# 2011 1LT Auto Hard Shifting, 70 MPH RPM=3000



## SilverCruzer (Nov 30, 2010)

smitty2point0 said:


> My issue is that the shifting doesn't occur until around 4 grand on the vehicle, when taking off with a "light" foot, the downshifts are rather awkward also. Don't get me wrong, the car will fly if I need it too, it's very peppy. The cruising on the interstate is also weird. Isn't 3 grand @ 70mph pretty high? I know I'm moving from totally different animal (avalanche), but it seems a bit high. Plus I'm comparing to my wife's new Altima (i know, i know). She switched from a hummer and her new car drives like a dang golf cart. I NEVER feel it shift and it's barely rotating @ 70mph. I know it's a different class of car, but they both have 4 cylinders.


70 mph usually is around 2600 RPM for most of us. The size of the 4 cyl in the Altima and other mid-size sedans is bigger, up to one liter bigger, so it can cruise at 70 mph with slower engine speeds. You will find out soon enough that this also means getting the EPA mileage won't always happen at 70 mph either. Welcome to the debate.

The shifting - does it the 4 grand situation happen when engine is cold and warm?


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## 70AARCUDA (Nov 14, 2010)

...the Cruzes' 6-speed GM 6T40 HydraMatic (RPO: MH8) transmissions' 6th gear-ratio is 0.746:1 and its' axle-ratio is 3.87:1, which makes the "final" ratio (ie: gear x axle) a rather "high" 2.887:1 (~25.9 mph/1,000 rpm), which means the engine speed will be 2,701 rpm at 70 mph.


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## smitty2point0 (Mar 24, 2011)

that's about right...I was being approximate on the 3000RPM. My apolgies. I'm not certain about the cold warm thing. I'm positive it happens not matter what. However this afternoon after driving around for a while, I did notice it wasn't AS noticable, however it still seemed a little high rev'd while shifting. Maybe it's because it's been a while since I've had a 4 cylinder or even paid attention to these things. Do you think it's worth the service man to even look at it? 

From what I'm reading, I can't imagine a new 2011 would need a flash update on the TCM...but I guess you never can tell.


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## montgom626 (Jan 16, 2011)

70AARCUDA said:


> ...the Cruzes' 6-speed GM 6T40 HydraMatic (RPO: MH8) transmissions' 6th gear-ratio is 0.746:1 and its' axle-ratio is 3.87:1, which makes the "final" ratio (ie: gear x axle) a ratio "high" 2.887:1 (~25.9 mph/1,000 rpm), which means the engine speed will be 2,701 rpm at 70 mph.


Good information. What is the rpm for the ECO with a manual transmission at 70 mph?


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## montgom626 (Jan 16, 2011)

SilverCruzer said:


> You will find out soon enough that this also means getting the EPA mileage won't always happen at 70 mph either. Welcome to the debate.


EPA testing is done at around 60 mph, so that is another reason running at 70 mph won't get you the EPA mileage rating.


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## slyedog (Mar 17, 2011)

The Altima has a CVT so you not feel any shift unless you manual shift. I don't drive our Cruze as much as my wife but the trans seems to shift fine even though our vin is in the tsb list. I'll wait till we have a few thousand on it before I worry any. Give it time to learn.


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## 70AARCUDA (Nov 14, 2010)

montgom626 said:


> Good information. What is the rpm for the ECO with a manual transmission at 70 mph?


...read for yourself:

*http://www.epa.gov/otaq/datafiles/FOI_BGMXV01.8011_APPIPT1_R1.PDF*

...what you're looking for is in the table of data on page 26, 86.1844(d)(12).


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## montgom626 (Jan 16, 2011)

70AARCUDA said:


> ...read for yourself:
> 
> *http://www.epa.gov/otaq/datafiles/FOI_BGMXV01.8011_APPIPT1_R1.PDF*
> 
> ...what you're looking for is in the table of data on page 26, 86.1844(d)(12).


UR killing me


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## montgom626 (Jan 16, 2011)

70AARCUDA said:


> ...read for yourself:
> 
> *http://www.epa.gov/otaq/datafiles/FOI_BGMXV01.8011_APPIPT1_R1.PDF*
> 
> ...what you're looking for is in the table of data on page 26, 86.1844(d)(12).


I looked and for the life of me, I cannot figure it out


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## 70AARCUDA (Nov 14, 2010)

...at the junction of column *N/V* and the row *CRUZE ECO* with *M6*/4 transmission is the number *30.8*, This (N/V) number indicates that the engine turns-over 30.8 revolutions (*N*) at the EPA "standard test" speed of *50 MPH* (*V*).

...note that N/V = 30.8-31.3 for Eco M6 models depending upon rim/tire sizes:

• P215/55R17 ALS GDY - N/V = 30.8
• P215/60R16 ALS FIR - N/V = 31.0
• P225/45R18 AL3 MIC - N/V = 31.2
• P225/50R17 AL3 CON - N/V = 31.3

...for our 1.4LT A6 models, N/V = 38.5-38.8 depending upon rim/tire sizes:

• P215/60R16 ALS GDY - N/V = 38.5
• P225/45R18 AL3 MIC - N/V = 38.8
• P225/50R17 AL3 CON - N/V = 38.8

...lots of hidden information there; you just gotta "dig" for it!


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