Anyone with automotive CVT transmission experience - Page 2 - PeachParts Mercedes-Benz Forum

Mr.Kenny · #16 10-18-2012, 10:51 AM

The Nissan Cube we rented A summer ago with cvt; it always knew what ratio was needed at any moment. It made a small engined car very peppy when needed, and went into a high ratio the moment you let off the accelerator, thus great fuel mileage for a boxy car..... It did all this without any shifting; it was seamless.
But I wondered how long the transmission would last........

Benz Fan · #17 10-18-2012, 11:08 AM

Last week, I had occasion to ride in a 2011 4-cylinder, CVT-equipped Subaru Outback that is the grad-school wheels for the daughter of a friend of mine. She was home for the weekend, and my friend and I were performing a pre-flight check on the car before she went back to school. We pulled into a gas station, and as my friend left the car to prepay for the gas, I noticed that he pulled in on the wrong side of the pump.

I got behind the wheel, pulled away from the pumps, and was performing a three-point turn in a tight area in order to reposition the car. I shifted from Reverse to Drive, and as the pumps were slightly uphill from my position, I gave it a little gas. This thing jumped forward as if it had a 455 Pontiac under the hood, and I had to mash the brake before I took out a gas pump. I once drove a Nissan with CVT, and noted the same tendency to lurch forward at low speeds without forewarning. I wonder if such behavior is endemic to CVT's, or if I'm just a nascent old fart just biding my time until the day that I launch my 10-year-old Grand Marquis through a convenience store window?

BAVBMW · #18 10-18-2012, 11:33 AM

I've been familiar with them, especially in the Mini vehicles for quite some time now. Enough so that when it was time for her to get a new car, we scoured the state to find one of the (only two) manual transmission equipped ones. Really just the one, she didn't want white.

They work well in snowmobiles, and some light utility cart type vehicles. They should stay there.

MV

Palangi · #19 10-18-2012, 11:48 AM

Prius has a CVT. As far as I know, there has not been a history of failures. IIRC, there is no specified change interval (lifetime fill?). People on the Prius forums who have had the fluid analyzed say that by about 80k, the fluid gets to the point where, if it were a conventional transmission, the fluid should be changed. Generally speaking, the Prius forum scuttlebut is that the fluid should be changed at 80 to 100k.

MBeige · #20 10-18-2012, 12:33 PM

We have a 2004 Honda Fit/Jazz overseas. It has the 7-speed CVT. The lurching forward, belt-driven observation, slippage with worn fluid, and requirement to use only CVT fluid, is the same I have observed.

Kickdown is quick, sometimes I can do 3 kickdowns if I wanted to go faster. The Honda Fit/Jazz we have is a 1.3L i-DSi engine (economy model) with dual spark plugs per cylinder and lightweight chassis. The CVT is okay with this chassis where heavy loads are not required.

One or two times I had to drive out of a steep parking ramp, and the car was loaded with 4 people only. I mashed the pedal to go up but it couldn't pull us through. I had to manually downshift to 1st in order to get out.

On certain occasions I am on a hill, and test whether the car will hold the hill like our MB's do. I was surprised to see it was slipping slightly.

From what I've seen the CVT is good for light load applications only. Any heavy towing, etc or large cargo capacity vehicles should have a standard automatic or manual transmission instead. The CVT, from what I've heard, is good for fuel economy partly due to its light load applications (weight will ruin MPG).

Sometimes if the fluid is in need of changing, I would go up a steep ramp and it would lurch forward as if it just grabbed a gear and transmitted the power to the wheels suddenly.

When I was overseas driving the Honda Fit/Jazz, I felt the CVT belt was squealing. I told my dad to get the transmission serviced after the trip. He had it done and no more belt squeal. It required specialized fluid for CVT transmissions only, and being a Honda they wanted to use their own fluid.

With the CVT, the manual 7-speed sport mode did not feel good. Too much gear changes to make plus the sound feedback from the engine was not inspiring. I switch it back to D whenever I can.

retmil46 · #21 10-18-2012, 01:16 PM

Quote:

Originally Posted by Zulfiqar

CVTs are the money making golden egg machine as if there is anything not working right, only a handful repairs are possible - out of that spectrum - Its a $5K plus slap on you.

Fluid change - even at DIY level is expensive, $20/qt and about 7 to 9 qt capacity in a small/medium unit.

The torque convertor type CVTs do make sense but the solid wheel Honda unit did not - why use a motorcycle type system for standstill when the TC has been doing that very nicely for decades.

These days, they're trying to set up ALL types of auto trannys to be dealer service only and money-making machines.

Back in 08, I had the misfortune of getting a Chevy SSR as a rental on a trip to San Antonio. It was a brand new rental, little over 1K miles on it, still had the owners manual and all the other paperwork in the car. I sat down the first day and went thru the manual to figure out how to operate and best drive the POS.

No tranny fill tube or dipstick, "lifetime" tranny fluid. Manual said if you got a leak and needed to add fluid, or had problems, guess what - take it to the dealer.

Even back in 05, when I bought the Jeep Liberty diesel, with a 545RFE auto tranny, DC still hadn't licensed any third-party production of their ATF+4 fluid that it required - only place you could readily obtain it was at the dealer.

In late 06, I checked out one of the CRD versions of the Grand Cherokee with an MB V6 diesel and auto tranny they tried to sell - sealed dipstick tube to where you were supposed to take it to the dealer to unlock so they could add or check fluid level, and voided the warranty if they thought you had tampered with it.

Yeras past, the reason given why over 90% of the cars sold in this country were equipped with auto trannys was that people preferred them so they could use their cell phones while driving. While this may very well be true, I'm now thinking the OEM's and dealers used this as an excuse to do away with any manual tranny option on the majority of vehicles they sold - which require virtually no maintenance - and push auto trannys with their maintenance requirements, and often exorbitant repair and replacement costs.

Zulfiqar · #22 10-18-2012, 01:53 PM

Quote:

Originally Posted by Palangi

Prius has a CVT. As far as I know, there has not been a history of failures. IIRC, there is no specified change interval (lifetime fill?). People on the Prius forums who have had the fluid analyzed say that by about 80k, the fluid gets to the point where, if it were a conventional transmission, the fluid should be changed. Generally speaking, the Prius forum scuttlebut is that the fluid should be changed at 80 to 100k.

I have also seen a Prius CVT opened up, firstly it weighs about as much as the engine, and for drive it uses 2 massively big motors - its fluid is basically used to cool it down and lube for the gear mesh. no hydraulic purpose. It is a good design but extremely expensive to repair.

SwampYankee · #23 10-18-2012, 02:12 PM

No, but I'd imagine somewhere on the web there's someone who's figured out a DIY fluid change on those specific vehicles. Why not change it every 50-80K?

From a cursory search, it would appear the trans. fluid change process on the Honda CVT's is not unlike that on my conventionally transmissioned (?) '03 Honda Odyssey. There is no fill tube and the drain only removes about 1/3 of the fluid, but after seeing the trans. issues this generation Odyssey was having it became part of my scheduled DIY maintenance. For less than $110 (with 10 qts. Honda fluid, would have been less if I went with Castol Import-might do that after the next 50K) including funnel, tubing and clamp it seems like good insurance compared to the cost of a new transmission!

Drain fluid-->refill with new fluid (again, only adding about 1/3 of the total capacity since the drain placement leaves 2/3 of the oil)-->drive 10 miles (or leave on jack stands in drive-I was not comfortable with that!)-->drain fluid-->refill with new fluid-->drive 10 miles-->drain-->refill with new fluid.

The only way to fill it is through the dipstick tube. I used a funnel attached to a 3' length of clear tubing just big enough to fit over the tube and used a hose clamp to keep it tight and hung the funnel from the hood catch with a piece of coathanger so I didn't have to hold it during the nearly painfully slow filling process. From first drain to final fill was about 2 hours and 45 minutes. Now that I know how to do it, I bet I wouldn't even need ramps.

Here's a pic from a guy that did a Civic CVT change:

Palangi · #24 10-18-2012, 03:28 PM

Quote:

Originally Posted by Zulfiqar

I have also seen a Prius CVT opened up, firstly it weighs about as much as the engine, and for drive it uses 2 massively big motors - its fluid is basically used to cool it down and lube for the gear mesh. no hydraulic purpose. It is a good design but extremely expensive to repair.

Good to know that, and thanks for the info.

What would be your recommendation for fluid change interval on Prius?