CVT and Off-road

ABFoz said:
I guess Subaru engineers and designers have been doing big strides with their tech to be able to convince a car guy to like it.
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IMHO they're the best at CVT in the world.

ABFoz said:
I am somewhat curious about the stepped shift points. Some people say they are for marketing purposes only. I am thinking it's for a bit more control to the driver.
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It is for marketing purposes. The only reason why they put in stepped shift points is to appease those that like the feel of a gear shift and is actually less efficient than not having them.
 
daklakfoto said:
That's true. I witnessed 19 fozie sport handle rutted much better. It seems the software is updated. However, traction is still weakness as it is not true locker. Torque vectoring is still reactive. It seems on newer cvt SK they have more confident thus keeping power to wheels in deep sand/mud mode rather than cut it too soon.

Older SJ I'll say off with traction control or use locker.
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It would be nice for consumers to be able to adjust torque mapping in the AWD system like what people used to do pre-2012 with the use of Subaru Select Monitor. With it, the system won't limit the torque just to save the CVT chain but I understand that it is properly risky because the materials used in the powertrain of pre-SK Foresters are different. They actually had to do revision on the SGP powertrain for improved power handling.

Lockers are, of course, a game changer in Subaruing. With CVTs, particularly, the system does not have to increase too much fluid pressure to the transmission when the rear diff locks, reducing the overall stress the system makes. Many passengers though can't live with the clicking associated when turning. I am not bothered by those, to be honest, but I can imagine passengers and those not usually associated with off-roading/touring complaining about the increase in NVH.

Ben Up North said:
IMHO they're the best at CVT in the world.

It is for marketing purposes. The only reason why they put in stepped shift points is to appease those that like the feel of a gear shift and is actually less efficient than not having them.
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Transmission and CVT experts here say the same. They put it above Toyota's Aisin CVTs. What they say may be irrelevant because of our 4.5 million population but they have the experience required to claim such due to the fact that we.get.so.much.JDM.imports here giving them the work hours they need to build their opinions and insights.

The experts/technicians also commend the use of Extroid CVTs by Nissan on the Cedric. They have been testing the technology since the late 90s and so far has been worry-free. The Cedric drives like the directness of the delivery of the system is just out of this world. When I was driving RWDs before I considered the Cedric but the parts were hard to find due to the car's limited production.



It may be too late for many manufacturers to adopt the technology, considering that electric cars are just around the corner and that the oil for the Extroid CVTs are still too expensive.
 
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I still don't think these cars are cutting the power to save the CVT. When new CVT Subaru's are sitting there not spinning any wheels with the foot to the floor, it just looks exactly the same as the older auto Subaru's. I've seen auto L series, SG's and H6 5 speed Outbacks all sitting there, foot to the floor, not spinning any wheels. The cars need better gearing, which is why other auto 4wd's have low ranges or crawler gears. And don't think your CVT is being saved when you are sitting there foot to the floor not spinning wheels, a guy in my local Mtnroo who keeps doing this is on his 3rd CVT gearbox in very little time.
 
@Red XS think you have a point here. If toy really look at all gearing ratios for all subies, they are pretty much fixed at about 14.4x. That's why I have been looking for any supporting doc on what xmode added to this weak gear ratio.

I just came back from somewhat a rocky trail play with all 4x4 (mostly jeeps-mengal pass in death valley - u can YouTube to see). I can truly see how 4L and gear ratio help them just get the torque to wheels to climb.

Imagine what if Subaru puts a 18x or 20x gear ratio in their awd system?
 
@ABFoz I wonder why dont they use this Toroido?

As far as hybrid car, cvt is the way to go so it can accept input from either hybrid or gas/diesel engine.

I expect huge changes in design and future car capable for "off-roading". I just hope I got enuf mulla to get them. ;)
 
Red XS said:
I still don't think these cars are cutting the power to save the CVT. When new CVT Subaru's are sitting there not spinning any wheels with the foot to the floor, it just looks exactly the same as the older auto Subaru's. I've seen auto L series, SG's and H6 5 speed Outbacks all sitting there, foot to the floor, not spinning any wheels. The cars need better gearing, which is why other auto 4wd's have low ranges or crawler gears. And don't think your CVT is being saved when you are sitting there foot to the floor not spinning wheels, a guy in my local Mtnroo who keeps doing this is on his 3rd CVT gearbox in very little time.
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Whoa, he's harsh on the transmission.

Anyway, when the pedal, the engine is revving and the wheels are not moving, the CVT fluid will heat up quickly, especially due to the fact that the fluid goes around in a shorter distance around the torque converter, valve bodyand the actuators in the input and output shafts, unlike in auto transmissions where the fluid travels through the torque converter, valve body and all the gears in the whole casing. I haven't owned a CVT yet but if I will, I will definitely invest in transmission cooling upgrades

daklakfoto said:
@ABFoz I wonder why dont they use this Toroido?

As far as hybrid car, cvt is the way to go so it can accept input from either hybrid or gas/diesel engine.

I expect huge changes in design and future car capable for "off-roading". I just hope I got enuf mulla to get them. ;)
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I don't know yet. Probably because of the fact that Nissan's Xtronic CVT has bad reviews in some markets and due to the fact that they are still somewhat experimental, hence their limited production with the Nissan Cedric. Also, the friction-enhanced fluid is still rather expensive.

There were rumours, though, that they would put it in a Patrol, although in a much smaller engine because of the 39.5 kg-m torque limit.

Kevin said:
I wonder if the dual clutch transmissions are better off-road?
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I thought about that too. Dual-clutch transmission with an aggressive low-range may be able to do it but at the moment, the biggest failures in DCT come from the actuators. Second only is overheating, where it is demonstrated by Hyundai and Volkswagen DCTs in regular stop-and-go traffic. In those low-speed situations, DCTs experience clutch driver-like conditions, hence the overheating and premature wear of the compound. Actuator failure is a big issue, though. It has been 20 years already since DCT was included in regular cars and the same still fail like it's a default feature. :(
 
@Red XS @ABFoz @Kevin since we talked about how newer subie CVT is acting similar to older or auto, I like to post this video for us here to see it first on how my car "stall". Some blames for CVT, other blames for engine stall, still other says gear ratio. I love to hear your opinion.

( will be done uploading in 1 min).
 
Yes, as you said, more momentum was all it needed ;)
 
I think you did a good job there, @daklakfoto. That was just good enough momentum for the obstacle.

Regarding your question, hmmm, is TC OFF and X-mode ON?
 
X-mode is ON.

With locker, i found TC on is actually better, but for this scenario, i did not try turning it off.
 
I would put it definitely at torque converter stall speed and that's why @Red XS said that he found the same behaviour in some 4EATs.

Thanks for the clip, mate! I know haven't driven a CVT off-road yet but your video clearly shows that what everyone is claiming about the CVT limiting the performance is invalid. It's just the torque converter stall speed. Now when the pedal is on the floor and the ECU/TCU tries to compensate, when the wheels are not moving, the fluid in the torque converter heats up quickly and the heated fluid will distribute to the casing and other parts of the transmission like the actuators for the input/output shafts, and when they break, fluid pressure is lost causing failure on the other components. By fluid dynamics and since CVTs have fewer components than plantetary-geared autos and fluid travels in shorter distances, overheating is achieved much more quickly.

It happens with autos too but we already have around 70 years of development so we have better metallurgy and cooling methods vs CVTs.

Now, torque converter design in Subarus varies as commonly as the size of their sway bars in different markets. The torque converter in my SG has I also found out that they didn't put the same cooling system that they do with the Foresters/Subarus outside of the US. I don't know why. There should be 2 extra coolers located in different parts of the bay to help with cooling in different situations. In older CVTs in the US, they are absent.

What you did there with the slight momentum is what I would do too in any case that the vehicle stalls. Other people would keep their foot on the pedal until the computer figures out that more fluid pressure is needed but it can be a bit too late when the fluid is already too hot.

Here in NZ, we have a 30,000km fluid change interval with 4EAT, 5EAT and CVTs because of the harsh conditions the vehicles are experiencing. Make sure you have an aggressive fluid change interval as off-roading is definitley harsh on the vehicle. Cheers.
 
The CVT torque converter having less fluid circulating so heats up faster concept answers a bit. Thanks for that @ABFoz!

The extra traction from traction control or a locker will give the torque converters a harder time as it can't just spin wheels on the spot easily, but in these situations the traction control would be doing more good then harm, just need to keep the car moving.
 
Welcome. Credit to the video by @daklakfoto. It showed proper stall speed limit behaviour, which when prolonged will overheat any transmission with a torque converter. Most of the videos are somewhat unconvincing like those by TFL.

Many people just blamed the CVT system immediately but Subarus use chains and they don't exhibit belt slip/failure, except in TR690s but with tuned WRXs. The belts don't fail but they show shavings which point to high friction and tension situations. The torque converter stall speed engineering just makes proper sense in limiting the power to the wheels (Classic Subaru where they go mechanical first than electronic). That may mean that the 2019 has a more aggressive torque converter.

If I am to off-road a CVT, I would probably install another transmission cooler and/or add active cooling while monitoring the temperature through an app.
 
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@ABFoz @Red XS so happy with your detail explaination to put my mind at eased. I was glad it is normal in the engineering of the car.

However, i am hoping that they up the gear ration or the durability of the system to deliver more power to wheel offroad.

I do have tranny cooler and it is a game changer. Now with locker, i am so happy with the traction aid as well as confirmation that it will help the car.

Now I'll see how long this weak CVT can last. :) I have TR690s high-torque CVT in my 18 FXT. :) :) ;)
 
It should be fine. Heat is the enemy. Also once the oil is broken down it looses its thermal capacity, loosing efficiency, and heating up much more quickly. Just like in planetary-geared automatic transmissions that are poorly designed, a cooler and an aggressive ATF replacement plan takes care of the overall health of the transmission.

If you can also monitor your fluid temp, once the fluid is stressed and is at a higher temperature than usual, you can do a quick drain and fill afterwards. There can be quite a price with that but hey, we gotta pay to play.

The TR690 is one of those solid ones that only had minor problems in its first run due to the following:
  1. Bad torque converter - replaced in recalls - 2009 to 2011 in NZ.
  2. Seal leak in the front of the casing, causing the transmission to loose fluid and then with higher temps and pressure than usual, would blow up eventually
  3. A noisy bearing, which is common with most CVTs due to manufacturers skimping on quality.
Since yours is a 2018, you should have the latest revision from Subaru.

By the way, the price of the fluid for the sweet Toroidal CVT from Nissan is NZD 189 per litre. They call it liquid gold. If other manufacturers adopt the design, there is a chance the price goes down but many are already heavily invested on the belt types.
 
I have already up my cvt oil change to 15k miles or 24.1K km. I do plan to change it regularly at around 20k miles or 32k km. The interval of my cvt oil change will be dependent on trail run and weather. when it is more hot aka summer, i'll change at 15k vs 20k miles. That should be good to prolong the cvt.
 
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