Step by step guide on how to replace an automatic transmission. This article
pertains to most vehicles.
Tools and Supplies Needed
- Hydraulic jack
- High quality jack stands
- Transmission jack
- Wrench set (w/line wrenches)
- Socket set with various extensions
- Screwdriver Set
- Fluid catch pan
- Shop towels
- Replacement Transmission
- Fluid funnel
- Protective gloves and eyewear
Before beginning start with the car on level ground with the emergency brake
on and the engine off. Always lift the car by the manufactures recommended instructions
and secure the car with jack stands. Be sure to have plenty of clearance to work
under the vehicle.
- Begin by disconnecting the battery cable from the negative side
of the battery.
- Once completed, remove the vehicle’s driveshaft. On the rear
of the drive shaft is a universal joint. It is held to the differential by u-bolts.
Remove the u-bolts and pushing forward on the driveshaft, slip the u-joint away
from the differential.
- Carefully, slide the front yoke from the transmission housing
and remove the driveshaft.
- Remove wiring harnesses, vacuum hoses, or other external items
that are attached to the transmission. It is good practice to mark the location
on everything you remove so you remember how to reconnect them when you reinstall.
Masking tape and a marker will make things easy.
- Now, remove the shifter linkage and kick down linkage from the
transmission. These parts are usually steel rods or cables. Again, mark everything.
If your vehicle is equipped with a speedometer cable, remove it too. Also, unbolt
the transmission cooling lines that run from the transmission to the radiator. (note:
The linkage is usually connected with nothing more than retaining clips). When removing
them, keep an eye on them. They have a tendency to fly off and get lost. As far
as the speedometer cable, some screw onto the transmission housing others are retained
with a screw and a hold down.
- Next, remove the starter motor. There are two or three bolts
that hold it in place. Remove the bolts and carefully move it to the side, or disconnect
the wiring the remove the starter. Be carful not to damage any of the wiring.
- Now place a transmission jack under the transmission and slightly
lift up on it to remove pressure from the transmission mount and cross member.
- The transmission is held in place by a cross member which holds
the transmission mount and is also bolted on the other end to the engine by the
transmission bell housing. With the transmission jack holding the weight of the
transmission, remove the mount and cross member.
- Next, the transmission bell housing and torque converter bolts
need removed. For this, you will need a ratchet and most likely extensions to reach
the bolts on the bell housing. Some top bolts are easier to reach from the engine
compartment with a wrench. Remove all but one bell housing bolt.
- You will need a box end wrench or sockets to remove the torque
converter bolts. First, remove the inspection plate that is located at the bottom
of the transmission’s bell housing. With a flashlight, look up inside the inspection
plate to locate the bolts mounting the torque converter to the flexplate. Use a
breaker bar and socket, rotate the engine at the harmonic balancer to access and
remove the bolts (3 or 4 bolts). The torque converter should be free of the flexplate.
- Next, remove the last bell housing bolt. Once the last bolt
is removed use a leverage bar to "pop" the transmission loose from the engine block.
Lower the transmission slowly while slowly rolling it toward the rear of the car
and lower the transmission out from under the vehicle. Most manufacturers use locating
pins to correctly position the transmission to the engine. The transmission will
need to be slid back slightly before it detaches from the engine. Also, hold the
torque converter in place so it doesn’t fall forward and out of the transmission.
- After reinstalling the replacement transmission pour about five
quarts of fluid into the dipstick tub using a funnel. Then start the car and allow
to idle. Finish filling the transmission with fluid until full. Recheck fluid level
after several miles of driving.
Removing a transmission is not as difficult as it sounds. Most shops charge huge
amounts of labor time to remove and replace the unit. By removing it yourself, you
can save hundreds of dollars. A transmission can fail in many ways but some of the
most popular malfunctions include clutch slippage, internal breakage and fluid leaks.
While some repairs can be done with the transmission in the car for major repairs
the transmission must be removed. When replacing an automatic transmission consider
changing the transmission fluid cooler as well. This cooler is located inside the
radiator and it is likely the radiator will need to be replaced.
The fluid cooler can trap metal debris from the previous failed transmission.
This can cause premature failure of the replacement transmission. Transmissions
are heavy and a little awkward. A transmission jack should be used to hold the transmission’s
weight and help you slowly remove it from the vehicle. Often times people will use
a regular hydraulic jack to lower a transmission. However, the transmission can
slip off the jack and cause damage to the transmission or produce an injury.
- Inspect under the car after the new transmission has been installed and
inspect for fluid leaks.
- Listen for strange noises and report to manufacturer or builder.
Article first published 2009-07-28 (Updated 2015-04-25)