Question about a 1981 Automatic Transmisson
05-20-2016, 05:22 PM
#1
TheCorvetteBen
Thread Starter
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!
05-20-2016, 08:32 PM
#3
Unless the owner swapped in some 4.10 gears you better have a trans shop check out the transmission. You should be turning about 1600-1800 at 60mph with factory gearing in 4th gear.
05-20-2016, 10:52 PM
#5
Racer
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!
05-21-2016, 01:42 AM
#6
TheCorvetteBen
Thread Starter
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!
05-21-2016, 06:32 AM
#7
Team Owner
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.
05-21-2016, 07:20 AM
#8
Drifting
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.
05-22-2016, 05:11 PM
#11
Racer
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.
05-23-2016, 03:37 PM
#12
I have that B&M switch and its expensive but works great. I have my lockup set at 60MPH. I also hid the controller by taking out the ashtray and fitting it in the "window". Looks cool and out of the way.
