- Location
- Foresthill, CA
I've always been curious as to the interchangeability of Jeep AW4 parts and aisin A-340 parts. As it turns out, they have alot in common, including the ability to swap tailhousings and output shafts. In fact, it would be very easy to use a Toyota 7MGTE motor, with an A340 auto, and then hook it to an NP231 or 300, or Atlas, just by using an AW4 tailhousing and output shaft. The thing that has me interested right now is hooking an A340 to an 80 series T-case, which would allow me to use the 7MGTE in my buggy, which has 80 series axles.
Enough blathering, on to the article from TransTec.
CRASH
The Evolution of the A340
Don Cottrell, TransTec Product Technician
Aisin Warner has produced the
A340 series transmission for
over a decade. It was first introduced
in 1985 for the Toyota Pickup and 4-
Runner line. In a two-wheel drive
version, its designation is A340E. Its
four-wheel drive version used from
1985-94 is designated A340H. The
“H” suffix led some builders to think it
stood for hydraulically-shifted transmission,
but what it really represents is
that it is coupled to a hydraulic transfer
case, instead of a mechanical one. The
transmission is electronically shifted in
both the A340E and the A340H.
Pleased with the durability of the
Aisin Warner A340E transmission,
Toyota added it to the Supra line in
1986. Aisin Warner felt so successful
with the performance of their transmission
that they began to market it to
other automakers.
The first auto manufacturer in the
states that started fitting the A340
series into their own line of trucks and
sport utilities was Chrysler Corporation.
The A340 series of transmissions
produced for Chrysler was designated
AW-4. This unit was used in all 4.0
litre, two-wheel drive and four-wheel
drive Jeep Wagoneers, Cherokees,
Grand Cherokees and Comanches. The
only exception was the 1994-98 Grand
Cherokee, which used the A500.
Chrysler took a different approach
to their four-wheel drives. They went
with a mechanical transfer case instead
of a hydraulic unit like the 1985-94
Toyota four-wheel drives. This was
usually a less costly repair, because
you could separate the transfer case
from the transmission just by unbolting
it from the transmission’s adapter
housing. In Toyota four-wheel drives,
on the other hand, you had to disassemble
the transfer case to get to the
bolts that held it to the transmission. To
do the early Toyotas right, you have to
rebuild the transfer case as well as the
transmission, and add the cost of doing
this to the job.
Isuzu used the A340H in its Trooper
line since the Trooper’s inception in
1988, up through 1991 in vehicles with
a 2.6L inline 4-cylinder, and a 2.8L V6.
Isuzu, like Toyota, also had the
hydraulic transfer case that was capable
of true “shift on the fly.”
In 1990, Aisin Warner started
producing the sister to the A340E,
designated the A341E. Lexus was the
first automaker to use the A341E. It
debuted in the LS400 line in 1990, the
SC400 in 1992, the GS300 in 1993, and
the SC300 in 1998. Toyota used the
A341E in the 1993-98 Supra, paired
with the 3.0L twin cam turbo engine.
Volvo also used this unit with a
designation of AW 40 in its 960 series
from 1993-97, and its 90 series for
1998-up.
The A341E was only produced in a
two-wheel drive version. It is basically
a beefier A340E, with a shorter output
shaft and extension housing, and a bolton
flange yoke. These external characteristics
readily distinguish the A341E
from its sister, the A340E. Internally,
you will see numerous changes. There
is a different pump, clutch pack
changes, an added shift (line pressure)
control solenoid, and changes to the
valve body for line pressure modulation.
You will also notice that the lock-up
control solenoid went from an on/off
type to a pressure modulation type.
The 1993-98 Supra 3.0L turbo and
the 1998-up Lexus SC300 went one step
further on their A341E, and added a
throttle control solenoid that controls
hydraulic pressure to the back chamber
of the accumulators. This helps control
shift feel.
In 1995, Toyota decided to do away
with their hydraulic transfer case and go
with a conventional mechanical transfer
case. This was a welcome change to
most rebuilders and owners, since you
no longer had to disassemble the
transfer case and build it along with the
transmission. The new designation for
the four-wheel drive units with a
separate transfer case is “A340F.” This
unit was used in all of their four-wheel
drive vehicles from 1995-up, except for
the Landcruiser. Mitsubishi also used
the A340F in their 1995-98 Montero.
Another event that took place in
1995 was the addition of another version
of the A340 series. This new version
was designated A343F, and it was only
produced in a four-wheel drive version.
The only applications this was used in
were the high line four-wheel drives like
the Lexus LX450 and LX470, as well as
the 1995-up Landcruiser.
The 1995-97 A343F is basically an
A341E internally, with the exception of
the output shaft and some clutch pack
changes. It also uses the A340E type
valve body instead of the shift control
solenoid valve body like in the A341E.
In 1998, the A343F underwent a face lift
A
4
and had the shift control (line pressure)
solenoid added to the hydraulics, as
well as a throttle control solenoid.
All of the A340 series of transmissions
are generally very reliable. But
close attention is needed when doing a
rebuild. The valve body has had many
changes from model to model, and you
need to pay close attention to all the
check ball locations since they’ve been
moved around a lot.
One area of concern is that the
throttle position sensor on the Jeep
applications goes bad quite often,
causing what is generally described as a
neutralizing condition while at cruise.
Another weak point is the famous
“Toyota clogged shift solenoid syndrome,”
as well as problems with the
speed sensors going bad.
Several of the tech services have
good technical manuals available for
these units, and it is highly advised to
have them on hand when tackling one
of these for a rebuild.
If you think all this is confusing
enough, think again, because the latest
trend is not towards simplicity. The
new generation of 5-speed is here, and
there are two different versions out
already. The first is the A350E, and the
second is the A650E. But that’s another
story……..
Enough blathering, on to the article from TransTec.
CRASH
The Evolution of the A340
Don Cottrell, TransTec Product Technician
Aisin Warner has produced the
A340 series transmission for
over a decade. It was first introduced
in 1985 for the Toyota Pickup and 4-
Runner line. In a two-wheel drive
version, its designation is A340E. Its
four-wheel drive version used from
1985-94 is designated A340H. The
“H” suffix led some builders to think it
stood for hydraulically-shifted transmission,
but what it really represents is
that it is coupled to a hydraulic transfer
case, instead of a mechanical one. The
transmission is electronically shifted in
both the A340E and the A340H.
Pleased with the durability of the
Aisin Warner A340E transmission,
Toyota added it to the Supra line in
1986. Aisin Warner felt so successful
with the performance of their transmission
that they began to market it to
other automakers.
The first auto manufacturer in the
states that started fitting the A340
series into their own line of trucks and
sport utilities was Chrysler Corporation.
The A340 series of transmissions
produced for Chrysler was designated
AW-4. This unit was used in all 4.0
litre, two-wheel drive and four-wheel
drive Jeep Wagoneers, Cherokees,
Grand Cherokees and Comanches. The
only exception was the 1994-98 Grand
Cherokee, which used the A500.
Chrysler took a different approach
to their four-wheel drives. They went
with a mechanical transfer case instead
of a hydraulic unit like the 1985-94
Toyota four-wheel drives. This was
usually a less costly repair, because
you could separate the transfer case
from the transmission just by unbolting
it from the transmission’s adapter
housing. In Toyota four-wheel drives,
on the other hand, you had to disassemble
the transfer case to get to the
bolts that held it to the transmission. To
do the early Toyotas right, you have to
rebuild the transfer case as well as the
transmission, and add the cost of doing
this to the job.
Isuzu used the A340H in its Trooper
line since the Trooper’s inception in
1988, up through 1991 in vehicles with
a 2.6L inline 4-cylinder, and a 2.8L V6.
Isuzu, like Toyota, also had the
hydraulic transfer case that was capable
of true “shift on the fly.”
In 1990, Aisin Warner started
producing the sister to the A340E,
designated the A341E. Lexus was the
first automaker to use the A341E. It
debuted in the LS400 line in 1990, the
SC400 in 1992, the GS300 in 1993, and
the SC300 in 1998. Toyota used the
A341E in the 1993-98 Supra, paired
with the 3.0L twin cam turbo engine.
Volvo also used this unit with a
designation of AW 40 in its 960 series
from 1993-97, and its 90 series for
1998-up.
The A341E was only produced in a
two-wheel drive version. It is basically
a beefier A340E, with a shorter output
shaft and extension housing, and a bolton
flange yoke. These external characteristics
readily distinguish the A341E
from its sister, the A340E. Internally,
you will see numerous changes. There
is a different pump, clutch pack
changes, an added shift (line pressure)
control solenoid, and changes to the
valve body for line pressure modulation.
You will also notice that the lock-up
control solenoid went from an on/off
type to a pressure modulation type.
The 1993-98 Supra 3.0L turbo and
the 1998-up Lexus SC300 went one step
further on their A341E, and added a
throttle control solenoid that controls
hydraulic pressure to the back chamber
of the accumulators. This helps control
shift feel.
In 1995, Toyota decided to do away
with their hydraulic transfer case and go
with a conventional mechanical transfer
case. This was a welcome change to
most rebuilders and owners, since you
no longer had to disassemble the
transfer case and build it along with the
transmission. The new designation for
the four-wheel drive units with a
separate transfer case is “A340F.” This
unit was used in all of their four-wheel
drive vehicles from 1995-up, except for
the Landcruiser. Mitsubishi also used
the A340F in their 1995-98 Montero.
Another event that took place in
1995 was the addition of another version
of the A340 series. This new version
was designated A343F, and it was only
produced in a four-wheel drive version.
The only applications this was used in
were the high line four-wheel drives like
the Lexus LX450 and LX470, as well as
the 1995-up Landcruiser.
The 1995-97 A343F is basically an
A341E internally, with the exception of
the output shaft and some clutch pack
changes. It also uses the A340E type
valve body instead of the shift control
solenoid valve body like in the A341E.
In 1998, the A343F underwent a face lift
A
4
and had the shift control (line pressure)
solenoid added to the hydraulics, as
well as a throttle control solenoid.
All of the A340 series of transmissions
are generally very reliable. But
close attention is needed when doing a
rebuild. The valve body has had many
changes from model to model, and you
need to pay close attention to all the
check ball locations since they’ve been
moved around a lot.
One area of concern is that the
throttle position sensor on the Jeep
applications goes bad quite often,
causing what is generally described as a
neutralizing condition while at cruise.
Another weak point is the famous
“Toyota clogged shift solenoid syndrome,”
as well as problems with the
speed sensors going bad.
Several of the tech services have
good technical manuals available for
these units, and it is highly advised to
have them on hand when tackling one
of these for a rebuild.
If you think all this is confusing
enough, think again, because the latest
trend is not towards simplicity. The
new generation of 5-speed is here, and
there are two different versions out
already. The first is the A350E, and the
second is the A650E. But that’s another
story……..