Question about a 1981 Automatic Transmisson
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
Question about a 1981 Automatic Transmisson
I am considering a 1981 vette, but I am looking for opinions/options about the transmission. Here is the situation:
Like most 1981 corvettes, the computer controlled distributor and carb have been swapped out for non computer controlled units. As such, the computer has been disconnected. The owner of the car says that the lock up converter does not lock up, and at about 60 mph you are turning something like 3000 to 3500 rpm. I am assuming that the computer was what controlled this lock up converter.
I know that a regular 350 turbo trans would bolt right up and work just fine for this car. Is there anything I can wire in that can manually lock up the converter without the computer? like some kind of switch? I know 81s and 82s were the only ones with this kind of transmission, so it will be easier to find one that does not have any sort of electronics in it, but I thought I would ask here first. I just don't want to swap anything out if I don't have to!
Thanks!
Like most 1981 corvettes, the computer controlled distributor and carb have been swapped out for non computer controlled units. As such, the computer has been disconnected. The owner of the car says that the lock up converter does not lock up, and at about 60 mph you are turning something like 3000 to 3500 rpm. I am assuming that the computer was what controlled this lock up converter.
I know that a regular 350 turbo trans would bolt right up and work just fine for this car. Is there anything I can wire in that can manually lock up the converter without the computer? like some kind of switch? I know 81s and 82s were the only ones with this kind of transmission, so it will be easier to find one that does not have any sort of electronics in it, but I thought I would ask here first. I just don't want to swap anything out if I don't have to!
Thanks!
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Racer
Joined: Nov 2011
Posts: 319
Likes: 12
From: South Chase WI
Just put a switch in. Easy. The wires are easily accessible on the brake pedal, there is a switch there for the brake light and trans. It unlocks when you hit the brakes, opens the circuit. So wire a switch to give power to the circuit when you chose, via the switch, which will lock up the trans. Touching the brake pedal will unlock it, as it should. Only turn the switch "on" when on the highway so the engine does not lug from the trans going into lock up too fast. I did this on my 81 WITH the computer still functioning, much nicer to drive in town, when I hit the highway I engage the switch. Hope this helps!
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
Just put a switch in. Easy. The wires are easily accessible on the brake pedal, there is a switch there for the brake light and trans. It unlocks when you hit the brakes, opens the circuit. So wire a switch to give power to the circuit when you chose, via the switch, which will lock up the trans. Touching the brake pedal will unlock it, as it should. Only turn the switch "on" when on the highway so the engine does not lug from the trans going into lock up too fast. I did this on my 81 WITH the computer still functioning, much nicer to drive in town, when I hit the highway I engage the switch. Hope this helps!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
As mentioned above, if the car is turning over 3000 rpm at 60mph, then it has 3.56 or 3.73 gears in the back. Getting the L/U to work will only drop that about 10% to a bit less than 3K rpm....still a pain at 60mph (not even normal Interstate speed).
Unless you particularly want a drag car (an '81 Corvette 'drag car'?....I think that's an oxymoron), you'd best forget that one and move on. The only way to make that into a decent 'driver' car would be to swap out the rear end for 3.08/3.23/3.36 or install a 4-speed auto trans with L/U. Troublesome and costly, either way.
Unless you particularly want a drag car (an '81 Corvette 'drag car'?....I think that's an oxymoron), you'd best forget that one and move on. The only way to make that into a decent 'driver' car would be to swap out the rear end for 3.08/3.23/3.36 or install a 4-speed auto trans with L/U. Troublesome and costly, either way.
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
yes, you can install a pressure switch on 3rd gear.. problem is that it will engage way to soon at light throttle making engine lug at low speed in town.. the on/off switch in the cabin will prevent that and let you engage only on hiway.. AGAIN, please understand, your 3500 rpm is NOT because of the TCC not engaging.... your car came stock with a 2.87 rear gear.. @60mph, a 27 inch tire in 3rd gear, you would only be turning 2150 RPM....the gears have been changed.
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Le Mans Master
Joined: Dec 2007
Posts: 6,422
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From: McHenry Illinois
Racer
Joined: Nov 2011
Posts: 319
Likes: 12
From: South Chase WI
My switch is a tiny little toggle, mounted right below the emergency brake handle. Very convenient. To me it's like an OD switch on a newer car. Not a bother nor inconvenience at all. Highway use or long country roads only pretty much. Otherwise it is off.
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Joined: Jun 2001
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