Techies please explain

matthiesen · **Posted:** Tue Apr 11, 2006 2:51 pm

Jeep's CVT transmission.Can it be compared to a snowmobile belt and clutch system?How will it stand up in slow off road crawling?Is the automatic of the future?

Jeepjeepster · **Posted:** Tue Apr 11, 2006 3:23 pm

matthiesen wrote:

Jeep's CVT transmission.Can it be compared to a snowmobile belt and clutch system?How will it stand up in slow off road crawling?Is the automatic of the future?

Maybe I do not know enough but what do you mean by CVT?

matthiesen · **Posted:** Tue Apr 11, 2006 3:46 pm

Continuously variable trans axle(transmission),that's a mouthful...It's in the new Patriot and can be hooked to a transfer case with a low range.

ShoreRenegade · **Posted:** Tue Apr 11, 2006 3:46 pm

I assume you are talking about continuously variable transmission. I don't fully understand it buy I believe it works with a cone/belt system where the belt slides up and down the coned to gradually move to a higher gear ratio based on speed, acceleration, etc. I think it is sort of a sophisticated version of a lawn mower transmission.

I would assume it would not be ideal for off roading. I think offroad situations would "confuse" this type of system significantly. I'll do some research and see what I can dig up.

By the way, I wasn't aware of any jeeps with this sytem. Which one(s) have it???

Jeepjeepster · **Posted:** Tue Apr 11, 2006 3:55 pm

Ahh, yea Ive heard of that. Havent really looked into how it works, yet.

jeepkj02 · **Posted:** Tue Apr 11, 2006 4:17 pm

I dont think any Jeeps came with a CVT tranny. Correct me if im wrong but the Liberty's have the 45rfe (02) and 42rle automatic tranny (03+). CVT trannies usually are in Honda's and other compact import vehicles.

EDIT: found this link about CVT Tranny's. Might answer some questions.

http://auto.howstuffworks.com/cvt.htm

sqliberty · **Joined:** Sun Mar 19, 2006 3:08 pm **Posts:** 207

The Nissan Murano uses this now, it's strange to not feel any shift points. I saw that this will be the Jeep Patriot transmission.

jason thompson · **Posted:** Tue Apr 11, 2006 7:44 pm

the cone belt theory is right
i can tell you this Polaris (snowmobiles & 4wheelers) have them and i have pulled out more polaris 4wheelers that got that belt wet and tried to go only to burn it up in less than a second it is ureal i think that for offroad you need gears be they auto or manuel you still need to tell it to go to its lowest point and stay there
just my .02

valvestem · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 222

matthiesen wrote:

Jeep's CVT transmission.Can it be compared to a snowmobile belt and clutch system?How will it stand up in slow off road crawling?Is the automatic of the future?

Here you go, basically the same as a snow machine. There are 5 types of CVT's, this being one of them. Another type is used in the drive mechanism of snowthrowers.

nickmv · **Posted:** Tue Apr 11, 2006 8:32 pm

i think when you were thinking about hondas you were referring to Continous Valve Timing....an engine efficiency thing

cowpie · **Joined:** Mon Jul 25, 2005 9:00 am **Posts:** 26

jeepkj02 wrote:

I dont think any Jeeps came with a CVT tranny.

Both the '07 Jeep Compass and Jeep Patriot with the 2.4l 4cyl have the CVT transmisson. And if the IFS wasn't bad enough on the liberty, these new "jeeps" have 4 wheel independent suspension. The 2wd versions are FRONT wheel drive. :roll:

ShoreRenegade · **Posted:** Wed Apr 12, 2006 7:47 am

Sounds like the main disadvantage of CVT is they are limited in the amount of torque they can handle. So from that perspective, it would not make a very good offroad vehicle. Further evidence that Chrysler has set out to destroy the Jeep brand image, tradition, and legacy.

Taken rom HowStuffWorks.com

Variable-diameter pulleys must always come in pairs. One of the pulleys, known as the drive pulley (or driving pulley), is connected to the crankshaft of the engine. The driving pulley is also called the input pulley because it's where the energy from the engine enters the transmission. The second pulley is called the driven pulley because the first pulley is turning it. As an output pulley, the driven pulley transfers energy to the driveshaft.

When one pulley increases its radius, the other decreases its radius to keep the belt tight. As the two pulleys change their radii relative to one another, they create an infinite number of gear ratios -- from low to high and everything in between. For example, when the pitch radius is small on the driving pulley and large on the driven pulley, then the rotational speed of the driven pulley decreases, resulting in a lower “gear.” When the pitch radius is large on the driving pulley and small on the driven pulley, then the rotational speed of the driven pulley increases, resulting in a higher “gear.” Thus, in theory, a CVT has an infinite number of "gears" that it can run through at any time, at any engine or vehicle speed.

CVT Benefits:
Eliminates "shift shock" -- makes for a smoother ride
Improved fuel efficiency
Eliminates gear hunting as a car decelerates, especially going up a hill
Better acceleration
Better control over emissions
Replace inefficient fluid torque converters

With all of their advantages, CVTs do have some shortcomings. In the United States, they are still trying to overcome an image problem. The Subaru Justy, for example, was known as a gutless micro-car. Traditionally, belt-drive CVTs were limited in the amount of torque they could handle and were larger and heavier than their automatic and manual counterparts. Technological advances have put CVTs in the realm of their competition -- the Nissan Murano's CVT can handle its 3.5-liter, 245-horsepower V6 engine -- but first impressions are hard to overcome.

matthiesen · **Posted:** Wed Apr 12, 2006 9:21 am

The Rokon motorcycle,produced in the 70's, had a belt drive system and the belt would slip when wet.The Patriot that has the low range transfer case is"trail rated." It will be interesting to see if the media testers can make this transmission fail.By the way,I like the looks and the projected mileage figures of the Patriot.

Jeepjeepster · **Posted:** Wed Apr 12, 2006 9:42 am

I guess the libby is the last real jeep besides the wrangler. The Wk sure is not a jeep and the XK isnt either. Who puts the gas tank in the middle of the car anyway? Our corolla has it in the back!

Mango~Ridge · **Posted:** Wed Apr 12, 2006 8:46 pm

We recently bought a 2004 E-Z-Go 4x4 utility cart, powered by an 18 horse honda with a CVT tranny, electric front & rear lockers. I crawl over 6-8" logs just fine. When crawling over a log stopping on it (take pic) the CVT tranny does real good

I'm still gettin used to the belt drive system, pretty happy with it so far. It came with front and rear class III receivers with a front winch option & rated to pull a 1500 lb trailer around, Pretty handy tool around the lake property. Just another toy, and we love toys

Albert · **Posted:** Thu Apr 13, 2006 9:51 am

I wonder how often that cvt-drive belt has to be changed.............You'd have to drop the tranny....

Mango~Ridge · **Posted:** Thu Apr 13, 2006 4:15 pm

I'm not sure how long the drive belt will last. I asked the dealer the same ?, he doesn't replace that many, so they might be pretty durable, I'll find out eventually. On this honda engine, there's a pully shield you remove to access the belt. Looks to be an easy replacement.

LibertyCRD · **Posted:** Fri Apr 14, 2006 7:45 am

They've been using these trannys on 4x4 ATVs for years. Don't laugh...these ATVs have towing capacities over 1,000 lbs. Anyway, they are very dependable trannys in those applications. The only problems are that they don't like water at all (which sucks for people who'd venture off-road) and the belt requires regular maintenance intervals to keep it tight and inspect it for wear. I guess we'll see how well they do in automobiles over the next few years...

matthiesen · **Posted:** Fri Apr 14, 2006 9:51 am

There is a picture of the inside of the Trans. on allpar.com.Looks as if the belt is sealed inside the case.Jeep is claiming the Patriot is Trail Rated and that includes ,I think,an18 in. water crossing ability.We shall see in time how well this new technology works.

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