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Discussion Starter · #1 ·
Hello All, My 2020 Ascent Limited with 16,500 miles did something new today. First drive of the day, I let the engine warm up to normal idle speed before moving out of my driveway. Drove through my neighborhood to the stop sign before turning onto a major 3 lane artery with a posted 45 mph (which means 50-60 mph for most). So far so good. Typical smallish gap in traffic for a right turn in front of on coming traffic. As I was making my right turn I noticed cars are moving a little faster than normal so I accelerated a little harder than normal to stay ahead of the flow. Nothing crazy. As I was making the turn and accelerating my wife and I both heard a brief groan/growl sound that emitted from under the car. First time I've heard this and I'm concerned that it may have been the CVT belt slipping. I'm not overly concerned yet but I'd appreciate hearing back from others that may have had a similar experience. Thanks.
 

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CVT belt slipping.
There is no belt...it's a chain in the Subaru CVTs.

There have been a few threads that folks experienced noises in a turn like that. I seem to remember them as being more about suspension/linkage, but I could be wrong about that.
 
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Discussion Starter · #3 ·
There is no belt...it's a chain in the Subaru CVTs.

There have been a few threads that folks experienced noises in a turn like that. I seem to remember them as being more about suspension/linkage, but I could be wrong about that.
Thanks Jim. My bad. I know it's a chain but I when I think of CVT I always think of a belt like a snowmobile. I'll get over it. I hope you're right that it's just the suspension. Best
 

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Hm. "Growls" when turning have usually been wheel bearings in my experience...assuming the sound is coming from the general direction of a wheelwell. If it's coming from more of the center region of the car, I'm trying to think of the things turning under there...driveshaft u-joint, the transfer case/clutchy deal/center diff that the Ascent uses...not sure what else.
 

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It could be the AWD transfer clutches. When you're in a relatively tight turn, the speed differences are greater between the front and the rear. And when you're accelerating hard, that's when the AWD system is trying to transfer the most power to the rear. In this case, it may be the "somewhat normal" noise of the AWD clutches engaging and doing what they do.

Our 2020 model will also do this. It's most apparent in a right turn onto another road because those are usually the sharpest.
 

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IMO, it's fine to call it a belt and more appropriate than calling it a chain because it functions as a belt engaging smooth pulleys via friction rather than as a chain engaging cog teeth. I'm sure marketing thinks calling it a chain sounds better than belt.
 

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Upon further reflection, I remembered there are toothed belts that do engage cog teeth, and they're not generally called chains, even though the function as chains would. So, call it whatever you'd like.
 

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This is what the CVT chain looks like in the TR690 that's used in the Ascent.

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Well, in the CVT world, there's also other considerable differences between a belt and a chain. In cars, a CVT belt is a banded pushbelt. The elements on it are pushed forward by the drive pulley to drive the driven pulley. This creates an interesting dilemma of keeping the non-riding parts of the belt rigid to push the driven pulley, while flexing the steel bands around the pulleys, and thus creating gaps between each element while also trying to use the elements to grab the pulleys. It's really a horrible and quite low torque design that doesn't compete with chain driven systems.


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On a "pull" chain driven system, none of that occurs. There's no metal fatigue from flexing a steel band, there's no elements moving in relationship to each other. Once a chain's guide pins contact the pulleys, they simply stay where they are. These chain based systems can handle 2-4 times the torque of a pushbelt system.

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  • One is called a "belt" because it's literally a banded belt.
  • One is called a "chain", because it's literally a chain, with links and pins (things all chains have and things no pushbelts have).

They are not, and have never been the same - except for when Nissan/JATCO started exploding belts and tried usurping the "CVT chain" moniker while not actually changing to a chain.
 

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Discussion Starter · #12 ·
  • One is called a "belt" because it's literally a banded belt.
  • One is called a "chain", because it's literally a chain, with links and pins (things all chains have and things no pushbelts have).

They are not, and have never been the same - except for when Nissan/JATCO started exploding belts and tried usurping the "CVT chain" moniker while not actually changing to a chain.
Thanks to everyone for their comments. I have to admit I didn't expect to start a discussion over belt vs. chain but it is interesting and informative. I do understand that the CVT has a chain and I'm not trying to defend my position but it relates to my background. In my way of initially thinking of the CVT chain design it's still a belt. It may be made of metal with links and pins but it's a belt. It doesn't engage drive or driven gears with teeth like a some motorcycle chain or engine timing gears.

However, having said that and I hope you forgive me for going into this again, henceforth it is now and forever a CVT chain and I promise I will always refer to it as such 😁.

Back to my original issue, I've tried to repeat the conditions and listen for the sound for a better determination of the source. I may have heard a muted groan/growl once but that's it and I suppose it's a good thing that I'm not hearing anything unusual. Should it come back I'll be sure to let you know.

Thanks again and I hope everyone had a great Thanksgiving! Best, John
 

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John, there are some diagnostics that the dealer service can run to see if there's anything actually showing up as faults, etc. I think I'd do that at least if you hear this again. Given it happens in a tight turn, it could be a combination of suspension/drivetrain, too. It's good to keep your eye on it for sure.
 
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Thanks to everyone for their comments. I have to admit I didn't expect to start a discussion over belt vs. chain but it is interesting and informative. I do understand that the CVT has a chain and I'm not trying to defend my position but it relates to my background. In my way of initially thinking of the CVT chain design it's still a belt. It may be made of metal with links and pins but it's a belt. It doesn't engage drive or driven gears with teeth like a some motorcycle chain or engine timing gears.

However, having said that and I hope you forgive me for going into this again, henceforth it is now and forever a CVT chain and I promise I will always refer to it as such 😁.

Back to my original issue, I've tried to repeat the conditions and listen for the sound for a better determination of the source. I may have heard a muted groan/growl once but that's it and I suppose it's a good thing that I'm not hearing anything unusual. Should it come back I'll be sure to let you know.

Thanks again and I hope everyone had a great Thanksgiving! Best, John
Hi John, sorry, the response was to a question somewhere mid-thread - though it is relevant to your issues in what is likely to fail or not to fail at least (eg: a Nissan belt failing was a thing, while a Lineartronic chain failing - especially the beefy TR690 chain - is virtually unheard of).

So, on to your situation... if you can safely recreate and record it, I'd love to hear it. Various parts of the VDC, ABS and/or X-Mode systems can cause a "growl" sound - as can certain tires on certain pavement (when those systems activate). In most cases, it may be normal. In some cases, it may be something like the AWD transfer clutch needing to "relearn". In other cases, it may be an internal issue in the CVT (generally caused by a control issue or hydraulic issue).

BUT... like @Jim_in_PA said, bringing it in for diagnostics is the best thing to do - they can hook up the diagnostics computer to the car, recreate the sound, and see exactly what the CVT is doing in excruciating detail.
 

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We have a 2021 Ascent and the same noise occurs. When I asked the service manager at our local dealer he said it was “normal” and part of the turbo mechanism. Sounds a little like BS but that’s what he said.
 

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We have a 2021 Ascent and the same noise occurs. When I asked the service manager at our local dealer he said it was “normal” and part of the turbo mechanism. Sounds a little like BS but that’s what he said.
Can you safely record it? The turbo does make some neat noises - it will sigh, it will make sounds like it's trying to whistle and breath at the same time - but not one that should sound like a growl.
 
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