5 speed automatic in my Legacy?

[S]

Hi All!

I have a new (well, new to _me_, anyway ;-) '96 Legacy L sedan with a
4spd automatic gearbox. This is the first automatic car I have owned
(or at least driven much) in many years, so maybe this is a dumb
question, but . . .

It would appear to have an extra gear, and I'm wondering if anyone can
shed a little light on this.

Here is the situation:
Interstate at ~70MPH on level ground, light pressure on the throttle,
and ~2500RPM on the tach. Mileage mode. Pull out to pass, give a
little push on the fun pedal, the engine comes up to ~3000RPM, and off
you go. If you seriously mash the pedal, it will _really_ downshift,
and the engine speed will go to ~4200RPM, which is consistent with
~70MPH in 3rd.

My question is: How does the tranny achieve the appearance of a 5th
gear/overdrive out of a 4spd gear train? Inquiring minds and all . . .

ByeBye! S.
Automatic Transmission Newbie

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

 

[Jeff]

Hi All!

I have a new (well, new to _me_, anyway ;-) '96 Legacy L sedan with a
4spd automatic gearbox. This is the first automatic car I have owned
(or at least driven much) in many years, so maybe this is a dumb
question, but . . .

It would appear to have an extra gear, and I'm wondering if anyone can
shed a little light on this.

Here is the situation:
Interstate at ~70MPH on level ground, light pressure on the throttle,
and ~2500RPM on the tach. Mileage mode. Pull out to pass, give a
little push on the fun pedal, the engine comes up to ~3000RPM, and off
you go. If you seriously mash the pedal, it will _really_ downshift,
and the engine speed will go to ~4200RPM, which is consistent with
~70MPH in 3rd.

My question is: How does the tranny achieve the appearance of a 5th
gear/overdrive out of a 4spd gear train? Inquiring minds and all . . .

ByeBye! S.
Automatic Transmission Newbie

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

I am willing to et that you have what is called a lock up torque converter.
This is a step the removes the hydraulic coupling in the torque converter
and goes to direct drive.

It gives the appearance of another gear but is not.

Hope this helps

 

[John]

I agree with Jeff, it is the lockup torque converter. The lockup is done in
4th gear when cruising but a little pressure on the gas will unlock the
converter and result in higher rpms. Mostly used as a gas saver.

 

[Bruce Hoult]

I am willing to et that you have what is called a lock up torque converter.
This is a step the removes the hydraulic coupling in the torque converter
and goes to direct drive.

No need to bet, Subarus of that vintage (such as my '95) do indeed have
lock-up torque converters.

It gives the appearance of another gear but is not.

Mechanically, of course, it is not actually another gear, but in every
way that counts it effectively is. You get lower RPM at cruise which
makes the car feel more relaxed and also improves fuel economy. Energy
is not being wasted in slip in the torque converter which gives an
additional improvement in fuel economy. And when locked up the car acts
just like a manual car in top gear (except that the top gear on
automatics is usually taller than the top gear on manuals) -- you get
direct and immediate response to small changes in accelerator setting,
including getting engine braking that you wouldn't normally get on an
automatic. And my '95 2.5l Legacy wagon will go up all but the steepest
hills on the open road here in NZ while still locked up in 5th, as long
as you don't have to slow down for other reasons (e.g. corners). The
fast you're going, the harder you ahve to press to unlock the torque
converter -- at 60 km/h (1500 rpm on mine) it takes only a very small
press, but at 120 kmh (3000 rpm) you have to press the pedal probably a
third to half way down. This is somethign I like very much about the
Subaru's automatic -- it knows that there's a torquey engine there and
it will let you make use of the torque almost like you can in a manual
car where many automatics will change down a few gears and rev the crap
out of the engine as soon as you hint at pressing the pedal.

And, as the original poster notes, the extra 500 rpm you get when you
press hard enough to unlock the torque converter will very often provide
all the extra power you need, and is very very similar in effect to
changing down from 5th to 4th in a manual car.

 

[MN]

Very interesting discussion. No matter how old one is,
or how knowledgeable, there is always so much new
stuff to learn.

Alt.autos.subaru is one hell of a newsgroup!
Thanks guys

MN

 

[S]

Hi All!

Very interesting discussion. No matter how old one is,
or how knowledgeable, there is always so much new
stuff to learn.

Alt.autos.subaru is one hell of a newsgroup!
Thanks guys

I'll second that!

Bruce, do you happen to know how the lock-up effect is achieved? Is it
inherent to the design of the impellers within the TC, or is there an
electrical signal to increase the pressure (or whatever) of the fluid
being delivered to the unit?

Whatever, it works great. Kudos to Subaru for a very drivable AT car!
I take back at least _some_ of the bad things I've said about
automatics over the years ;-)

Thanx for the insight, guys!

ByeBye! S.

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

 

[Tom Reingold]

Whatever, it works great. Kudos to Subaru for a very drivable AT car!
I take back at least _some_ of the bad things I've said about
automatics over the years ;-)

Thanx for the insight, guys!

Yeah, almost makes me wish I bought an automatic!

But I haven't owned one yet.

Tom

 

[Tcassette]

If you live in an area with seasonal cool to cold temperatures, be aware
that the lockup will not function until the engine is warmed up to a certain
temperature. In other words, you will not get that final drop down in
engine RPM at cruising speeds for a period directly proportional to how
cold it is. It's one reason the winter fuel mileage drops a bit.

 

[Bruce Hoult]

Bruce, do you happen to know how the lock-up effect is achieved? Is it
inherent to the design of the impellers within the TC, or is there an
electrical signal to increase the pressure (or whatever) of the fluid
being delivered to the unit?

No, not precisely. Just what I've learned from driving one for nearly
100,000 km One thing that is interesting .. it takes about seven
seconds for lock-up to happen after all the conditions are right for it.

I found some interesting web pages:

http://www.subaru-global.com/about/parts/07.html
http://www.bankspower.com/Tech_understandtorqueconver.cfm
http://www.leeric.lsu.edu/bgbb/7/ecep/auto/f/f.htm

Whatever, it works great. Kudos to Subaru for a very drivable AT car!
I take back at least _some_ of the bad things I've said about
automatics over the years ;-)

I agree. I hate automatics in general, but Subaru's is really quite
pleasant. I would imagine that they're all getting better but I've
driven cars owned by friends/family that are newer than mine and *hated*
the automatics -- especially the Nissan and Mitsubishi ones. Another
friend's Mazda Capella seemed quite good though, as was a brand new Ford
Territory that I was driving eight hours a day for a few weeks for work
recently (much much nicer than older Ford Falcon's I've driven).