Well - according to my FSM, for my 1989 - A-500, the transmission will shift
into overdrive with a below 70% throttle condition... above 70% and there is
no overdrive shift, or if you accelorate to above 70% throttle... it will drop
out of OD.
I think that it is a rather personal kind of thing LOL. Each truck is
different. Each driving habit is different. I have learned to drive with
over drive on and optomize its potential. I try to coast as much as possible,
and keep my engine RPM's around 1200-1400 when driving. I have learned to
acelorate accordingly witht he 70% OD ratio. Sure I would be accelorating
slower... but then again lately I am focused more on fuel economy than with
flooring it off the line at a light.
As for trans wear... I wouldn't be as concerned about it if I knew my
transmission fluid was being cooled properly.
Ken Allgood wrote:
> I'm gonna have to go out on a limb here and disagree with the responses
> here.
>
> 1 - OD off DOES make a difference under 40mph... the OD changes 2 main
> things that i'm aware of.. Your shift points at Part Throttle, and shift
> point for OD gear. Try this.. with your OD on, drive at 35 mph.. now, give
> it about 1/2 throttle, and it'll kick down and come alive pretty good.. with
> the OD off, you'll already be sitting at the higher revs and normally won't
> have to kick down.
>
> 2 - I normally turn it off for city driving. Here's the reason why - speed
> limit around here in town is 45mph, and I do a lot of stop and go, fluctuate
> from 30 to 50mph, etc, and I like to give it about 1/2 throttle... does a
> LOT of shifting with OD on (hint hint.. transmission wear!!!), with OD off,
> it doesn't do nearly the amount of shifting.. Especially around 45mph.. if
> i'm holding it at 45-50mph, I leave OD on.. but if I give it just a little
> gas, it downshift, speeds up, and then shifts back up... quite annoying and
> lots of wear on transmission
-- -----------------------------------"Hey Ray! Granpa done gone'n hit another light pole!"
Granpa - (Silver98) http://members.aol.com/silvereightynine/
1989 Reg Cab, V6, Auto, 8 footer, 4x2 1989 Reg Cab, V6, Auto, 8 footer, 4x4 w plow
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