82 Overdrive
Thread Starter
Melting Slicks
Joined: Apr 2023
Posts: 2,802
Likes: 1,623
From: Poplar Bluff MO
82 Overdrive
The 82 I just bought has the CF removed, I've been reading that the 82 has a 3 speed automatic with overdrive but the overdrive function is controlled by the CrossFire ECM. Is there a way to restore the overdrive?
https://www.corvsport.com/1982-c3-corvette/
Or how do you tell if the transmission is in overdrive?
JT
Designated 700-R4, the four-speed automatic was basically a variation of the three-speed Turbo-Hydra-Matic with a long striding overdrive fourth gear added on. The 700-R4 automatic was electronically linked to the car’s ECM (Engine Control Module). Shifts and the torque converter’s lockup clutch feature were precisely controlled by the ECM, depending on varying speed and load data inputs.
As before, there was a torque converter lockup effective on all forward gears except first. It used a higher first gear ratio (3.07:1) for improved acceleration.
This synchronization between transmission and ECM was one of the most advanced setups ever developed for use in any Corvette to that point.
As before, there was a torque converter lockup effective on all forward gears except first. It used a higher first gear ratio (3.07:1) for improved acceleration.
This synchronization between transmission and ECM was one of the most advanced setups ever developed for use in any Corvette to that point.
Or how do you tell if the transmission is in overdrive?
JT
Last edited by jthornton; Aug 29, 2024 at 04:49 PM.
Melting Slicks
Joined: May 2021
Posts: 2,271
Likes: 1,316
From: Fleming Island, FL
4th gear (OD) is hydraulically controlled and the converter lockup is ECM controlled. If you no longer using the ECM for converter lockup TransGo LU-700 lock up kit works really well. No wiring or electrical, it's all hydraulic. Use the diesel spring set up.
Burning Brakes
Joined: Feb 2020
Posts: 904
Likes: 569
From: Central NJ
Hi, I also have an 82 with the X-fire removed. The ECM only controlled the Torque convertor lock up for fuel economy reasons. The shifting was done via throttle position moving the TV cable which adjusts the trans pressure and also the servo & governor. You should feel three distinct shifts, 1-2,2-3,3-4 and once in 4th you can feel the torque convertor lock up if there is something to make that happen since the ecm no longer controls that... There are kits on the market, B&M makes one, I use a 4th gear pressure switch. How does your shift feel...
60
60
Thread Starter
Melting Slicks
Joined: Apr 2023
Posts: 2,802
Likes: 1,623
From: Poplar Bluff MO
Thanks for the replies.
I drove it about 75 miles to get it home and didn't notice anything odd about the shifting. I was concentrating on getting it home in one piece as the brakes were very marginal and no rear brakes at all. IIRC the RPM at 65 was some where around 2k or so.
JT
I drove it about 75 miles to get it home and didn't notice anything odd about the shifting. I was concentrating on getting it home in one piece as the brakes were very marginal and no rear brakes at all. IIRC the RPM at 65 was some where around 2k or so.
JT
Thread Starter
Melting Slicks
Joined: Apr 2023
Posts: 2,802
Likes: 1,623
From: Poplar Bluff MO
Hi, I also have an 82 with the X-fire removed. The ECM only controlled the Torque convertor lock up for fuel economy reasons. The shifting was done via throttle position moving the TV cable which adjusts the trans pressure and also the servo & governor. You should feel three distinct shifts, 1-2,2-3,3-4 and once in 4th you can feel the torque convertor lock up if there is something to make that happen since the ecm no longer controls that... There are kits on the market, B&M makes one, I use a 4th gear pressure switch. How does your shift feel...
60
60
JT
Thread Starter
Melting Slicks
Joined: Apr 2023
Posts: 2,802
Likes: 1,623
From: Poplar Bluff MO
This TransGo 700-LU kit fits 1982 to 1993 General Motors vehicles equipped with the 700R4/4L60 automatic transmission. This kit will fit both Type-1 or Type-2 valve bodies as long as the valve body is factory machine to accommodate the new TCC shift valve and TCC shift TV bushing.
I really appreciate the help guys.
JT
Melting Slicks
Joined: May 2021
Posts: 2,271
Likes: 1,316
From: Fleming Island, FL
The thing I like about this kit is it raises the 4th gear shift point and delays converter lockup after the 4th gear shift. The bored hole in the valve body is like GM originally intended for these transmissions to have hydraulic converter lockup.
Burning Brakes
Joined: Feb 2020
Posts: 904
Likes: 569
From: Central NJ
Are you using something like this?
If I get around to dropping the pan for a filter change I might switch to Skid's solution, I am not sure what vintage my trans is and I don't want to get into changing valve bodies so Im not sure. The B&M kit is adjustable and looks interesting, I was told by a trans guy I know that they can be troublesome but he did not elaborate...
For now my fluid is pink and it shifts well so I'm not going to tinker...(for once-lol)..
60
Last edited by 1860army; Aug 30, 2024 at 08:25 AM.
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Drifting
Joined: Aug 2019
Posts: 1,510
Likes: 498
I would do a B&M Lockup controller , I've done those Trans Go valves and as soon as it hits 4th gear Lock up applies and it's like shifting two gears up at once and if you have any camshaft at all it will lug the engine , Trans Go also makes a TCC eliminator kit that corrects cooler flow for those that choose not to use Lockup at all because the Cooler flow is restricted if the TCC is not used so the Trans Go eliminator kit corrects the flow to the cooler
Melting Slicks
Joined: May 2021
Posts: 2,271
Likes: 1,316
From: Fleming Island, FL