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Topic: 4/3 OD issues

in Forum: C4 Driveline Components

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4/3 OD issues (1/3)
 9/7/16 10:07pm
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Burlington, NC - USA

1986 coupe, red, gray leather interior, 350 L98, Doug Nash 4/3 transmission

Joined: 7/17/2016
Posts: 4

    I have an 86 with the 4/3. Overdrive stopped working. I changed the fluid, filter & relay - nothing. I ran 12 volts to the ALDL F terminal & the yellow OD light comes on. I have researched various forums & have read about ways to bypass the ECM, but they can be somewhat confusing. I read in one article that you can use a jumper wire on the second gear switch.Another talked about doing it at the ecm, still another said you could do it at the relay.  Is there a place to get a replacement solenoid & pressure switch if needed ? Sorry about being so long winded. Any help would be appreciated as I'm totally frustrated.

|UPDATED|9/7/2016 8:07:17 PM (AZT)|/UPDATED|
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Re: 4/3 OD issues (2/3)
 10/1/16 5:12pm
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Sebring, FL - USA

1987 Red Roadster Automatic (SOLD 4/4/23) it will be missed. 2004 Yellow Coupe 6 speed 2014 Red Convertible Z51 3LT

Joined: 7/16/2016
Posts: 18

Last month my 87 dropped out of OD when on a long trip highway trip from Corvettes at Carlisile in PA to Bowling Green KY. in Huntington, WV where we stopped for the night. The following morning the OD worked fine and we continued on our way to KY but while in cruise control just outside Lexington, KY the tranny dropped out of OD with  loud bang and then was blowing heavy smoke out the back of the vehicle. We had to be towed, the tranny needed a total rebuild as there was metal in the oil. My suggestion to you is get it checked professional NOW before you get a LARGE bill.

The rebuild replaced the planetary and the clutches and the torque converter now it shifts and responds to the throttle as it should. The car only had 83000 miles when this happened.

|UPDATED|10/1/2016 3:12:11 PM (AZT)|/UPDATED|
Re: 4/3 OD issues (3/3)
 8/9/20 2:39pm
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lancaster, CA - USA

1984 but looks like what gm should have made it look like

Joined: 7/17/2020
Posts: 6

I have the factory manual for such issues. More than likely the clutches are burnt. Does reverse work? Eckles just now listed rebuild kits $259.

 The overdrive was designed in retro spec of the old chevy power glide trans, just put in a different case and added a soliniod.

A good trans shop can cross referance the parts and do the rebuild. hope you got lots of $.


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