700r4 Torque Converter Question
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
700r4 Torque Converter Question
What directly controls the lockup clutches in the torque converter.
We know there is an electric circuit. But is the clutch manipulated by fluid pressure? Or controlled by an electric clutch?
Thanks JRC
We know there is an electric circuit. But is the clutch manipulated by fluid pressure? Or controlled by an electric clutch?
Thanks JRC
Race Director
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From: moraga ca
The lockup clutches are kept apart by tranny fluid in the converter. When 12 volts are supplied to the lockup solenoid in the tranny, fluid is exhausted from the torque converter (through the opening in the input shaft) allowing the clutch faces to contact.
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Ahhhhhh. SO if the solenoid is "soft" and not closing off the port fully when oil pressure increases, the TC clutch can release.(?)
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
What is happening as I roll in throttle lightly, lets say 55-60 mph, the torque converter unlocks. Enough throttle to maintain speed over a slight rise in the road. In the past this was not a problem and the TC stayed locked.
Instructor
Joined: Nov 2011
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the thottle position sensor could be bad also it will cause the converter to lock and unlock intermittanly there also a valve in the pump that applies the lock up when the soleniod is activated but most likely a tps aslo chect engine coolent temp sensor
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Thread Starter
Team Owner
Joined: Sep 2003
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Checking the TPS right now
383vett - New converter from PDQ (Sacramento)
...TPS was at .48 adjusted to .54. followed the voltage with an analog gauge.
Voltage was linear with no bumps or voids.
All works well when cold. Car pulls hard and shifts are crisp.
Everything goes to he11 once the temp is up.
I'm out cruising at 55mph, trans in forth (OD) TC locked (I think)
Little by little the tach starts to rise and speed slowly starts to drop.
I even got the UpShift to lite!
Got a lot of troubleshooting ahead.
Might be a TC, Pump or valve body...
Too much fun!
383vett - New converter from PDQ (Sacramento)
...TPS was at .48 adjusted to .54. followed the voltage with an analog gauge.
Voltage was linear with no bumps or voids.
All works well when cold. Car pulls hard and shifts are crisp.
Everything goes to he11 once the temp is up.
I'm out cruising at 55mph, trans in forth (OD) TC locked (I think)
Little by little the tach starts to rise and speed slowly starts to drop.
I even got the UpShift to lite!
Got a lot of troubleshooting ahead.
Might be a TC, Pump or valve body...
Too much fun!
Last edited by JrRifleCoach; Jun 8, 2012 at 01:43 AM.
Race Director
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
Checking the TPS right now
383vett - New converter from PDQ (Sacramento)
...TPS was at .48 adjusted to .54. followed the voltage with an analog gauge.
Voltage was linear with no bumps or voids.
All works well when cold. Car pulls hard and shifts are crisp.
Everything goes to he11 once the temp is up.
I'm out cruising at 55mph, trans in forth (OD) TC locked (I think)
Little by little the tach starts to rise and speed slowly starts to drop.
I even got the UpShift to lite!
Got a lot of troubleshooting ahead.
Might be a TC, Pump or valve body...
Too much fun!
383vett - New converter from PDQ (Sacramento)
...TPS was at .48 adjusted to .54. followed the voltage with an analog gauge.
Voltage was linear with no bumps or voids.
All works well when cold. Car pulls hard and shifts are crisp.
Everything goes to he11 once the temp is up.
I'm out cruising at 55mph, trans in forth (OD) TC locked (I think)
Little by little the tach starts to rise and speed slowly starts to drop.
I even got the UpShift to lite!
Got a lot of troubleshooting ahead.
Might be a TC, Pump or valve body...
Too much fun!
Thread Starter
Team Owner
Joined: Sep 2003
Posts: 20,170
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Therein lies one of the problems.
TC locks OK when cold. Hot, the lock is "soft" or non existent.
I've watched the signal from DataMaster.
TC locks OK when cold. Hot, the lock is "soft" or non existent.
I've watched the signal from DataMaster.
Race Director
Joined: Apr 2002
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From: Anaheim CA
The pump pressure in the trans tends to drop as the fluid warms up and thins out.
You can raise the pump pressure with a kit. You can install it by just dropping the pan. Higher pump pressure will give your TC a better grip and help the rest of the friction surfaces in the trans live longer. Slippage equals death in these transmissions.
...And adjust your TV cable. It directly affects pressures in your trans.
You can raise the pump pressure with a kit. You can install it by just dropping the pan. Higher pump pressure will give your TC a better grip and help the rest of the friction surfaces in the trans live longer. Slippage equals death in these transmissions.
...And adjust your TV cable. It directly affects pressures in your trans.
Thread Starter
Team Owner
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Will be hooking up a GM trans press gauge tool to record main, 2nd & 3rd gear pressures.
BTW This is a freshly overhauled trans. Gonna have to come out again....
BTW This is a freshly overhauled trans. Gonna have to come out again....
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
If you drive around with the trans pressure gauge hooked up, make sure it doesn't get close to the exhaust system.
I had the gauge tied up pretty well so it wasn't moving around. The hose was touching the shield on the exhaust manifold but I figured that was OK. I was wrong. When the hose burst and sprayed trans fluid all over the place it caught on fire. It was pretty entertaining to watch the flames coming out from under the car as I was going down the road. Good thing I carry a fire extinguisher...
I had the gauge tied up pretty well so it wasn't moving around. The hose was touching the shield on the exhaust manifold but I figured that was OK. I was wrong. When the hose burst and sprayed trans fluid all over the place it caught on fire. It was pretty entertaining to watch the flames coming out from under the car as I was going down the road. Good thing I carry a fire extinguisher...
Thread Starter
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Price - already have the Sonnax big servos installed. This trans pulls hard when cold. It falls apart when op temp reached.
Cliff - advise taken.
Cliff - advise taken.
Burning Brakes
Joined: Aug 2003
Posts: 944
Likes: 0
From: Mesa Az
The pump pressure in the trans tends to drop as the fluid warms up and thins out.
You can raise the pump pressure with a kit. You can install it by just dropping the pan. Higher pump pressure will give your TC a better grip and help the rest of the friction surfaces in the trans live longer. Slippage equals death in these transmissions.
...And adjust your TV cable. It directly affects pressures in your trans.
You can raise the pump pressure with a kit. You can install it by just dropping the pan. Higher pump pressure will give your TC a better grip and help the rest of the friction surfaces in the trans live longer. Slippage equals death in these transmissions.
...And adjust your TV cable. It directly affects pressures in your trans.
Burning Brakes
Joined: Aug 2003
Posts: 944
Likes: 0
From: Mesa Az
would that be the transmission slipping or the torque converter disengaging... ?