1990 lock up auto trans
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,074
From: Lansing MI
The torque converter is a fluid coupler, so it slips a little bit. Said another way. one revolution of the crankshaft equals less than one revolution of the input shaft into the transmission. So the lockup clutch is a part of the converter that locks the internals of the converter so you get a 1 to 1 ratio.
Watch your tachometer. You will see rpms drop by about 150 when the converter locks up. The easiest way to witness this is get on the highway and cruise at 70 in overdrive, while watching the tach, just touch the brake pedal, not enough to slow down, just enough to turn the brake lights on. The converter will unlock, and you will see the tach jump up just slightly, when you let off the brake, the converter will lock up again.
Watch your tachometer. You will see rpms drop by about 150 when the converter locks up. The easiest way to witness this is get on the highway and cruise at 70 in overdrive, while watching the tach, just touch the brake pedal, not enough to slow down, just enough to turn the brake lights on. The converter will unlock, and you will see the tach jump up just slightly, when you let off the brake, the converter will lock up again.
Last edited by PatternDayTrader; Aug 25, 2018 at 09:34 PM.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
The torque converter is a fluid coupler, so it slips a little bit. Said another way. one revolution of the crankshaft equals less than one revolution of the input shaft into the transmission. So the lockup clutch is a part of the converter that locks the internals of the converter so you get a 1 to 1 ratio.
Watch your tachometer. You will see rpms drop by about 150 when the converter locks up. The easiest way to witness this is get on the highway and cruise at 70 in overdrive, while watching the tach, just touch the brake pedal, not enough to slow down, just enough to turn the brake lights on. The converter will unlock, and you will see the tach jump up just slightly, when you let off the brake, the converter will lock up again.
Watch your tachometer. You will see rpms drop by about 150 when the converter locks up. The easiest way to witness this is get on the highway and cruise at 70 in overdrive, while watching the tach, just touch the brake pedal, not enough to slow down, just enough to turn the brake lights on. The converter will unlock, and you will see the tach jump up just slightly, when you let off the brake, the converter will lock up again.
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
lightly pressing the brake while going uphill will release the torque converter lock and rpm will climb a little depending on load.
