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G

·
Discussion Starter · #2 ·
No, very little difference at all; overdrive will increase gas mileage, but
the effects will be the greatest at highway speeds. Think lower engine
rpm=best economy. By the way, there is nothing to gain by cancelling
overdrive operation in town, this is why it is enabled by default with every
key cycle.
"Paul O." <[email protected]> wrote in message
news:[email protected]
> Just curious, I have never used overdrive in town, but have been wondering
> if it makes any difference in gas mileage to speak of? Thanks.
>
> --
> Paul O.
> [email protected]
>
 
G

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Discussion Starter · #3 ·
Errmmm, some transmissions (the A4LD comes to mind) will "hunt" under
certain urban driving conditions.... newer transmissions "generally" avoid
this through electronic strategy.... older transmissions depending on
mechanical indications are hardest hit.

Both the A4LD and the AOT could fall prey to the extra stresses, heat and
wear associated with the condition. When offering advice, we should always
strive to err on the side of safety.


"Ted" <[email protected]> wrote in message
news:eek:[email protected]
> No, very little difference at all; overdrive will increase gas mileage,
> but the effects will be the greatest at highway speeds. Think lower
> engine rpm=best economy. By the way, there is nothing to gain by
> cancelling overdrive operation in town, this is why it is enabled by
> default with every key cycle.
> "Paul O." <[email protected]> wrote in message
> news:[email protected]
>> Just curious, I have never used overdrive in town, but have been
>> wondering if it makes any difference in gas mileage to speak of? Thanks.
>>
>> --
>> Paul O.
>> [email protected]
>>

>
>
 
G

·
Discussion Starter · #4 ·
Jim, the overdrive on the A4LD and AOD are an integral part of the trans,
and therefore shifting in or out of overdrive was no different than any
other gear; automatics were designed to shift up and down. The real problem
was that the calibration of the engine controls had not yet reached the
level to allow high load combined with low rpm, which resulted in many
driveability concerns, including shift hunting. Fortunately, that is in the
distant past now. The fact is, that in city driving, the overdrive does
nothing for fuel economy, and that was the question that I hoped I answered
for the poster. As for whether or not you could acutally harm the
transmission, that debate could rage on forever, but I have never seen any
hard evidence of it, so let's not muddy the waters here, ok?
"Jim Warman" <[email protected]> wrote in message
news:lSWCf.131155$AP5.171[email protected]
> Errmmm, some transmissions (the A4LD comes to mind) will "hunt" under
> certain urban driving conditions.... newer transmissions "generally" avoid
> this through electronic strategy.... older transmissions depending on
> mechanical indications are hardest hit.
>
> Both the A4LD and the AOT could fall prey to the extra stresses, heat and
> wear associated with the condition. When offering advice, we should always
> strive to err on the side of safety.
>
>
> "Ted" <[email protected]> wrote in message
> news:eek:[email protected]
>> No, very little difference at all; overdrive will increase gas mileage,
>> but the effects will be the greatest at highway speeds. Think lower
>> engine rpm=best economy. By the way, there is nothing to gain by
>> cancelling overdrive operation in town, this is why it is enabled by
>> default with every key cycle.
>> "Paul O." <[email protected]> wrote in message
>> news:[email protected]
>>> Just curious, I have never used overdrive in town, but have been
>>> wondering if it makes any difference in gas mileage to speak of? Thanks.
>>>
>>> --
>>> Paul O.
>>> [email protected]
>>>

>>
>>

>
>
 
G

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Discussion Starter · #5 ·
I don't believe I was making any waters muddy.... This NG encomapsses folks
from all walks of life... including thse that are driving old technology....
not because they want to but because that's what they can afford.

Additionally, I see no debate.... early overdrive transmissions had concerns
with the overdrive function. Since torque is reduced through the use of
overdrive, these components were often constructed of lighter material or
less substantial amounts of materials. Hunting between direct and overdrive
has killed many A4LDs and AOTs.

Your advice would lead those with these older units to believe that OD is OK
in urban use, quite possibly causing them financial burdens they can ill
afford.

Are automatics designed to shift up and down??? Of course..... Does a
certain amount of wear occur with each shift? Yes.... Will a "hunting"
condition increase this wear? Yes... The transmission is chock full of
sacrificial parts... if there is an action that someone can take to increase
the life span of these parts, it should be made known.

I have no idea where you are going with the "overdrive on the A4LD and AOD
are an integral part of the trans".... Of course this function is part and
parcel of the transmission assembly..... How could it be otherwise? Even
though this function is "integral" to the transmission, it does not follow
that the function should either be used or allowed to operate at all
times... especially when we deal with older technology.

Rather than offer a blanket "fugedaboudit" statement, these people deserve
to know that there have been historical concerns with OD function in urban
use. They are intelligent enough to form their own opinions as to whether
they want to allow OD function or not. If they decide to cancel OD, it is
their choice and, as I had stated. if we are to make an "error", our error
should save us money... not cost us money.

Now... getting back to your statement about the calibration of the engine
controls..... On both the A4LD and the AOT the only "engine control" I can
think of involved torque coverter lock. Overdrive function depended largely
on either a vacuum modulator (for engine load sense) or a throttle valve
cable (again for engine load sense). Where, in Gods name, does PCM
calibration enter the picture?

Remember, in this venue, the past is not so distant and decent advice for
one reader is terrible advice for another.
 
G

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Discussion Starter · #6 ·
"Jim Warman" <[email protected]> wrote:


> Your advice would lead those with these older units to believe that OD
> is OK in urban use, quite possibly causing them financial burdens they
> can ill afford.
>
> Are automatics designed to shift up and down??? Of course..... Does a
> certain amount of wear occur with each shift? Yes.... Will a "hunting"
> condition increase this wear? Yes... The transmission is chock full of
> sacrificial parts... if there is an action that someone can take to
> increase the life span of these parts, it should be made known.
>
>
> Rather than offer a blanket "fugedaboudit" statement, these people
> deserve to know that there have been historical concerns with OD
> function in urban use. They are intelligent enough to form their own
> opinions as to whether they want to allow OD function or not. If they
> decide to cancel OD, it is their choice and, as I had stated. if we
> are to make an "error", our error should save us money... not cost us
> money.
>
> Remember, in this venue, the past is not so distant and decent advice
> for one reader is terrible advice for another.
>


Well, I have plenty of experience with that as I work in a suburban venue
with a lot of 45 mph driving, about 1/3 mile between probable stops...
since my trans shifts pretty soft into OD anyway, i make sure to not use
OD.

Newer cars, fine... or if you're gonna drive it till it's three years
old, fine... but older cars that you're making a hobby of seeing how
long you can keep em on the road? Dont use OD when you dont need it.

--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
 
G

·
Discussion Starter · #7 ·
"Jim Warman" <[email protected]> wrote in message
news:[email protected]
>I don't believe I was making any waters muddy.... This NG encomapsses folks
>from all walks of life... including thse that are driving old
>technology.... not because they want to but because that's what they can
>afford.
>
> Additionally, I see no debate.... early overdrive transmissions had
> concerns with the overdrive function. Since torque is reduced through the
> use of overdrive, these components were often constructed of lighter
> material or less substantial amounts of materials.[if you have ever had
> one of these apart, you would know this is not true] Hunting between
> direct and overdrive has killed many A4LDs and AOTs.[I have never seen
> this]
>
> Your advice would lead those with these older units to believe that OD is
> OK in urban use,[according to the owners guides delivered with these
> vehicles it is] quite possibly causing them financial burdens they can ill
> afford.[why would anyone want to do that?]
>
> Are automatics designed to shift up and down??? Of course..... Does a
> certain amount of wear occur with each shift? Yes....[just as every
> component does] Will a "hunting" condition increase this wear? Yes... The
> transmission is chock full of sacrificial parts...[there it is, that
> conspiracy theory that car makers design things to fail] if there is an
> action that someone can take to increase the life span of these parts, it
> should be made known.[agreed, but it has nothing to do with overdrive]
>
> I have no idea where you are going with the "overdrive on the A4LD and AOD
> are an integral part of the trans"....[the parts are constructed exactly
> the same as the rest of the unit, meaning the shift to od is the same
> process as shifting to second or third] Of course this function is part
> and parcel of the transmission assembly..... How could it be otherwise?
> Even though this function is "integral" to the transmission, it does not
> follow that the function should either be used or allowed to operate at
> all times...[it was designed to function at all times] especially when we
> deal with older technology.
>
> Rather than offer a blanket "fugedaboudit" statement, these people deserve
> to know that there have been historical concerns with OD function in urban
> use.[urban legend] They are intelligent enough to form their own opinions
> as to whether they want to allow OD function or not. If they decide to
> cancel OD, it is their choice[yes, but let them form that opinion based on
> fact, not some ranting about how car makers design cars based on
> "sacrificial parts"] and, as I had stated. if we are to make an "error",
> our error should save us money... not cost us money.
>
> Now... getting back to your statement about the calibration of the engine
> controls..... On both the A4LD and the AOT the only "engine control" I can
> think of involved torque coverter lock. Overdrive function depended
> largely on either a vacuum modulator (for engine load sense) or a throttle
> valve cable (again for engine load sense). Where, in Gods name, does PCM
> calibration enter the picture?[as I said, ENGINE control, not TRANS; at
> the time the overdrives were released, the engines were not calibrated to
> run smoothly at high load, low rpm, causing conditions like bucking,
> pinging, trailer hitching, and the like. This is where the advice to
> cancel overdrive in city driving came from- unless you were running down
> the road at highway speeds the use of overdrive would cause driveability
> concerns. And, yes, shift hunting generated some concerns(but not harm)
> as well.]
>
> Remember, in this venue, the past is not so distant and decent advice for
> one reader is terrible advice for another.[well, I see...so if this venue
> is about giving advice based on hysteria and not fact, then I am in the
> wrong-but on the other hand, I don't recall that you were the one asking
> the question in the first place.]


To the original poster, if you are still following this and I don't blame
you if you aren't- the statement I made about fuel economy I still stand on-
as far as the use of overdrive is concerned, please use your own judgement.
My statement was unnecessary because you did not ask that question, and I
regret the argument that ensued.
I wish you well.
>
>
>
 
G

·
Discussion Starter · #8 ·
When you owed a car that had a three speed tranny did you move the selector
down so it would not shift back and forth at a particular speed, as well?
;)

mike hunt



"Backyard Mechanic" <[email protected]> wrote in message
news:[email protected]
>>

> Newer cars, fine... or if you're gonna drive it till it's three years
> old, fine... but older cars that you're making a hobby of seeing how
> long you can keep em on the road? Dont use OD when you dont need it.
>
> --
> Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
> you pay..DEAL with it!
 
G

·
Discussion Starter · #9 ·
When I owned a car with a 3 speed auto, it didn't hunt between it's
non-existant overdrive and direct and it didn't have lighter overdrive
parts. So... what is your point? You are only proving that apples have a
different taste than oranges.... not to mention a complete lack of knowledge
regarding the internals of a transmission. I suggest that you step up to the
plate and offer your views along with the reasons.....


"Mike Hunter" <[email protected]> wrote in message
news:[email protected]
> When you owed a car that had a three speed tranny did you move the
> selector down so it would not shift back and forth at a particular speed,
> as well? ;)
>
> mike hunt
>
>
>
> "Backyard Mechanic" <[email protected]> wrote in message
> news:[email protected]
>>>

>> Newer cars, fine... or if you're gonna drive it till it's three years
>> old, fine... but older cars that you're making a hobby of seeing how
>> long you can keep em on the road? Dont use OD when you dont need it.
>>
>> --
>> Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
>> you pay..DEAL with it!

>
>
 
G

·
Discussion Starter · #10 ·
"Ted" <[email protected]> wrote in message
news:[email protected]
>
>> To the original poster, if you are still following this and I don't blame

> you if you aren't- the statement I made about fuel economy I still stand
> on- as far as the use of overdrive is concerned, please use your own
> judgement. My statement was unnecessary because you did not ask that
> question, and I regret the argument that ensued.
> I wish you well.
>>
>>
>> Yeh, I'm still following the thread. Think I got what I wanted to know.
>> Thanks all for your comments, interesting reading :)



--
Paul O.
[email protected]
 
G

·
Discussion Starter · #11 ·
"Mike Hunter" <[email protected]> wrote:

> When you owed a car that had a three speed tranny did you move the
> selector down so it would not shift back and forth at a particular
> speed, as well? ;)
>
> mike hunt
>
>


:p

Dont be a dolt, MIKE... Tbird 3.8... it shifts into OD at 43 mph.. highest
practical speed about 45!!! And expect to drive at that speed about 15
seconds at most before slowing.

And Yes! When I had a Probe MT, I drove the same streets above in 4th..
wouldnt you?
When I had a Big Block FOUR SPEED manual I drove city 25 -35 mph zones in
3rd... didnt you?

--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
 
G

·
Discussion Starter · #12 ·
Ted wrote:
> No, very little difference at all; overdrive will increase gas mileage, but
> the effects will be the greatest at highway speeds. Think lower engine
> rpm=best economy. By the way, there is nothing to gain by cancelling
> overdrive operation in town, this is why it is enabled by default with every
> key cycle.


Actually I would guess the reason its back on after every key cycle is
so people won't drive down the hwy in 3rd. As for mileage it would
depend on your situation but it could lower your mpg if it lugs around
in OD. It is a fact with any automatic (without the torque converter
locked) it will get VERY hot going up a hill in overdrive, compared to
3rd(the converter is more likely to lock in 3rd too). If you don't
believe me install a trans temp gauge, then shortly after you will be
installing a cooler and downshifting to 3rd when going up hills :) I
personally don't put it in 3rd around town but most of the surface
streets around here you hit 45 or 50 easy, there are no hills, and I
also drive my cars easy. If I am pulling a trailer I will always put in
in 3rd unless going down a flat stretch of hwy with the converter
locked. It is absolutly amazing how fast the trans fluid can get to 300
+ climbing a hill in OD.
 
G

·
Discussion Starter · #13 ·
But it did hunt between second an third at a specific speed. I am merely
trying to understand the reasoning behind locking out OD when the fact is
whether the selector is in D or OD the tranny will not engage the OD gear
until a specific speed is reached, generally around 45 MPH What is the
point of moving the selector to D, at speeds below that speed, when 'city'
driving is less than 45? Manufactures suggest using D when towing or on
steep down grades to hold speed, or upgrades it the tranny is hunting,
generally

mike hunt



"Jim Warman" <[email protected]> wrote in message
news:[email protected]
> When I owned a car with a 3 speed auto, it didn't hunt between it's
> non-existant overdrive and direct and it didn't have lighter overdrive
> parts. So... what is your point? You are only proving that apples have a
> different taste than oranges.... not to mention a complete lack of
> knowledge regarding the internals of a transmission. I suggest that you
> step up to the plate and offer your views along with the reasons.....
>
>
> "Mike Hunter" <[email protected]> wrote in message
> news:[email protected]
>> When you owed a car that had a three speed tranny did you move the
>> selector down so it would not shift back and forth at a particular speed,
>> as well? ;)
>>
>> mike hunt
>>
 
G

·
Discussion Starter · #14 ·
Besides that info, I had an '84 CV wagon (land yacht) that in the owner's
manual stated that to avoid premature failure of the transmission to not
place the selector in Overdrive when driving consistently under 35mph or in
the city.


As usual, the best way to learn these things is by reading the manual....

"Backyard Mechanic" <[email protected]> wrote in message
news:[email protected]
> "Jim Warman" <[email protected]> wrote:
>
>
>> Your advice would lead those with these older units to believe that OD
>> is OK in urban use, quite possibly causing them financial burdens they
>> can ill afford.
>>
>> Are automatics designed to shift up and down??? Of course..... Does a
>> certain amount of wear occur with each shift? Yes.... Will a "hunting"
>> condition increase this wear? Yes... The transmission is chock full of
>> sacrificial parts... if there is an action that someone can take to
>> increase the life span of these parts, it should be made known.
>>
>>
>> Rather than offer a blanket "fugedaboudit" statement, these people
>> deserve to know that there have been historical concerns with OD
>> function in urban use. They are intelligent enough to form their own
>> opinions as to whether they want to allow OD function or not. If they
>> decide to cancel OD, it is their choice and, as I had stated. if we
>> are to make an "error", our error should save us money... not cost us
>> money.
>>
>> Remember, in this venue, the past is not so distant and decent advice
>> for one reader is terrible advice for another.
>>

>
> Well, I have plenty of experience with that as I work in a suburban venue
> with a lot of 45 mph driving, about 1/3 mile between probable stops...
> since my trans shifts pretty soft into OD anyway, i make sure to not use
> OD.
>
> Newer cars, fine... or if you're gonna drive it till it's three years
> old, fine... but older cars that you're making a hobby of seeing how
> long you can keep em on the road? Dont use OD when you dont need it.
>
> --
> Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
> you pay..DEAL with it!
 
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