81 Tranny Wiring.

1954 Views 13 Replies 4 Participants Last post by skd81shark, Apr 9, 2007

skd81shark

Discussion Starter · Mar 24, 2007

Okay here's the deal.

My 81 originally had an electronic lockup THM350c. (I know, because it is sitting on the floor of the garage right now). Lol...one local tranny shop said there was no such thing as an electronic lockup THM350C he was upset when I showed it to him.):smack

I am installing a THM700R4. Got the Croos member and kit, along with shifter mod (Thanks Bowtie Overdrives and Shiftworks!)

Now, in this little adventure I discovered something odd.

The 350c has a two prong wiring receptacle for the harness pigtail.
The 700R4 has a 3 prong one. (Identical, same shape/size)

The car has a 4 prong pigtail. Said 4 prong pigtail allowed THM350 to shift just fine and dandy.

Anybody know if 81's were prewired for a 700R4? Maybe a production delay kept them out, or maybe my car is a late 81, so has 82 crossover parts?:WTF

Just wondering if said harness will actuate and release the lockup in the 700....would save a buttload of time, and eliminate extra wires.

Anybody done this before? The parts in the Bowtie kit (I bought the brake pedal switch kit) look identical! The plug, the Switch (I just bought a new Brake light switch from GM about 5 months ago. EXACT same switch, just in GM white, instead of Bowtie Overdrives Black. Same config, same # of prongs, etc....then there is that harness pigtail......any clues?:huh:

Steve

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skd81shark

Discussion Starter · #4 · Mar 25, 2007

Cool info! Thanks!

Well, Trans is in...
Did your stock TV cable work with the additional length of the 700R4?

They are pulling apart the rear end today..for complete rebuild. Driveline get picked up tomorrow.

On an interesting note, I noticed you had problems with the Shiftworks shifter conversion. Did you get these straightened out?

How does she run now?
Also.. need to figure out the Speedo gear thing...my Trans did not come with the gear that drives the Speedo/odo. What did you use? I need the gear and the bracket thingy to allow the cable to mount, also, did your stock speedo cable work?
What was the deal about the wire on the ECM? Do I need to worry about that?
Steve

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skd81shark

Discussion Starter · #6 · Mar 25, 2007

Thanks for the advice!

Anything else I should watch for? the shakedown is about 3 days away. As soon as the rear gets buttoned up, and the top end of the motor is buttoned up, its RUMBLE TIME! whoohooo!

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skd81shark

Discussion Starter · #8 · Mar 26, 2007

Why no first gear?:WTF

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skd81shark

Discussion Starter · #11 · Mar 27, 2007

Got it. Not too worried about it selecting first, (though would be nice) think that could be fixed later. As long as it shifts and doesn't chew itself up, and unlocks when it is supposed to, that is the major checkpoint.

Got the driveline back today...all balanced and pretty with new U joints, Rear end drops tomorry. They should have that done in one day. Praying for the speedo thingy, and the gear. If they have it locally.......I will be................

ALMOST THERE! WHOOOOOOOHOOOOOOOOO!!!!!!!!!!!!!!!!!

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skd81shark

Discussion Starter · #13 · Mar 30, 2007

Found the Speedo thingies. (The nubbis looking speedo housing, the gear, o ring and the clamp)

Finally, the mechanic has the %@$% rear end out and apart, found out the rear end was about ready to explode, the clutch packs were working out, one of the keepers was disintigrated, and the others were working their way out.

Good thing I bought all that junk already. Everything is cleaned and he will have it reassembled tomorrow (We are now 5 days late getting back to body shop...NOT Happy!!)

Then reinstall into car, do TV, Do Shifter, Button up engine, THEN we can figure out if she works or not. JHC, I am going nuts!

:thud:
Steve

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skd81shark

Discussion Starter · #14 · Apr 9, 2007

FINALLY
Mechanic has Rear end in Car...should fire tomorrow...JHC what a nightmare. Had to replace ignition switch. If I ever meet the stupid designer who thought it was a really great idea to put the ignition switch where it is, and make it nearly impossible to get to....they get a free kick in the junk. Maybe two, depending how foul a mood I am in that day.

Update on the Tranny. The Shiftworks kit works Great! It selects all gears including first! Their carb plate, is not needed, use the TV cable from Bowtie OD, and plug it into the stock bracket, you need it for the throttle cable and the vaccuum diaphragm on the 81 anyway.

This has been a fun, though fustrating adventure....what started as a "freshen up the Engine" has turned into nearly a frome on resto. Only 6K overbudget! Lol.

Car should be painted in the next two weeks, saying of course I don't have another disgusting emergency. Lol. I think I need to kick my car's last owner in the cajones a few times as well. Poor vette was ABUSED!

Steve

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