Parasitic Drivetrain Loss and the Ultramatic CVT

Our Gift to You! 1yr Paid Subscription to Quad Off Road!


	[All Forums] [Most Popular] [HL Related] [OEM] [Swap Shop] [Scott's Pics]	Chat Inbox

Logged in as: Guest

Parasitic Drivetrain Loss and the Ultramatic CVT

Printable Version

View related threads: (in this forum | in all forums)

Users viewing this topic: none

All Forums >> [OEM Discussions] >> Yamaha >> Parasitic Drivetrain Loss and the Ultramatic CVT

Page: [1]

Message

<< Older Topic Newer Topic >>

Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 12:14:15 PM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

Grizzly 660 42HP @ crank.
Grizzly 660 ~30HP @ rear wheels.
Parasitic Drivetrain Loss = ~29%

Only 29% of the available HP at the crank is transferred to the wheels via the internal wet clutch and CVT system!

Most all of the other manufacturers are focusing on building massive powerplants for their new machines instead of trying to develope more efficient ways to transfer this power. Instead of refining the clutching systems, they just throw a bigger, beefier, more powerful motor in so that the rear wheel power is greater, yet the loss between the crank and the wheels is still present.

Now only if there was a way to make the CVT system more efficient.

Automobiles using the CVT systems use stronger belts which incorporate steel belts and "keys" into the belts to allow them to withstand the HP and TQ of a 4-cylinder or V6 engine.

One thing that all CVT systems have in common is the sheave faces being smooth.

So why not knurl one or machine a pattern into the sheave faces to increase belt grip and reduce parasitic drivetrain loss?

The few problems I see with this are as follows:

A) Increased drivetrain wear and tear. Given the fact that wet-clutch systems are most likely the most efficient power distribution system out there, they slip very little once fully engaged. With the smooth sheave faces of the CVT system, they allow belt slippage to occur whether it uses the internal wet-clutch system that Yamaha utilizes, or the Polaris-style CVT system that uses a crankshaft mounted primary. Also, with the belt being mostly rubber, it stretches a certain amount. All of these factors act as a drivetrain "buffer" or "dampener" to decrease stress and wear on drivetrain components. This is much like the rubber dampening bushings (or "cush drive" system) in the sprockets or drive wheels of most motorcycles available these days.

B.) Belt/sheave wear. If you've ever had your belt off, you will see that the sheave faces will, over time, being to groove where the belt rides. They wear like this because they slip. Take away the slip, you take away the grooves. The belts will also wear due to this slippage. However, with the Ultramatic CVT systems, the primary always clamps on the belt. Because of this, I believe one could get away with running a slightly knurled or machined pattern on the sheave face because the majority of the slippage occurs in the wet clutch, and not so much on the belt/sheave faces. This is one of the biggest reasons why the Ultramatic CVT system is, in my opinion, the most reliable belt driven CVT system available. If you tried to knurl the sheave faces on a Polaris or Kawasaki system, the belt would be toast very quickly as the "teeth" would chew the belt very quickly.

Regardless, the knurles or machined patterns would increase belt wear. Without testing though, there's no telling how much wear would increase or how much more efficient the CVT system would be.

BUT, the way I see it, is that even if the parasitic loss is 10% less, that's only a 19% parasitic loss overall, which would come out to 8 more HP than the current setup.

8hp AT THE WHEELS is a HUGE increase in power especially since it's all felt at the wheels and not just "crank hp". Plus, the power is already there. It's practically "free" power.

Now, all of this is assuming that Yamaha or other manufacturers have experimented with this, and found it to be a lesser design compared to the smooth-faced sheave design. BUT, considering the fact that Ultramatic belts hardly ever need changing, I would be able to live with replacing the belt every 1500 miles or so, given the conditions were strictly mud riding.

Any thoughts?

< Message edited by mud_dog450 -- 9/4/2008 12:15:54 PM >

_____________________________

Check out our UPDATED Acceptable Use Policy, here!

The Mud Brothers
Goin' Deep Since 2004!
02 Grizz
Everything Snorkeled
Clutch Work
29.5 Laws on Vision Buckshots

Wet Nitrous and custom EFI conversion in the works...

Muddin Videos

Post #: 1

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 1:18:46 PM

Dezz

Posts: 481
Joined: 1/11/2008
Status: offline

I totally agree with what you are saying. Almost all manufacturers of everything motorized have been just putting bigger and bigger engines in order to make power.
Thing is, we as comsumers feed off this. When the average comsumer (who probably knows nothing about the machines they are buying) and decides he/she wants the biggest/most powerful atv on the market, then they are not going to buy a machine with a smaller engine. EVEN if the smaller engine atv has more power and has better performance all over the board.
This means more money and profit for the manufacturers.
Always remember, the products we get are based on buying habits of comsumers. Manufacturers spend lots of R&D money to find out this information.

Sometimes, our own buying habits prevents us from getting better performing products. Maybe in time things will change.....We are now seeing the change in the automobiles. The next while you are going to see Turbocharging being used alot more in new cars. Using smaller engines to make power of bigger ones. You will also see auto manufacturers make even better performing drivetrains with less parasitic drivetrain loss. They are spending millions of dollars on R&D for the next big things. I can't wait to see what the future holds.

Dezz

_____________________________

1998 Grizzly 600
27 x 12 - 12 ITP Blackwater XT tires - Back Tires
27 x 10 - 12 Inch ITP Mudlite XL - Front Tires
ITP Delta Black Chrome Rims
Uni Air Filter
Warn A2000 Winch
Detroit Gearless Locker
Oxlite CV joint protectors

(in reply to mud_dog450)

Post #: 2

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 1:20:43 PM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

I can't wait either, so Im' trying to figure something out now to hold me over awhile.

_____________________________

(in reply to Dezz)

Post #: 3

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 3:22:03 PM

Dezz

Posts: 481
Joined: 1/11/2008
Status: offline

quote:

ORIGINAL: mud_dog450

I can't wait either, so Im' trying to figure something out now to hold me over awhile.

LMAO......thats funny.
Well, I'd grab the misses and get busy, to pass along the time....seems to work for me....and she don't seem to mind either.....atleast thats what she tells me.....lol......

Take care,

Dezz

_____________________________

1998 Grizzly 600
27 x 12 - 12 ITP Blackwater XT tires - Back Tires
27 x 10 - 12 Inch ITP Mudlite XL - Front Tires
ITP Delta Black Chrome Rims
Uni Air Filter
Warn A2000 Winch
Detroit Gearless Locker
Oxlite CV joint protectors

(in reply to mud_dog450)

Post #: 4

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 3:37:08 PM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

My girlfriend asked me how a motor worked and if she could help me when I work on my Grizzly. I was speechless!

I plan to do some testing on some "ideas" of mine, and hopefully not screw too much stuff up in the process. Atleast now, I have someone to blame it on.

Back on topic.

Anyone have any other ideas on how to improve on the CVT design?

_____________________________

(in reply to Dezz)

Post #: 5

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 8:50:27 PM

YAMAFORD

Posts: 1777
Joined: 9/23/2006
From: Oakfield Ga.
Status: online

I dont have any input on making stock better but I do see alot of 660's running 1.5 inch belt snorkles then big tires and alot of mud. Yamaha must have thoght it need a large snorkle to begin with. I try to keep mine at 2 inchs and have not had a problem with wear unless it was a result of dirt ingested and destroyed my sheaves becouse i didn't get it cleaned out. Sorry to get off topic.

Now for the on topic. Rhino guys in other parts of the country that dont see water are switching over to a wet clutchless design and swear by it. the only problem is the cover wont fit. I cant remember the name but I'll post it if I remember.

_____________________________

Kelvin http://photobucket.com/yamaford

funny vid

http://www.myspace.com/yamaford

MINE

04 660 black
27" SB's CATVO's 10" lift
WIFES
660 RHINO CAMO 28" mudzilla's ss212 black wheels Pioneer CD and 4 Alpine 6x9's.

(in reply to mud_dog450)

Post #: 6

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 8:54:37 PM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

I'd love to see more information on what you are describing YAMAFORD.

_____________________________

(in reply to YAMAFORD)

Post #: 7

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 9:12:04 PM

Mudder_N_Hell

Posts: 1714
Joined: 3/26/2004
From: Lufkin, TX
Status: offline

I agree that a lot of power is lost with the wet clutch design. But as I am sure you know, everytime you change the direction of your drive train, you loose power as well. That is one reason Honda put their engine in longitudinally (and now Polaris) because that reduces the power lost going from the crankshaft/transmission to the internal drive shaft. IRS bikes also loose power in the CVs as well. So keep in mind that you could make some modest gains just with clutch work, but there are parts of the drive train that will continue to rob you of power.

_____________________________

04 Real Tree Hardwoods Grizz Headhunter Edition; Mods: All of them
08 SE Midnight Armor Grizz (New)
99 Wolverine 350
05 Raptor 80
"Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves.
" Ronald Reagan http://community.webshots.com/user/toddlaird

(in reply to mud_dog450)

Post #: 8

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/4/2008 9:18:26 PM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

The point I was trying to make in the original post was that I don't believe the wet clutch is near as bad as the actual CVT belt drive when it comes to loss. Once the wet clutch locks up, it's all good to go.

I think the biggest thing to help reduce power loss would be to roughen up the sheave faces so they don't let the belt slip near as much, if at all. Let the wet clutch take the hit, it will last much longer than the belt IMO.

_____________________________

(in reply to Mudder_N_Hell)

Post #: 9

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 7:03:54 AM

XLCat

Posts: 2181
Joined: 12/29/2005
From: AL
Status: offline

You're loosing 29% but you're still transferring 71%. That's pretty fair. Most don't realize how inefficient the whole process is in any vehicle. You're lucky if you get a piston engine over 35% efficient at the combustion process to begin with. Honda and Polaris both have taken the first obvious step in cutting down drivetrain loss: take away 1 bevel gear set. I don't know why the other manufacturers haven't gone this route yet.

As for knurling the sheaves. I think you'll shred the belt in a matter of minutes. There has to be slippage. The belt curls around the contact patch on the sheave. The face of the belt can't stay static in relation to the sheave face. Even if you remove all load, the belt still has to 'slip'. If it was an infinitesimally thin belt, it could wrap tangentially around the sheave w/o slippage, but that's far from the case.

_____________________________

2007 700 GRIZZLY---Outlaw MSTs: 26x9.5, 26x12; Warn 3000 w Amsteel, (4) CEC 1" spacers, UNI air filter, 1.25" bar relocation, removed shifter lockout, exhaust tip, 9003 SilverStars, (8) 660 weights

1986 TRX200SX parts donor
1985 ATC70---detailed, open air filter, gutted exhaust, jetted, 200sx throttle housing & cable, stripped everything that doesn't make it go!

(in reply to mud_dog450)

Post #: 10

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 8:33:39 AM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

Do you believe anything could be done to the sheave faces, aside from knurling, without complete belt destruction? Rough cross-hatching, coating, etc...?

_____________________________

(in reply to XLCat)

Post #: 11

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 10:43:35 AM

XLCat

Posts: 2181
Joined: 12/29/2005
From: AL
Status: offline

The cross hatching would serve to deglaze the surface for sure. It would eventually wear away as would any type of coating. If I were going to do something, light crosshatching would be an option. If you're not stalling out due to belt slippage it's all a moot point though.

_____________________________

2007 700 GRIZZLY---Outlaw MSTs: 26x9.5, 26x12; Warn 3000 w Amsteel, (4) CEC 1" spacers, UNI air filter, 1.25" bar relocation, removed shifter lockout, exhaust tip, 9003 SilverStars, (8) 660 weights

1986 TRX200SX parts donor
1985 ATC70---detailed, open air filter, gutted exhaust, jetted, 200sx throttle housing & cable, stripped everything that doesn't make it go!

(in reply to mud_dog450)

Post #: 12

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 11:24:15 AM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

Thanks for the input, but I don't see it as a worthless idea. I believe something of this sort would help to put more power to the ground. You have some great points though.

_____________________________

(in reply to XLCat)

Post #: 13

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 12:10:05 PM

loudelectronics

Posts: 2747
Joined: 1/17/2005
From: manitoba
Status: offline

I think you are putting alot on belt slippage. The belt slip is minimal and I am sure results in a very minute loss of power when compared to everything else that can use power. The grooves that you speak in the primary are not from slipping. It is just wear from ingesting dust with a moving belt that is often kept at one throttle position. Two moving forces will eventually wear especially with all the dust that they ingest. To increase power to the ground you would need to create lighter materials in the secondary and primary so less HP is used to spin them. The belt is under tension, tension uses HP to get it to move not to mention the belt is very stiff. Also think of how many times the power changes direction. Everytime the power is moved it is going to be lossed. Think of a PWC. They are direct drive. The power that the pistons make moves a crank that spins a shaft with a prop on it. Still about 8% loss with this method but much more efficient. With a quad with 4wd you have a shaft that runs to the front that spins the gears even when not used (more loss), the rear shaft moves gears and changes direction twice resulting in more losses. Although belts do slip, it is no much especially on an Ultramatic. The ultramatic is also the most efficient belt drive out there.

_____________________________

Grizzly 750fi HMF, K&N XTR's Protaper bars, Rox risers
My Site

(in reply to mud_dog450)

Post #: 14

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 12:48:32 PM

engie

Posts: 5214
Joined: 7/9/2006
From: Jackson/Starkville, MS
Status: online

What XLcat is saying is that the belt has to "slip" into and out of the primary clutch on it's way to the secondary. Think about it...If it didn't "slip" then it could never travel to the secondary. The slip is nonrelational to the actual moving of the quad, but is a "slip" nontheless.

The biggest thing you want to defeat here is heat(friction). (Energy) in = (heat - work) out. Thus you immediately see that every location that creates "heat" will have a parasitic drivetrain loss. This is true for the "wet" clutch, primary clutch, secondary clutch, every gearset out, u joints, cv joints, etc. 29% isn't bad. What I'm saying here is that your not going to gain much in dynamic efficiency by modding the clutches. Alot of the clutch mods that we do actually make the quad more "inefficient" albeit better at a given task. A stiffer secondary spring, for example, will create more friction and heat in the secondary clutches. This hurts efficiency and in the end, the peak horsepower number. Will it be enough to be seen on a dyno? Well, I guess it depends how stiff the spring is. Basically, in a nutshell, your not going to make the design more "efficient" by doing any of the mods your discussing. There are alot of automotive/mechanical engineers out there making a whole lot of $$$ with millions of $$ worth of CAD type computer programs that calculate efficiency before they ever produce it. If there was a greatly more efficient design in the belt system, they would have done it already.

OK...Now, there IS alot of potential gain to be had by "cutting into" the manufacturer's designed "safety factor" in the clutches. While this isn't exactly "efficiency" by definition, it is possible to increase the lowend power and topend power/speed at the same time by modifying different things. Anotherwords, the first thing you should do is be sure that the belt travels COMPLETELY up and down the primary clutch. Any spot on that clutch that the belt doesn't reach is a gain waiting to happen...

Check the last post I made on this. CLUTCHING That's how we are modding the Suzuki(yami with "dry" rollers) setup for about a ~10% lower first gear and ~20% higher top gear...

_____________________________

Team Throwed Offroad crew chief

Building a motor or two with a few other little projects...

quote:

Victory is not achieved on raceday. It is achieved in the preparation leading up to it.

(in reply to loudelectronics)

Post #: 15

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 1:13:41 PM

mud_dog450

Posts: 5557
Joined: 6/20/2004
From: Northeastern Indiana
Status: offline

So in a nutshell, you're saying to lose the entire idea of modifying the sheave faces.

Anywho, thanks for the link engie. I've read it over a few times a few months ago. Mods are utilized to increase belt grip, among other things. Essentially, I was trying to get the same outcome (better efficiency), but using a different method that, in the end, wouldn't be near as effective as I'd imagined.

That's the difference between a mechanic (myself) and an engineer (engie). It's always better to have as many perspectives on things as possible.

_____________________________

(in reply to engie)

Post #: 16

RE: Parasitic Drivetrain Loss and the Ultramatic CVT - 9/5/2008 5:43:12 PM

engie

Posts: 5214
Joined: 7/9/2006
From: Jackson/Starkville, MS
Status: online

It is a good thought...I like the thinking "outside the box" aspect that your using. That's how true innovation comes to pass!

Practically, what you were saying made sense. The thermodynamics of the whole process is quite a bit different, however!!

Funny thing is that when you put on a 2" lift, you are actually losing peak power output to the tires. The reason? More "work" being lost as heat in the cv joints...

_____________________________

Team Throwed Offroad crew chief

Building a motor or two with a few other little projects...