81 auto transmission ?
Thread Starter
Burning Brakes
Joined: Apr 2005
Posts: 944
Likes: 5
From: danvers il
81 auto transmission ?
I have an auto tranny that has a lock up torque converter. I don't understand the purpose or need of this solenoid. This tranny works fine without the wiring for the solenoid. Do I need to have it wired up to make the tranny work better? can someone explain it to me.
thanks
thanks
Melting Slicks
Joined: May 2003
Posts: 2,078
Likes: 283
From: Dyersburg TN
a torque converter is designed to slip allowing the transmission to be in gear without stalling the engine. But since it slips you loose some power and the engine runs a little faster. When the converter locks, it is a direct drive like a stick shift and your engine RPM will drop around 300. This RPM drop will help the wear on the engine, boost milage and deliver full power to the wheels with no slipage. You don't have to have it, but if it can work, use it.
Melting Slicks
Joined: Mar 2007
Posts: 2,520
Likes: 11
From: Hinckley OH
a torque converter is designed to slip allowing the transmission to be in gear without stalling the engine. But since it slips you loose some power and the engine runs a little faster. When the converter locks, it is a direct drive like a stick shift and your engine RPM will drop around 300. This RPM drop will help the wear on the engine, boost milage and deliver full power to the wheels with no slipage. You don't have to have it, but if it can work, use it.
I would just add that it only locks in high gear.
Melting Slicks
Joined: May 2003
Posts: 2,078
Likes: 283
From: Dyersburg TN
factory switch
many owners disconnected it because the pressure switch in the trans was set for too low a pressure and the converter kept lock/unlocking at cruse speed. Most transmission shops have a switch that closes at higher pressure so it only engages at highway speed. The 81 passed control through the CCU but many bypass that and set it up like previous years. There are two wires on the TH350c that go to the solenoid and the before mentioned pressure switch inside the transmission. Give it 12 volts (that can be broken by stepping on brake) and a ground and it works.
good luck
good luck
Race Director
Joined: Oct 2000
Posts: 12,682
Likes: 3,135
From: Shamong, NJ
From the label attached to the drivers side door glass on every new automatic equipped 81.
"Purchaser Please Note" "This vehicle is equipped with a clutch-type torque converter automatic transmission designed to help improve fuel economy."
In 81 they were trying to do everything they could to milk another fraction of a mile per gallon out of all cars. The lock up torque converter was one of the solutions.
"Purchaser Please Note" "This vehicle is equipped with a clutch-type torque converter automatic transmission designed to help improve fuel economy."
In 81 they were trying to do everything they could to milk another fraction of a mile per gallon out of all cars. The lock up torque converter was one of the solutions.
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Instructor
Joined: Jun 2010
Posts: 130
Likes: 0
From: Summerville SC
Is there a diagram of the wiring for this in the '81 shop manual? Mine is disconnected as well. Just red and blue wires coming up from the tranny and terminated in the engine compartment. I have no idea where they should go.
Melting Slicks
Joined: May 2003
Posts: 2,078
Likes: 283
From: Dyersburg TN
if by terminate you disconnect, yes. Nothing comes out of the two wires if they are not connected to the car. The leads from the car will be a ground and 12v if you are not stepping on the brake (and assume the rest is working).
simple system, boost mileage a bit, lower engine RPM (noise) at highway speed. IMHO worth fix if converter is in working order.
simple system, boost mileage a bit, lower engine RPM (noise) at highway speed. IMHO worth fix if converter is in working order.
