multiple purposes.

Here is a picture of the the backside of a normal driven clutch. The ribs are there (strength and heat dissipation).
View attachment 181530

Here are excerpts from a patent application for a bolt on fan assembly for a CVT transmission. Very wordy legal/technical language (below the diagrams), but I did not want to paraphrase.

This patent application, no doubt, comes from either an aftermarket company, or, more likely, the original manufacturer wanting to upgrade their product. All of these fan assemblies that I have found, whether incorporated into the clutch itself, as is the case with the Ryker CVT, or added to the original assembly (as is the case with this patent), are always located on the DRIVE pulley. Never on the DRIVEN pulley. The primary pulley or clutch being the drive. The secondary pulley or clutch being the driven.

This application is for a snowmobile. But the system components function the same. You can click on, or hover your mouse pointer over the pictures to enlarge them.



Here is part of the patent application description. 1. A fan disk for cooling a drive clutch, sheaves, and a belt of a continuously variable transmission, wherein the fan disk is oriented with the vanes directing air through the bore and toward the drive clutch; and cooling the drive clutch by rotating the fan disk and directing air toward the drive clutch.

You can find the entire patent here. https://patentswarm.com/patents/US8776930B2

 

[BajaRon]

As temperatures begin to heat up. And the Corona Virus restrictions lifted. It will be interesting to see if the 'Smell of Hot Rubber' increases with Ryker owners. I think this will be inevitable as the clutch and belt probably do get pretty warm. There may be a curing process as well. In which case, the smell may dissipate over time naturally. I'd say snowmobile riders might be our best, initial information source on this subject. Since they have been running this system for a long time. Though they obviously do not have the ambient air temperatures that we will encounter.

It is interesting to me that cooling fans have been added to snowmobile applications. If they need CVT cooling. What does that say for us?

Only time will tell. Suffice to say that anything we can do to increase air flow over the system will probably pay dividends in belt life expectancy.

 

[63amg]

It is interesting to me that cooling fans have been added to snowmobile applications. If they need CVT cooling. What does that say for us?

Only time will tell. Suffice to say that anything we can do to increase air flow over the system will probably pay dividends in belt life expectancy.

Was reading the Ski-doo forum (not sure if I can post the link) but they're getting between 12-15K on the belt depending on how you drive. They are running Gates Carbon belt on the 1200 models and 900 models. Drive belt width new is 34.925 mm (1.375 in), and wear limit is 32.512 mm (1.28 in).

 

[Rob Rodriguez]

As temperatures begin to heat up. And the Corona Virus restrictions lifted. It will be interesting to see if the 'Smell of Hot Rubber' increases with Ryker owners. I think this will be inevitable as the clutch and belt probably do get pretty warm. There may be a curing process as well. In which case, the smell may dissipate over time naturally. I'd say snowmobile riders might be our best, initial information source on this subject. Since they have been running this system for a long time. Though they obviously do not have the ambient air temperatures that we will encounter.

It is interesting to me that cooling fans have been added to snowmobile applications. If they need CVT cooling. What does that say for us?

Only time will tell. Suffice to say that anything we can do to increase air flow over the system will probably pay dividends in belt life expectancy.

The snowmobile CVT systems used to be "open" on the side facing away from the engine with a simple metal plate belt guard on top. Over time some manufacture's (brp being the primary one) started encasing their cvt system in a plastic housing. Similar to the Ryker. At the same time all ATV CVT system are encased in some sort of housing to keep mud, dirt, water, etc out. Encasing the CVT drive causes it to run hotter obviously which is bad for belt life and performance. You also have to remember some of these high performance snowmobile engines found on factory sleds and ATV's are pushing 200hp (stock). Higher horsepower, more torque, more stress on the belt. One of the ways manufacturers deal with the heat build up is to mold the CVT housing in such a way as to capture fresh outside air and push it through the CVT housing. You see a setup like this on the Ryker and its common on sleds and ATV's as well. I hadn't seen these CVT fans shown in the patent but obviously the "bolt on" fan disk the patent shows and the fan blades cast into the clutch casting of the Ryker is an attempt to get more air through the system to keep the belt cooler. The Ryker belts are running at a fairly low horsepower number compared to their sled and ATV applications but certainly higher outside air temps than the sleds but not the ATV's. As a general rule you don't smell belt burn on a sled unless the CVT is improperly adjusted or you have shredded the belt (belt has over heated and failed).

 

[chris56]

I only have the "Smell of Hot Rubber" if I push her really hard .. we use her more for longer tours (11.000 miles now), maybe the Rally-ryders have more problems with this ..
But someone told me its very urgent to "warm up" the belt before I make some burn-outs or high-speed tests ! I use a "stronger" mapping now, so maybe this will reduce the belt-live, so maybe the stronger Maverik-X3 belt works also for the Ryker ???

 

[BajaRon]

Was reading the Ski-doo forum (not sure if I can post the link) but they're getting between 12-15K on the belt depending on how you drive. They are running Gates Carbon belt on the 1200 models and 900 models. Drive belt width new is 34.925 mm (1.375 in), and wear limit is 32.512 mm (1.28 in).

I've read mixed reviews on the aftermarket belts, including Gates. Hard to know for sure which way to go. Some report excellent service. Others say they are junk and only OEM will hold up.

Aftermarket belts are certainly less expensive. I have found that less expensive does not necessarily translate to an inferior product.

For example. EBC rotors have proven to be much superior to OEM. Yet they cost about 1/2 the price. It does go both ways though. So the old adage, 'You buy cheap, you get cheap' has to be considered.

One thing is pretty sure. BRP/Can-Am are not making these belts. A good guess is that one of these aftermarket companies, like Gated, are making this belt and branding it for BRP/Can-Am. While they could spec it out differently. I don't think in likely. Same with oil and a lot of other Off-The-Shelf items that come in a BRP box.

 

[Rob Rodriguez]

Someone here noted they thought Timeken (the bearing company) was making CVT drive belts for all the OEM's and after market people? Maybe?

It's like covers. BRP sells a snowmobile cover for about $300. You can buy the same cover without BRP decals on it from Kimpex for about $125.

 

[RykerUSA]

I have about 15000 miles on my Rally. I ran across a bell issue once when riding at interstate speeds with a dirty CVT air filter. I agree with previous post that the CVT puts through a huge amount of air and the CVT filter gets dirty in 1/3 the time that the normal engine air intake filter gets dirty. Yes, I could smell the burning rubber as well as had belt slippage at higher speeds.

To solve the issue prior to getting home, I remove the CVT filter and put a cloth around the CVT intake vent secured by rubber band. Yes, call me macgyver.

 

[BajaRon]

I have about 15000 miles on my Rally. I ran across a bell issue once when riding at interstate speeds with a dirty CVT air filter. I agree with previous post that the CVT puts through a huge amount of air and the CVT filter gets dirty in 1/3 the time that the normal engine air intake filter gets dirty. Yes, I could smell the burning rubber as well as had belt slippage at higher speeds.

To solve the issue prior to getting home, I remove the CVT filter and put a cloth around the CVT intake vent secured by rubber band. Yes, call me macgyver.

Sounds like a plan to me!