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Discussion Starter · #1 · (Edited)
Let's talk about the chirp...

Here's why your Subaru Ascent chirps when shifting out of park.

"...the CVT (filling) up both primary and secondary pulleys (causes) this chirping noise and at times a surging until pressure equalizes. Noise is considered normal."

That's from a 2016 post regarding the TR690 in an Outback 3.6r. You'll find similar posts in various forums for the Outback 3.6R, Forester XT and WRX, which all use a TR690 series CVT.

To avoid it, give your car a minute or so to warm up.

Because everyone's conditions are a little different, some people may never experience it, some will.

 

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I like this thread already.

Pro-Active, not reactionary to a "problem".

These are machines after all, our levels of expectation based on $'s spent sometimes needs a reality check. Jump back into a 1984 Plymouth Reliant Wagon and get back to me regarding expectations vs $'s spent. Many may not know what a 1984 Reliant wagon is. Consider yourselves lucky.
 

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Thanks for the video example of the sound and reference :thumbsup:. We get our Ascent next month and this is definitely something that would freak the wife out and even me if I heard it. I will say as someone who grew up around construction it sounds more like a wheel grinder than a "chirp" to me :lol: Makes sense since CVTs have a steel belt and pulleys in them. In general, sounds like it's just best to give the car (transmission) a moment to warm up and get the fluid distributed.
 

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I’m guilty
I quick shift often

I’ve never noticed the chirp before, but now I’ll have to specifically listen for it. Maybe it’s because it HASNT GOTTEN COLD in VA in the last year, or maybe I subconsciously expected it and ignored it as normal. Sorry, I’m still bitter that I didn’t get to drive in any snow last winter ?
 

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Discussion Starter · #5 ·
Thanks for the video example of the sound and reference :thumbsup:. We get our Ascent next month and this is definitely something that would freak the wife out and even me if I heard it. I will say as someone who grew up around construction it sounds more like a wheel grinder than a "chirp" to me :lol: Makes sense since CVTs have a steel belt and pulleys in them. In general, sounds like it's just best to give the car (transmission) a moment to warm up and get the fluid distributed.
Alas, it's a big multi-layer chain. Subaru has never used belts in the Lineartronics. That's JATCO who uses steel belts. I am pretty sure it's valves opening to surge fill the pulleys. It's a sound very common to some hydraulic systems I've used. And, since parts of the high pressure assemblies in the CVT hit 1,200 psi, you can imagine exactly how it'd make such a sound as a valve opens and redirects pressure to surge fill a pulley.

Anyway, yes, many people never stop to realize that even on a 90° day, car engines (and their transmissions) are started cold. The Subaru engine (and I think CVT) has a minimum temperature threshold of 165°, and a normal operating temperature of around 195°. The CVT operates between 180-217° (plus a bit under harsher conditions such as towing).

 

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Let's talk about the chirp...

Here's why your Subaru Ascent chirps when shifting out of park.

"...the CVT (filling) up both primary and secondary pulleys (causes) this chirping noise and at times a surging until pressure equalizes. Noise is considered normal."

That's from a 2016 post regarding the TR690 in an Outback 3.6r. You'll find similar posts in various forums for the Outback 3.6R, Forester XT and WRX, which all use a TR690 series CVT.

To avoid it, give your car a minute or so to warm up.

Because everyone's conditions are a little different, some people may never experience it, some will.

https://www.youtube.com/watch?v=P0-HAw8mAc0
Thank you Robert for the folks that are concerned and will feel there is not a problem. I do have 2 questions . One, why doesn't the TR- 580 do this and two why does the TR- 690 at least in my Ascent sound like a bad PS pump even when warm?
 

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Discussion Starter · #8 · (Edited)
Thoughts and answers and thoughts...

Thank you Robert for the folks that are concerned and will feel there is not a problem. I do have 2 questions . One, why doesn't the TR- 580 do this and two why does the TR- 690 at least in my Ascent sound like a bad PS pump even when warm?
Hi GHP,

Let's see if I can tackle these - especially glad you brought these up, since I've seen this question in the OB, Leggy and Foz forums as well. I should have addressed them earlier.

  1. The TR580 and TR690 are quite different in some design components, including how the forward/reverse gear works, the torque converter lock, etc. So, with power and pressure being transferred to the pulleys differently, the results are different. Also, keep in mind, pulley sizes and distance are also different. Pumping up a different pulley is... well... different.
  2. It's not quite "warm" that's the issue. It's whether or not pressure has equalized. If the CVT is "warm", it is less likely to happen, because the pressure *may* have recently equalized.


The valve body is also different. I would EXPECT the pressure in the CVTs is also different, with our high torque one requiring higher pressure, causing different sounds (but I am not digging through the diag docs to find the exact pressure differences - it just makes sense).

A few other notes:
  • Shifting quick from reverse to forward (or vice versa) while the car still has any rolling momentum or any part of the drive train (eg: axle shafts or drive shaft) is still in motion may cause the chirp as pressure rapidly changes between pulleys. That's user error. Absolutely zero automatics, whether geared, or chain driven pulley CVT, or belt driven pulley CVT, or planetary gear based CVT, are supposed to be rapid shifted from forward to reverse or vice versa under such conditions.
  • The CVT's operating temperature is 185°+, with a max temp of up to 243°F (non-inclusive). So, when we turn on our Ascents, or drive to the store 5 blocks away, the CVT is actually cold, even though it may be what we would consider a blistering 140°F.

On an anecdotal tangential note, I used to own an ancient hydraulic paper cutter. It would slice through a phone book like a hot knife would slice through melted butter. It was built in the 1930s, and worked to the day I got rid of it in 2005. Making the valves that controlled pressure to the massive knife open or close at a certain speed or open or close to a certain partially opened point would make a similar sound (sans the muffling of a CVT case around the valves, which changes the sound slightly). It was the bigger version of this beast, and weighed about a ton with pump, tank, and its monstrous steel frame and deck.



 

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Thanks Robert! Very detailed explanation. Would you think the 2020 OB'S cvt would be identical to the Ascent or different. Towing is 3500 vs 5000 but I assume thats due to the more robust SGP frame for the Ascent
 

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Discussion Starter · #10 ·
Thanks Robert! Very detailed explanation. Would you think the 2020 OB'S cvt would be identical to the Ascent or different. Towing is 3500 vs 5000 but I assume thats due to the more robust SGP frame for the Ascent
I suspect that the OB 2.5 will continue to use the TR580. And I have never heard of any high torque Subaru NOT using the TR690, so, I fully expect that both the 2020 Leggy and OB 2.4DIT will use the TR690.
 

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I have also started to experience this chirp. Thanks Robert for the explanation...have a few follow on queries:
Initially during the first 600 miles or so I didnt have the chirp, then it started off randomly and now its there always...is this to be concerned about? My driving patterns haven't changed even slightly during the past 1500 miles.

Also, here is my other concern: I start the car, let it idle for a few seconds and then put it in reverse (no chirp yet). Then stop, shift into drive and this is when I get the chirp (in other words it does not happen during the first shift when the trans is cold, but during the first time I shift into D).
Lastly, the chirp used to come only when the car was sitting overnight, but recently its also starting when I let the car sit for an hour or two...
Not sure if these are also normal behaviors or if it should be checked out...
Thanks as always!
 

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Also, here is my other concern: I start the car, let it idle for a few seconds and then put it in reverse (no chirp yet). Then stop, shift into drive and this is when I get the chirp (in other words it does not happen during the first shift when the trans is cold, but during the first time I shift into D).
Lastly, the chirp used to come only when the car was sitting overnight, but recently its also starting when I let the car sit for an hour or two...
Not sure if these are also normal behaviors or if it should be checked out...
What you described has been exactly my experience for the past 10,000 miles+ and I'm pretty sure it is nothing to be concerned about.
 

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I suspect that the OB 2.5 will continue to use the TR580. And I have never heard of any high torque Subaru NOT using the TR690, so, I fully expect that both the 2020 Leggy and OB 2.4DIT will use the TR690.
Do we know what the 2020 Legacy/Outback "do" use?
 

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Discussion Starter · #14 ·
Do we know what the 2020 Legacy/Outback "do" use?
Yes.
Since 2012/2013, ALL high torque engine/CVT combos have been the TR690.

All other CVTs have been the TR580.

So, the Outback XT, for instance, uses the TR690, and the Outback 2.5i uses the TR580.
 

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Also, here is my other concern: I start the car, let it idle for a few seconds and then put it in reverse (no chirp yet). Then stop, shift into drive and this is when I get the chirp (in other words it does not happen during the first shift when the trans is cold, but during the first time I shift into D).
Lastly, the chirp used to come only when the car was sitting overnight, but recently its also starting when I let the car sit for an hour or two...
Not sure if these are also normal behaviors or if it should be checked out...
Thanks as always!
Greetings,
My chirp also started after a few hundred miles and happens when entering Drive. It also happens regardless of how long I let the car run before shifting. Lastly, it happens most of the time, day or night as long as the car was off for more than a few minutes. As far as I know, it's not a problem. At least, that's what people say who know better than I. :)
 

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Discussion Starter · #17 ·
MIne chirps every morning...i could sit there for 30 seconds and it doesn't matter.
57,000 miles and mine still chirps. :)

Drive it and it won't chirp again until next time you start after it's been sitting for a bit.
 

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Meant to mention when the car is cold. Once its up to temp it won't do it anymore. But when its cold...every time.
57,000 miles and mine still chirps. :)

Drive it and it won't chirp again until next time you start after it's been sitting for a bit.
 

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Discussion Starter · #19 ·
Meant to mention when the car is cold. Once its up to temp it won't do it anymore. But when its cold...every time.
I always thought that was an an interesting thing about high pressure hydraulics. I kinda like the sound, but, maybe it's just grown on me, LOL!!! :ROFLMAO:
 

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I've never heard mine chirp. But then again I'm in Phoenix with a much higher average temp and it's always in the a garage so it's warm to hot.

Half the year my engine/trans is above 90F when I start it :D
 
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