Having CVT anyone?

"Noisy cabins are weak points in both cars. The Impreza's continously variable transmission tends to hold engine revs high, which amplifies engine noise. But the Mazda is even worse, suffering from conspicuous road noise that drones on the highway."

kaboomie

The problem with comparing the operation of MT with CVT is the fact that CVTs have those variable diameter pullies on the drive and driven shafts, as the following CVT animation shows:

So there goes your earlier comparision of CVT with MT out the window.

Based on that Consumer Report article that seems to be the case. Apparently some computer tries to keep the diameter of the two pullies fairly rigid.

Thanks again for that quote. After my current Accord with pretty annoying road noise I sure would expect something better from my next car.

Well, the corresponding feature is the gears of the MT itself, which are different diameter. Of course, those are done in discrete steps on an MT, rather than continuously.

How do you figure that? The point I was trying to make was that there is a direct non-slipping linkage between the engine and transmission in both cases. Therefore you feel immediate reaction from engine acceleration, and immediate reaction from engine deceleration, aka engine braking.

Well, whether it's some computer controlling the diameter, or some mechanical regulator controlling the diameter, the result is the same, or similar.

Yousuf Khan

Yes, and with MT it takes manual action to do that but until somebody mentioned some paddles here, I didn't know there was a manual method to force a certain gear ratio on CVT to engage engine brake. Had you mentioned that earlier, I would not have brought up the issue.

Never mind. This topic is becoming repetitive and most people have probably tuned out already.

Drove a 2010 CVT Legacy last week down a very steep hill. Used the paddles to take it down to what it considered first gear (displayed as 1 on the dash) while leaving the console shifter in Drive. Engine braked like a champ and I don't think it would've been any noisier than a MT vehicle.

Had I not used the paddles? It would've sailed down the hill with the dash indicator always displaying D and probably not slowed down had I not applied the brakes or crashed into something.

At the end of the hill, I used the paddles to get it up into 2nd or 3rd, but hitting the accelerator will eventually force the CVT to seek out whatever drive ratio it sees fit, essentially ending the manual input of the driver and going back to D.

Bless you, Steve--actual real-world experience!

That's interesting about dashboard display--did it start with "D" or "3" or some such and changed as you geared down?

I'm glad you chose to try the gear-down approach instead. :-) I'm sure that the Legacy appreciated it as well...

Speaking of noise...last time I was coming down the aforementioned grade near Yosemite, the friend who was in my Legacy Wagon with me asked whether the car was okay, because the engine had gotten pretty noisy. I pointed out that it was only going around 4,000 rpm and redline is about 6,500, so although it sounded in some distress, it was fine. :-) Yeah, it's louder at 4K than my Porsche is, but I don't care; I don't do that very often.

Patty

I think I have read of one person that complained about the reduced ability= of the CVT equipped Outback to engine brake down an extreme slope where th= ey lived. It seems to have been only related to the increased engine idle w= hen the car was cold. maybe under that condition, Subaru should consider so= me type of re-programming of the system.

You could ask for feedback from CVT owners at subaruoutback.org or ultimate= subaru.org Forums.

Well, this is the type of feedback I was hoping for, so thanks for that, Steve. So even CVT's need manual intervention with those paddles to engage the engine brake on a long downhill to stay within speed limit. It confirms my original suspicion that a car computer could not possibly know such things. Those paddles are probably acting as some kind of wedges to prevent the drive pullies automatically change the drive ratio that would normally happen during acceleration.

When I think how simpler CVT's are compared to conventional A/Ts, I don't understand why CVTs did not become the "conventional" A/Ts right from the getgo, instead of the way-compex alternatives most cars use today.

Hi Patty. Steve again from Google this time. The dash display is always D unless you intervene with the paddles. Once you do that, it does from 6 to 1, depending on what "gear" you want to be in. Good question about where the display starts once you begin to use the paddles. I didn't pay attention to it in that particular case.

I've not tested the console shifter in its "Auto-Manual" mode, but I suspect it would stay in whatever gear you select, unless you try to go over redline or bog the engine by driving too slowly. In traditional Drive, the CVT will go back into it's normal thing if it doesn't detect further input from the paddles, or you hit the gas or brakes.

That is what I understood the Subie salesman to say when I spoke to him the other day. The car will let you do what you want unless you endanger the engine.

Yep, he mentioned that in relation to downshifting with the paddles on freeway offramps, without putting the gearshift lever into Manual.

Patty

When using the "manual shifter" mode, did the ratios change suddenly like in a real manual, or gradually & smoothly?

Yousuf Khan

"When using the "manual shifter" mode, did the ratios change suddenly like in a real manual, or gradually & smoothly?"

It was sudden, though as I remember it the downshifts were snappier than the upshifts. You could be in first and paddle it up to sixth as fast as you like, but I think it wouldn't automatically go into that top ratio if the vehicle's speed didn't warrant it yet. You'd probably have to be on the gas for all of the upshifts.

Does not remind you of your dentist equipment? (pun intended)

And yes, firewall sound deadening IS expensive as tens of southands of chinese autoworkers deadening firewalls could probably attest by now.

Manual labor mostly I think.

And where the heck is SOA with an eduficational video when there is such a wide area open for speculation? :^)

Steering column shifters were called "three on the tree".

Yep, drove a few myself.

If my dad ever mentioned a 'four on the floor' shifter, he would always smile, wink and add "and a fifth under the seat".

Lol

wink and add "and a fifth under the seat".

What year is your accord to have such a problem with road noise? Is the problem the tires instead?

Kumho Ecsta Plat> >