Ferrari Mailing List: Re: Fw: Fw: NFC AT ALL!!! Automatic shifting in a GM

[Hans E. Hansen (FList]

Best advice:  Ignor the previous comments below.

GM trannies in the last decade or so very rarely "hunt".  Load
conditions have to be just right  (or wrong, as the case may
be.)  Older cars, OTOH, do have a significant problem when
climbing moderate hills, etc.

While it's true that GM trans will lock and unlock the converter
in completely different circumstances than other brands, shifting
manually between 3rd and 4th does not affect this. Manually putting
it in 3rd will still result in it locking during cruise and unlocking
during coast and accelerate.

Unlocking during acceleration results in somewhat more torque
multiplication, giving marginally better acceleration.  Unlocking
during coast I believe is done mostly for emissions.  It does
result in less engine braking, which is probably the biggest
disadvantage.

But trans wear and tear is NOT affected by manually shifting.

Hans.



On 6/17/08, jimshadow [at] verizon.net <jimshadow [at] verizon.net> wrote:
> >From ListLurker Chuck...
>
> FWIW, YMMV
>
> Jim
> Sent from my BlackBerry(R) wireless device
>
> -----Original Message-----
> From: cmidgett [at] inkonit.com
>
> Date: Tue, 17 Jun 2008 12:57:07
> To:jimshadow [at] verizon.net
> Subject: Re: Fw: [Ferrari] NFC AT ALL!!!  Automatic shifting in a GM
>
>
> There may be *some* truth in it.
> A GM transmission likes to hunt a lot.  If you're right on the edge, it will 
> shift from 3rd to 4th and back and forth.
> My Acura will lock up the convertor around that speed.  If you are going 55 
> and lift off the gas, it stays locked.  When you reapply, unless you give it 
> MORE gas, it stays locked.  A GM on the other hand, will disengage the 
> converter when you lift, lock again after you reapply the gas, then back and 
> forth.  In traffic on the highway, I think it's quit annoying.
> Some GM transmissions (later ones) lock up in 3rd as well, so their theory 
> wouldn't apply.
> But with the '86, it would keep the lockup from occurring until after 45.  
> But you also keep it out of 4th, which would use more gas.
> The best advice is this:  Don't buy a GM.
>
>
>
>
>
>
>  jimshadow [at] verizon.net
> 06/17/2008 12:39 PM
>
> Please respond to
>  jimshadow [at] verizon.net
>
>
> To "cmidgett [at] inkonit.com" <cmidgett [at] inkonit.com>
>
> cc
>
> Subject Fw: [Ferrari] NFC AT ALL!!!  Automatic shifting in a GM
>
>
>
>
>
> Thoughts??
>  Sent from my BlackBerry(R) wireless device
>
>  -----Original Message-----
>  From: LtWacko [at] aol.com
>
>  Date: Tue, 17 Jun 2008 16:11:57
>  To:JIM <jimshadow [at] verizon.net>
>  Cc:The FerrariList <ferrari [at] ferrarilist.com>
>  Subject: [Ferrari] NFC AT ALL!!!  Automatic shifting in a GM
>
>
>  Again, NO Ferrari content but I figured I could get an answer from you
>  guys...
>
>  I was riding in a 1996 Bonneville with a female friend.  While  driving, she
>  would start in "D".  When we got up to speed (45mph), she  would "shift" the
>  car into "D overdrive".  I said "what are you  doing?"  She said her 
> long-time
>  former ex-boyfriend said that it will make  the transmission last longer.  
> Now
>  if it had been any other person, I would  have my doubts.  Her ex-boyfriend
>  is one hell of a driver.  Corvette  enthusiast/hobby racer and the ENTIRE
>  family was seriously involved with  the SCCA.  So, he's a car guy and it 
> makes me
>  wonder if there is any truth  or what are the origins of his advice.
>
>  I can sort of see some of the logic.  In the city, keeping it out of
>  overdrive keeps the torque convertor from locking up at 45 mph and shifting 
> in  and
>  out of it.  Is that any good?  Bad?  More harm in shifting it  yourself?
>  Applies to GM transmissions only?  I vaguely remember this  advice being 
> popular in
>  the early eighties, but I was a puppy then....   okay, not quite .
>
>  So guys, what do you think?
>
>  Thanks.
>
>  Rodney
>
>
>
>  **************Gas prices getting you down? Search AOL Autos for
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