SkyActiv 6spd AT - shudder

[erik]

Hi all. Picked up my new 2012 SkyActiv hatch less than 2 weeks ago and have about 500km on it now. Totally loving the car. This is my first automatic and it is taking me a bit of time to get used to daily 1-footed driving. I have noticed a slight shudder that I don't remember experiencing on the SkyActiv unit I test drove. When I put the car in Drive, the transmission engages normally and will creep as soon as I take my foot off the brake. The "problem" occurs in normal stop & go driving. When I come to a full stop and then lift my foot off the brake to start moving again, there is a slight hesitation before the car moves accompanied by a minor but perceptible shudder. The tach also drops *very* slightly when the shudder is felt. If I am sitting at a red light and move the shifter over to the manual gate, it will shudder and then creep normally when I take my foot off the brake. I have never felt this in any auto-equipped Mazda before, so I am wondering if this is just part of this car's personality or if there is an actual problem with it.

I should also mention that upshifts and downshifts while driving are smooth, but that I do feel the transmission downshift as I come to a complete stop. I realize this isn't an conventional auto tranny and any additional insight you guys may have is appreciated!

[krimsalt]

It honestly sounds fine. It's a new car so let it wear-in. Plus if you're not used to automatics you will find that odd feeling considering the transmission is always engaged.

The only thing wrong with it that I can see is the fact that it is an automatic :chuckle

[Wes08M3]

From what I have heard, the skyactiv autos go into neutral when the car is idling. So the shudder your are feeling when you release the brake from a stop could be the transmission engaging first gear.

Not sure if the shudder is a normal feeling for these cars as I have yet to drive one. Maybe someone with more experience with the skyactiv can chime in.

Also, from other posts, I think it's normal to feel it downshift when slowing down.

[zoomahh]

+1
About the first 1000 k's it would do a hard downshift when going from 4 to 3.. That is to say, when I'm approaching a red light or coming to a corner, or coming to a redlight. As soon as it got past that mark..... Nadda... Shifts smooth as a baby's butt from then on and no problems since. Chalk it up to your cars breaking in. Remember it's only got 500 k on her. If after 1000 it's still buggin.... Bring her in and tell them about it. That's their job....to fix it ;)

Also, someone mentioned about when the car is stopped it goes into neutral.. I can see that. Because when I let off the brake in traffic, I can also feel as if I just put it into gear...it's all good.

[krimsalt]

^^ It never disengages into neutral, because even if you LIGHTLY lift your foot from the brakes, the car slowly pulls forward. It's always in gear

[zoomahh]

Well... Whatever it is.... I feel a diff from my 07 3 GS I had before. Something is diff from that one to this one. Whatever it is, it's givin me great gas mileage. I think I'm gonna hit 6.5 / 100km on my next fillup. I'm creepin up on 300 km and it hasn't come off full yet :D

[JHX 1138]

According to either Car and Driver or Motor Trend, the SkyActiv auto uses a torque converter for all speeds equal to or below 8mph. Above that speed it uses a "DSG-like" tranny-thingy. The point is, there is a switchover point between torque-converter-based tranny and fancy-schmancy tranny, and that crossover point is 8mph. You should check and see at what speed you noticed the "shudder"... was it 8mph (13 km/h)?

[dambay]

^^ It never disengages into neutral, because even if you LIGHTLY lift your foot from the brakes, the car slowly pulls forward. It's always in gear

It definitely does switch into neutral when stopped. Its not every time that you come to a complete stop, but the shudder the OP is feeling is definitely from that.

[dambay]

According to either Car and Driver or Motor Trend, the SkyActiv auto uses a torque converter for all speeds equal to or below 8mph. Above that speed it uses a "DSG-like" tranny-thingy. The point is, there is a switchover point between torque-converter-based tranny and fancy-schmancy tranny, and that crossover point is 8mph. You should check and see at what speed you noticed the "shudder"... was it 8mph (13 km/h)?

That's right, the torque converter is used at speeds below 20km/h, above which lockup occurs, which prevents (or reduces) the losses associated with a torque converter.
Also of interest, is the skyactivs delay ignition timing on cold start to heat the catalytic converter, so it can do its thing and reduces emissions. That's why the car idles so much higher/louder initially for about ten seconds, after which it quiets right down.

[Cosmo77]

I can confirm that the transmission will shift into neutral when you come to a stop. It is almost impossible to feel the shift into gear, how ever I have heard of some cars where you can feel it engadge.

[dambay]

Yeah, and as others have stated, you may notice it more since the car is so new, and you may occasionally notice it from time to time even after you've driven it more, but it does improve.

[erik]

Thanks for the reassurance guys! I'll try to keep the obsessing to a minimum until she's adequately broken in.

Does it shift into neutral after a certain time being fully stopped? Or is it a function of a bunch of factors I probably wouldn't be able to make sense of?

[dambay]

I don't think it's a set amount of time before the car switches into neutral. Its seems somewhat random for me. Either that, or it does it so smoothly that I can't tell anymore. But occasionally its noticeable for me.

[zoomahh]

All I know is I just LUV my new SkyActiv :D

[dambay]

All I know is I just LUV my new SkyActiv :D

+1

[slam525i]

Thanks for the reassurance guys! I'll try to keep the obsessing to a minimum until she's adequately broken in.

Does it shift into neutral after a certain time being fully stopped? Or is it a function of a bunch of factors I probably wouldn't be able to make sense of?

Okay. I just spent like 10 minutes reading up on the SkyActiv tranny. Very interesting.

So, first of all, it does not neutral by itself. That's not how automatics work, and it's not how this SkyActiv thing works.

In first gear, it's a regular automatic, but with a very low-speed lock up. Basically, as soon as you're moving, it'll lock up the torque converter. That is what you feel when it shudders, as locking up the torque converter forces the engine to drop in RPM a little (no more "slippage" between the engine and gearbox). All cars lock their torque converters, but usually at a higher speed, thus higher inertia, thus less felt by the driver. From that speed onwards, the torque converter stays locked, and you can consider the car to be a regular, dual-clutch automatic gearbox. Pretty cool right? None of the stupid, jerky starts as with every other dual-clutch because of the torque converter, but all the benefits of a dual-clutch. (i.e. you get to avoid being this guy: http://jalopnik.com/5880847/watch-a-17-million-aston-martin-one+77-repeatedly-stall-on-the-street)

It's fricking ingenious if you ask me. It's such a simple concept that I'm surprised no one else did it first.

[dambay]

Okay. I just spent like 10 minutes reading up on the SkyActiv tranny. Very interesting.

So, first of all, it does not neutral by itself. That's not how automatics work, and it's not how this SkyActiv thing works.

In first gear, it's a regular automatic, but with a very low-speed lock up. Basically, as soon as you're moving, it'll lock up the torque converter. That is what you feel when it shudders, as locking up the torque converter forces the engine to drop in RPM a little (no more "slippage" between the engine and gearbox). All cars lock their torque converters, but usually at a higher speed, thus higher inertia, thus less felt by the driver. From that speed onwards, the torque converter stays locked, and you can consider the car to be a regular, dual-clutch automatic gearbox. Pretty cool right? None of the stupid, jerky starts as with every other dual-clutch because of the torque converter, but all the benefits of a dual-clutch. (i.e. you get to avoid being this guy: http://jalopnik.com/5880847/watch-a-17-million-aston-martin-one+77-repeatedly-stall-on-the-street)

It's fricking ingenious if you ask me. It's such a simple concept that I'm surprised no one else did it first.

It DOES switch into neutral when you come to a stop. Everything else you said is correct, but the transmission switching into netral while stopped is also true. Its one of the fuel saving features in the Skyactiv powertrain. By disengaging the engine from th rest of the drive train, the engine doesn't have to work as hard when it doesn't have to (i.e. a complete stop). The OP is talking about shudder felt when he begins driving from a complete stop. You're right about the different speeds with the Skyactiv Torque Converter though. Typically a car will lockup the torque converter at higher speeds, but to further improve fuel economy, the Skyactiv torque converter will lockup at speeds above 20 km/h.

Torque Converters with lockup clutches have been around for a long time, but when they were originally introduced they were simply too expensive and complex to be practical in most cars. its only in the last 40 or so years that they reappeared, as demand for fuel efficient cars increased, and are in virtually every automatic car today. It really is an awesome technology.

[JHX 1138]

Is it written somewhere that it switches to neutral at a full stop? If so the car will roll backwards/forwards if you're on a hill incline/decline and let go of the brakes... just like a MT car...

[beyond]

Autoblog just released their review of the 3's SkyActiv...gives a pretty good review of the auto tranny too...

http://ca.autoblog.com/2012/05/17/2012-mazda3-skyactiv-review/#continued

FYI :)

[dambay]

Is it written somewhere that it switches to neutral at a full stop? If so the car will roll backwards/forwards if you're on a hill incline/decline and let go of the brakes... just like a MT car...

The car switches into neutral when the brake is applied at a full stop, and switches back into gear when you remove your foot from the brake...as has been stated a couple times in the posts above.


When I come to a full stop and then lift my foot off the brake to start moving again, there is a slight hesitation before the car moves accompanied by a minor but perceptible shudder.


From what I have heard, the skyactiv autos go into neutral when the car is idling. So the shudder your are feeling when you release the brake from a stop could be the transmission engaging first gear.

[Aitch]

Autoblog just released their review of the 3's SkyActiv...gives a pretty good review of the auto tranny too...

http://ca.autoblog.com/2012/05/17/2012-mazda3-skyactiv-review/#continued

FYI :)

Except for the fact they led off the story by stating the 3 only got the Skyactiv engine AFTER the CX5 arrival, which is completely backwards.

[beyond]

Except for the fact they led off the story by stating the 3 only got the Skyactiv engine AFTER the CX5 arrival, which is completely backwards.

The dudes @ Autoblog have been smoking I guess lol

[dambay]

The dudes @ Autoblog have been smoking I guess lol

Hahaha, crazy bastards. So the torque converter is only used below 8km/h, not 20 like I had stated.

[paraug]

All I know is I just LUV my new SkyActiv :D
+1