Fiero TH125 transmisison issues (Page 1/1)
jjd2296 DEC 09, 09:17 AM
Looking for some input on this one. I have a NOS TH125 transmission installed in a new 3.4 sc build. The NNS is set correctly, and i have adjusted the TV cable. Car starts and shifts but no gears engage, interior shifter shifts fine, no issues, I can shift it from the transmission side as well into all gears. It goes into neutral and rolls no problem. I double checked the fluid levels and took a little out. Could it be my governor? I read that if the governor is not installed correctly it wont engage gears at all?

I did have to swap governors as the one in the car was made for a 1991 lumina van as its a newer model TH125. maybe I did something wrong?
82-T/A [At Work] DEC 09, 09:54 AM

quote
Originally posted by jjd2296:

Looking for some input on this one. I have a NOS TH125 transmission installed in a new 3.4 sc build. The NNS is set correctly, and i have adjusted the TV cable. Car starts and shifts but no gears engage, interior shifter shifts fine, no issues, I can shift it from the transmission side as well into all gears. It goes into neutral and rolls no problem. I double checked the fluid levels and took a little out. Could it be my governor? I read that if the governor is not installed correctly it wont engage gears at all?

I did have to swap governors as the one in the car was made for a 1991 lumina van as its a newer model TH125. maybe I did something wrong?




The only advice I can give here, is the only time an automatic transmission doesn't run, is if it isn't getting any fluid and thus the hydraulics aren't doing hydraulic things.

There's a dozen or so check balls of course, so I assume all of thosee are where they are supposed to be. But have you checked the pan? If the filter isn't affixed with the correct bracket (and it drops out into the pan), it won't be sucking up any fluid... it's the only thing I can think of. None of the other things would cause it not to run. Sometimes though... these transmissions, if they've been sitting for a while (especially if it's NOS and has had no fluid in it), stuff might be stuck in it and not pumping fluid properly. I bought a 50k mile C4 Corvette that sat for like 7 years. I got it running, but the transmission wasn't shifting, or even going into gear. After moving it in drive and reverse several times, it finally broke everything free again and now it drives.

Sorry, I know that's not hugely helpful, but that's my thought...
sleek fiero DEC 09, 10:10 AM
sounds like the pump is possibly cavitating possibly because the converter was not filled before install. sleek
Dennis LaGrua DEC 09, 01:24 PM
I would keep checking the fluid level when the engine is hot as per the manual. Was the 36 yr old transmission rebuilt as claimed? If you decide to take it a step further use a TransGo shift kit not the B&M brand. Makes a huge difference.

------------------
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"THE COLUSSUS"
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[This message has been edited by Dennis LaGrua (edited 12-17-2024).]

jjd2296 DEC 09, 01:39 PM
thanks guys ill check both of these things.