I have a 1988 Fiero GT Auto. What rpm should the transmission shift at from 1st to 2nd when floored?

quote Originally posted by pelensky: I have a 1988 Fiero GT Auto. What rpm should the transmission shift at from 1st to 2nd when floored?

I have the exact same question. Weird you have not gotten a response. When I refreshed my 88 twelve years ago. I bought a rebuilt transmission from someone here on PFF. It has performed well with the the one exception- The transmission shift points seem to be at quite low rpms. I tried working on it after it was first installed, but could not find anything wrong. It just shifts too soon. While driving it yesterday I was accelerating at full throttle from stop. I happened to look at the tach when it shifted. Maybe 3,000 rpm. So, so far away from redline. [sigh]

On the bright side I have no concern of over-revving.

Shift points can be altered by adjusting the transmission's TV cable.
It can be "trial and error" to find the shift points you want.
http://web.archive.org/web/...~fierocave/th125.htm

Depressing the D shaped button can be hard at times.
I think I placed a nut on it and used pliers to get it working.

See Fierobsessed comments here:
https://www.fiero.nl/forum/A...090907-2-093280.html

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quote Originally posted by fierosound: Depressing the D shaped button can be hard at times.

For sure. I had one heck of a time adjusting the TV cable on my '86 GT for that very reason. It was worth the battle though as the adjustment was previously way off.

The one time I tried to adjust the TV cable I also had a time with the button. That said, I think I will try again. I don't want to run my old engine near redline, but it sure seems it should get closer than 3,000 rpm before shifting at full throttle.

One thing-

Fierobsessed- "To adjust the TV cable, you open the throttle all the way, then press the button on the cable adjuster and pull the cable away from the throttle body all the way till it stops. Make sure the throttle is all the way open when doing this. Then release the button."

Ogre cave- "It takes considerable effort to make the TV cable adjuster move. Do Not press the accelerator pedal to make the adjustment or you'll likely damage the throttle cable or other parts in the system, especially in Fiero with it's snake of a cable.."

Not having looked at this thing in over a decade I cannot remember, but I assume the difference between the two statements is Ogre is referening the accelerator pedal whereas Fierobsessed references having the throttle all the way open. I assume those statements fo not conflict. I just need to hold the throttle open when attempting TV cable adjustment.

I have adjusted the tv cable properly and it is tight at wide open throttle. I was just curious what people see.

quote Originally posted by pelensky: I have a 1988 Fiero GT Auto. What rpm should the transmission shift at from 1st to 2nd when floored?

This is question I would like an answer to. Of course, it is a ballpark figure. I just want to know if it is reasonable for mine to shift at 3,000 rpm at full throttle.

When I got my '87 GT running, the auto trans would not shift out of 1st at all. Discovered quickly that the TV cable was the wrong one as the end was hanging out of the throttle wheel about three inches, proper adjustment was impossible. I shortened the cable and installed a barrel clamp and after much finagling, got the trans to shift properly. I was amazed on how much difference in shifting resulted in very small increments of adjustment.

quote Originally posted by creaky78: In answer to the original question, I drove the GT today, full throttle shift from 1st occurs @ 5500-5800 RPM.

Thank you, Thank you! I realize it is a ballpark, but it says my 3,000 rpm shift point is way too low. I will try adjusting the TV cable again.

quote Originally posted by fierosound: Shift points can be altered by adjusting the transmission's TV cable. It can be "trial and error" to find the shift points you want. http://web.archive.org/web/...~fierocave/th125.htm

Adjusting TV only Minorly change the shifting points.
You set the TV cable as said in cave and stop. But watch this because many adjusting parts have dirt or worse causing adjustment binding and you adjust w/o checking can strength or break the TV cable. Adjuster "Tubes" should slid easy w/ you pushing and hold the button. Button should push in easy too. But either or more likely both have problems and you adjusting can be far worse for the trans. You might "play by hand" to adjust more but cable/trans doesn't like you moving adjuster more then 1-2 clicking one way or other. You "adjusting" Way more in/out can break the cable or won't shift.

Late or even no shift is often:
Governor Problems. It can get plug w/ dirt partly or completely. Can have bad springs etc. or wrong parts if came from other cars.
Valve Body problems. Any to all passages can have same as above w/ dirt.

"Max Throttle" is often wrong because gas pedal and cable are screwed up on many Fiero.
See my Cave, Throttle Cable

1-2 shift could be late at or near WOT anyway because TV and Gov makes this happen for TH125c. They are only thing "Setting" values for engine loads vs car speed. Isn't like 4T60 etc w/ vac mod that tells the trans some "data" for engine vacuum used.

Car likely has a lot of miles on 30+ year old Dexron II fluid doesn't help. If anyone simply pan drop to change oil doesn't get enough old oil to really matter. "Flush" a trans to change oil can cause big problems.
GM no longer Makes or License Dexron III fluid but manufacturers still claim whatever product they offer = to that.
Dexron VI and later is current GM license product I think but often can't find at most retailers.

If some fool install a "trans kit" then all bets are off because many are installed wrong.

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