About two years ago, I pulled the computer out of my 82. I had so many problems, that was without doubt where to start. I almost have the engine running where I want it...it took a lot of work, but it runs well now.

I've read that our trasmissions are dependant on the ECM. What do I need to do to my torque converter/transmission now that I don't have a computer onboard?

 

Install a vacuum operated TH350. The 700R4 has 2 **** solenoids that are electronically controlled, and won't work without a computer.

 

OH YUCK!! I guess that explains my rough shifts.

If I swap it for a TH350, will it handle the likes of a larger engine with lots more horsepower?

Is there a work around versus installing a different tranny???

 

There is actually a lockup kit for the 700r4 which is what the older cars like mine came with that is vacuum controlled.

Looks like this


If your car is an 82 it should have this older setup.
If you don't have this, it can be had on Jegs or Summit. You don't need the computer to control the trans.

If you go to a th350 you will not have overdrive (4th gear).

As far as bad shifts, you may want to check your TV cable adjustment also.

 

Hmmm...I always thought that I had the 700r4 Hydromatic...but what you just mentioned throws me off. I don't have overdrive...just P/R/N/D/2/1.

I'll get under it when the rain slacks off & get the code off of it. I guess I'll check the gears while I'm there, too. If I'm swapping transmissions, might as well look into gears (I never upgraded to 3.73 because I thought that was too much for my tranny.).

 

They'll work fine with properly applied electricity.


No, it doesn't. The ECM doesn't control shift firmness or rpm. Just lockup.



[QUOTE]Originally posted by TA5LiterHO
[B]There is actually a lockup kit for the 700r4 which is what the older cars like mine came with that is vacuum controlled.
Looks like this


Nope. The 81-up and 80-up GM cars had ECMs, which is what controlled lockup. A setup like that was used on diesels, maybe.

 

If you have a 82 camaro it should have a 200c transmission not a 700r4. The 200c is not a overdrive transmission.

 

jmd:

"Nope. The 81-up and 80-up GM cars had ECMs, which is what controlled lockup. A setup like that was used on diesels, maybe."


Actually that is the way my 84 TA came from the factory and it had and still has a 700r4. The ecm controlled the computerized carb when it was in there, but not the lockup. The harness looks exactly like the one in the pic I posted.

Here's the description of the harness:

"Now you can control the lockup converter on your overdrive transmission with your carburated engine and not have to buy an expensive computer! This easy to install Lock-Up Kit doesn't need the computer or speed sensor. A vacuum controlled 4th gear pressure switch/lock up solenoid combination controls the lockup. Comes with 4th gear pressure switch, converter lock-up solenoid, vacuum control switch, brake control switch, color-coded wiring harness, factory connectors and trans pan gasket. Fits any 700R4 GM transmission."

 

Since every single 83 & 84 LG4 / L69 car I've dealt with has ECM lockup including 2 that I own, I would have to say that I believe your car to be previous owner modified.

Based solely on what I've seen in my time on this earth.

But they did use a method or two for non ECM apps (Canada, Diesel,) so your statement at least makes me wonder a bit. Any further info on your car?

 

I wasn't saying you were incorrect. Just explaining how my car came from the factory. I bought the car from it's original owners about 5 years ago now with 37000 miles . I have known the original owners most of my life and nothing was modified from stock on the car until it came into my possesion including the original tires. The car was originally purchased off the showroom floor at Palm Pontiac in South Florida.

The car was built in Van Nuys. It is originally an L69 HO TA with the 30 spline 700r4.

GM may have used this vacuum lockup harness along with the ECM to activate lockup in this car. I am unsure. I have not used a lockup converter since I changed engines and disconnected the computer. (Computer is still in the car though)

All I know is I have the exact same harness pictured and it has GM markings and was in the car from its inception.

You have me thinking now also. Hmm. I have not seen this setup in the other thirdgens I have delt with.

 

Some of the vaccuum diagrams I have seen for our Canadian cars make reference to a vaccuum switch located on the firewall to control the transmission. All of my thirdgens (so far) have been 5-speeds, so I can't say for certain how it's hooked up.

 

I just switched to a carb in my car. The computer is still pluged in and has power to it, its running all of my gauges so... dont want to yank it. My question is, my 700R4 came out of a 89 Camaro and I have it in my 89 Firebird now. Just drove it an hour and a half back home on the highway, didnt go over 70. But I did test it out driving around, coulnt really tell that there was that much of a difference going on with the trans. I migh need to go romp or somethin to test it out. Maybe the computer working off the other parts still connected to it is still running that 4th gear in the trans. So, when you disconnect the computer all that happens is your 4th gear doesnt lock up right? It still connects, just not with a complete lock up with dirrect power transfer right? If thats all then... why cant you just leave it as it is? How much are you actually loosing here?

Incase anyone wants to know where to buy one. The cheapest I saw was at Jegs, 76 bucks.
http://www.jegs.com/cgi-bin/ncommerc...06&prmenbr=361

 

Nope. Until '90 TPI models, the VSS signal didn't even go through the ECM so not even the speedo is computer-run. All the gauges use normal sending units.


Without lockup, the 700-R4 tends to fail due to heat. Definitely something to address soon. The only ECM controlled item with your trans is the lockup. Not 4th.

 

sure about that? I've had to order an electronic speedo sender from the dealership. Was kinda hard to find because they only made that part for the last 4 months in production, so the dealer says.

Your probably right about the trans, I need to look further into that.

Just found this

https://www.thirdgen.org/newdesign/t...ueswitch.shtml

>Would this be any more harmfull then just leaving it as it is?
What would happen if you fliped the switch on or off while driving? going lets say about 50.

 

Well, I try & be 99% sure before I post something.

Since birds had an elec. speedo sender (gear driven, but outputs an elec. signal from the trans.) in 86-onwards and Camaros used them 90-onwards, I don't see how you got a part from the last 4 months of production.

You might see the rpm come down. Going 50, it won't hurt anything. Over-use, esp. in dragracing might eventually wear out a stock TC clutch. I would prefer to do something more "automatic" for street driving than that setup.

 

thats what it is, it does have a gear but an electric sender, right on.

 

I'm glad I clarified. :lala: