Why do cars with automatic transmissions have tachometers?

Curious as hell about this.

Was taught by the parents to drive in general on a 65 Chevy with an auto
tranny.

Then the parents taught me to drive a stick on a 67 Dodge 3-on-the-tree
Dart.

None of them had a tach.

I presently drive a 5-speed sedan with a tach but I never notice it as I
shift based on what my ear (and obviously "experience") tells me.

Obviously I understand what the tachometer is for but.....my friends
and relatives various vehicles are universally automatics and almost all
- depending of course on the options they took - have tachometers on
them.

What's the point of the tachometer on a vehicle with an automatic
transmission?

Seriously, based on my understanding of WHY the tachometer exists, why
are there tachs on vehicles with automatic transmissions?

tach's are in cars today for a very simple reason. they make the idiots who
buy and drive them feel "sporty". it has nothing to do with finding the
shift points.a honda civic is a honda civic. but put a tach in it and a big
wing on the back, and it is a CIVIC!!! see? it gots a tach . now i can go
racing cause i gots a race car!!! its got to be one, cause its got a tach in
it!!
"TLittle" > wrote in message
...
>
> Curious as hell about this.
>
> Was taught by the parents to drive in general on a 65 Chevy with an auto
> tranny.
>
> Then the parents taught me to drive a stick on a 67 Dodge 3-on-the-tree
> Dart.
>
> None of them had a tach.
>
> I presently drive a 5-speed sedan with a tach but I never notice it as I
> shift based on what my ear (and obviously "experience") tells me.
>
> Obviously I understand what the tachometer is for but.....my friends
> and relatives various vehicles are universally automatics and almost all
> - depending of course on the options they took - have tachometers on
> them.
>
> What's the point of the tachometer on a vehicle with an automatic
> transmission?
>
> Seriously, based on my understanding of WHY the tachometer exists, why
> are there tachs on vehicles with automatic transmissions?
>
>
>
>

"TLittle" > wrote in message
...
>
> Curious as hell about this.
>
> Was taught by the parents to drive in general on a 65 Chevy with an auto
> tranny.
>
> Then the parents taught me to drive a stick on a 67 Dodge 3-on-the-tree
> Dart.
>
> None of them had a tach.
>
> I presently drive a 5-speed sedan with a tach but I never notice it as I
> shift based on what my ear (and obviously "experience") tells me.
>
> Obviously I understand what the tachometer is for but.....my friends
> and relatives various vehicles are universally automatics and almost all
> - depending of course on the options they took - have tachometers on
> them.
>
> What's the point of the tachometer on a vehicle with an automatic
> transmission?
>
> Seriously, based on my understanding of WHY the tachometer exists, why
> are there tachs on vehicles with automatic transmissions?
>
A tachometer on an automatic transmission vehicle can be very useful,
especially for one that is electronically controlled.

If I want to get the transmission to shift smoothly at something like 3000
rpm in each gear, I can gradually accelerate and then let off the throttle
just a bit as the tachmeter nearly reaches 3000 rpm, at which time, the
transmission will shift at the desired RPM's.

Same goes for if I want the transmission to shift at 2500 RPM's or less
(although that's really slow acceleration generally only used in residential
areas) or at 4000 RPM's or more (climbing a bit of a grade). The accurate
shifts at a given RPM can continue to occur until the transmission reaches
its final gear and torque converter lockup subseqently occurs, thanks to the
visual feedback of the tachometer.

After a while, I've learned the acceleration rates for shifting at a given
RPM, so I can maintain the throttle in a constant position such that the
transmission shifts smoothly at the desired RPM.

Without a tachometer, I could judge by engine sound, but not know the exact
RPM's. And, it's also helpful to know when the engine is approaching redline
under more spritied acceleration (e.g., flooring it on a very short
interstate onramp that merges rather than joins with an extra lane, giving
very little distance to get up to the 65mph freeway speed) rather than just
waiting for the transmission to automatically shift to the next gear when
the engine hits redline.

Since my car's specifications indicate a maximum of 126 horsepower at 5500
RPM, there's really no need to exceed 5500 RPM, but I wouldn't know if I
reached or exceeded that max engine torque RPM under higher acceleration
without a tachometer.

Others may vary in their usage or requirements for a tachometer.

As Tom said, to make you think you got a sporty car.
Useless as an udder on a turtle for most drivers.

Daniel W. Rouse Jr. wrote:
> "TLittle" > wrote in message
> ...
> >
> > Curious as hell about this.
> >
> > Was taught by the parents to drive in general on a 65 Chevy with an auto
> > tranny.
> >
> > Then the parents taught me to drive a stick on a 67 Dodge 3-on-the-tree
> > Dart.
> >
> > None of them had a tach.
> >
> > I presently drive a 5-speed sedan with a tach but I never notice it as I
> > shift based on what my ear (and obviously "experience") tells me.
> >
> > Obviously I understand what the tachometer is for but.....my friends
> > and relatives various vehicles are universally automatics and almost all
> > - depending of course on the options they took - have tachometers on
> > them.
> >
> > What's the point of the tachometer on a vehicle with an automatic
> > transmission?
> >
> > Seriously, based on my understanding of WHY the tachometer exists, why
> > are there tachs on vehicles with automatic transmissions?
> >
> A tachometer on an automatic transmission vehicle can be very useful,
> especially for one that is electronically controlled.
>
> If I want to get the transmission to shift smoothly at something like 3000
> rpm in each gear, I can gradually accelerate and then let off the throttle
> just a bit as the tachmeter nearly reaches 3000 rpm, at which time, the
> transmission will shift at the desired RPM's.
>
> Same goes for if I want the transmission to shift at 2500 RPM's or less
> (although that's really slow acceleration generally only used in residential
> areas) or at 4000 RPM's or more (climbing a bit of a grade). The accurate
> shifts at a given RPM can continue to occur until the transmission reaches
> its final gear and torque converter lockup subseqently occurs, thanks to the
> visual feedback of the tachometer.
>
> After a while, I've learned the acceleration rates for shifting at a given
> RPM, so I can maintain the throttle in a constant position such that the
> transmission shifts smoothly at the desired RPM.
>
> Without a tachometer, I could judge by engine sound, but not know the exact
> RPM's. And, it's also helpful to know when the engine is approaching redline
> under more spritied acceleration (e.g., flooring it on a very short
> interstate onramp that merges rather than joins with an extra lane, giving
> very little distance to get up to the 65mph freeway speed) rather than just
> waiting for the transmission to automatically shift to the next gear when
> the engine hits redline.
>
> Since my car's specifications indicate a maximum of 126 horsepower at 5500
> RPM, there's really no need to exceed 5500 RPM, but I wouldn't know if I
> reached or exceeded that max engine torque RPM under higher acceleration
> without a tachometer.
>
> Others may vary in their usage or requirements for a tachometer.

Same here. I use mine all the time for forcing up-shifts and as a
general check on engine performance. Example: Hmmm...last month I was
climbing this hill in 6th (od), what happened that I am now in 5th?. I
can't feel or hear the diffeence in the 6/5 or 5/6 shift so see of the
pants is no indicator.

Harry K

TLittle > wrote in :

>
> Curious as hell about this.
>
> Was taught by the parents to drive in general on a 65 Chevy with an
auto
> tranny.
>
> Then the parents taught me to drive a stick on a 67 Dodge 3-on-the-tree
> Dart.
>
> None of them had a tach.
>
> I presently drive a 5-speed sedan with a tach but I never notice it as
I
> shift based on what my ear (and obviously "experience") tells me.
>
> Obviously I understand what the tachometer is for but.....my friends
> and relatives various vehicles are universally automatics and almost
all
> - depending of course on the options they took - have tachometers on
> them.
>
> What's the point of the tachometer on a vehicle with an automatic
> transmission?
>
> Seriously, based on my understanding of WHY the tachometer exists, why
> are there tachs on vehicles with automatic transmissions?
>
>
>
>

ive found factory tach's handy in diag. some questionable tranny shift
probs.without having to hook up the scanner...shift points, shift slip,
etc....i think your first RE; had it pegged, just another 'do-dad' like
auto vol. control and steering wheel radio controls....as much as they
say there cars are values they sure spend alot of time and money on crap
thats not needed.........................kjun

wrote:
>
> As Tom said, to make you think you got a sporty car.
> Useless as an udder on a turtle for most drivers.

I found it useful to diagnose a TCC problem in my X-car,
I could easily see what RPMs the clutch locked up and
unlocked, and when I noticed that it wasn't locking and
unlocking at the proper RPMs for the conditions I knew
something was up. Sure enough, a few thousand miles later
it failed, but thanks to the tach I had plenty of warning
and was prepared to immediately repair the problem.

JazzMan
--
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On Sun, 18 Sep 2005 07:52:40 GMT TLittle > wrote:

> What's the point of the tachometer on a vehicle with an automatic
> transmission?

To use current-day terminology: it's "bling".

--
remove MYSHOES to email

> Curious as hell about this.

Because it's nice to know when your getting ready to "redline" when you have
your foot all the way to the floor.

"tom" > wrote in message
...

(****ing idiot text snipped)

I drive in Montana. It's nice to know when I'm approaching redline on the
tach when I have my foot to the floor.