AUTOMATIC TRANSMISSION (Page 1/2)
belldan MAY 28, 05:40 PM
Good Day Everyone ! I'm considering purchasing an 85 through 88 Fiero GT with an automatic transmission. It's my understanding that the most common transmission is a TH-125. Should I ever need a replacement transmission, please advise if they are readily available along with the best place to purchase one. Thanks everyone for your time!
fierofool MAY 28, 06:47 PM
All automatic trans Fieros used them as well as a large number of GM cars that had 60 degree V6's. If you ever had a failure and wanted to upgrade a little, the 4T60 transmission, non-electric, would give you a better gear ratio plus an extra gear.
82-T/A [At Work] MAY 28, 07:24 PM

quote
Originally posted by belldan:

Good Day Everyone ! I'm considering purchasing an 85 through 88 Fiero GT with an automatic transmission. It's my understanding that the most common transmission is a TH-125. Should I ever need a replacement transmission, please advise if they are readily available along with the best place to purchase one. Thanks everyone for your time!




Like FieroFool said... the 4T60 will practically drop right in with no modifications unless you've got an 88, in which case you have to slot the frame.

https://www.pontiacperforma...es/4_Speed_Swap.html


But yeah, the Th-125C is very common...
belldan MAY 29, 09:36 AM
Thanks so much for the information! Kindly advise if the automatic transmissions are readily available along with the best place to purchase. Thanks again!
theogre MAY 29, 01:04 PM

quote
Originally posted by belldan:
Should I ever need a replacement transmission, please advise if they are readily available along with the best place to purchase one.

Finding TH125c or 4T60 is Not easy to get in many places now.

Many areas the City etc have Forced most junk yards Closed or majorly change how they operate for environmental, fire & more problems. (That's completely ignoring EV & Hybrids now causing fires @ junk yards etc. dealing w/ the LiIon batteries after a wreck.)
Even before that Many junk yards simply don't keep most vehicles > 15-20 years & go to the crusher.

Not easy or cheap to get a Rebuilt Unit either...
1. Not enough good Cores to rebuilt.
2. Even if get cores, many don't see enough demand to bother rebuild then sit in inventory for months to years.

Even many internal parts aren't easy to get now.
You have TH125c but exact year made maters because the chain & sprockets changed 1 or more times over the years. Other internal parts have change too & often can't use parts made for X years in your unit.
Year of the Transmission often Not = to Year of Car so a Shop etc Need the Tag Data on the unit before trying to get parts.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

belldan MAY 29, 05:25 PM
Thanks very much for the information regarding Fiero automatic transmissions. Since the transmissions and components are becoming harder to find, it appears that it might be best for me to purchase a manual. Kindly advise as to your thoughts regarding manual transmissions and are the clutches and components hard to find. Thanks again !
Patrick MAY 29, 05:31 PM

quote
Originally posted by belldan:

...it appears that it might be best for me to purchase a manual. Kindly advise as to your thoughts regarding manual transmissions and are the clutches and components hard to find. Thanks again !



Best decision you could ever make when buying a Fiero. So much more fun to drive, better gas mileage, more power to the ground, etc etc. Clutches are readily available, and will last a very long time with a stock engine.
theogre MAY 29, 09:45 PM

quote
Originally posted by Patrick:
Best decision you could ever make when buying a Fiero. So much more fun to drive, better gas mileage, more power to the ground, etc etc. Clutches are readily available, and will last a very long time with a stock engine.

This hype train again.... I've driven a lot of sticks to know the Truth.
"So much more fun to drive" often Not. Worse in areas w/ heavy traffic.
"better gas mileage" only when driving on highways etc that allow running in top gear vs TH125 w/o an Over Drive. 4T60 is often = to any stick car. In the "city" nearly all stick drivers have poor shifting &/or keep in X gear way sooner later or both for whatever reason (like often to stop shifting every few yards) canceling MPG "advantaged" @ best.
"more power to the ground" depends on total gearing & more. The Torque Converter can add 1.5-1.9 times over Torque off the engine crank but many TH125 have higher "finals" then some Stick cars. Many 4T60 setups can easily beat most 4 & 5 speed factory sticks.

Example: If have heavy traffic causing stop&go a lot will often hate the stick fast. Like driving on Schuylkill Expressway in PA at most times. Worse Fiero & more will break the Diaphragm Spring in the Pressure Plate way faster because of metal stress from that driving.

Then add other problems w/ stick Fiero & hydro clutch "linkage" etc posted a lot here alone.
& that's ignoring many stick are driven to the ground & have problems too like many leak oil @ axle seals because early sign of bearing failure of the dif.

TH125c/3T40 & 4T60 have their own problems but can last 200,000 or more mile if not abused.

Face Facts. Any 30+ year old car has problems now or soon. While some use Fiero as daily ride, isn't a good plan for a lot of others more so if they can't or won't work on them for Hundreds of Reasons. Worse many old cars have "upgrades" that often unsafe, illegal, etc & most buyers now have no clue what was done until too late costing huge $ to kill someone.
Patrick MAY 29, 10:01 PM

quote
Originally posted by theogre:

This hype train again.... I've driven a lot of sticks to know the Truth.



The "Truth" according to The Ogre. lol

I don't care what you or any other stick in the mud says... manual transmission cars are more fun to drive, for real car guys (or gals).

I actually have an automatic '86 GT, in very nice shape. It's been in storage for years. I bought it for temporary use ages ago while I was working on my swapped in 5-spd '84 Fiero. And then I also bought a 5-spd Formula. Both cars, even the four-banger, are so much more fun to drive than the '86 GT with the slushbox. There's absolutely no comparison!

[This message has been edited by Patrick (edited 05-29-2024).]

82-T/A [At Work] MAY 30, 08:35 AM

quote
Originally posted by theogre:
This hype train again.... I've driven a lot of sticks to know the Truth.
"So much more fun to drive" often Not. Worse in areas w/ heavy traffic.
"better gas mileage" only when driving on highways etc that allow running in top gear vs TH125 w/o an Over Drive. 4T60 is often = to any stick car. In the "city" nearly all stick drivers have poor shifting &/or keep in X gear way sooner later or both for whatever reason (like often to stop shifting every few yards) canceling MPG "advantaged" @ best.
"more power to the ground" depends on total gearing & more. The Torque Converter can add 1.5-1.9 times over Torque off the engine crank but many TH125 have higher "finals" then some Stick cars. Many 4T60 setups can easily beat most 4 & 5 speed factory sticks.

Example: If have heavy traffic causing stop&go a lot will often hate the stick fast. Like driving on Schuylkill Expressway in PA at most times. Worse Fiero & more will break the Diaphragm Spring in the Pressure Plate way faster because of metal stress from that driving.

Then add other problems w/ stick Fiero & hydro clutch "linkage" etc posted a lot here alone.
& that's ignoring many stick are driven to the ground & have problems too like many leak oil @ axle seals because early sign of bearing failure of the dif.

TH125c/3T40 & 4T60 have their own problems but can last 200,000 or more mile if not abused.

Face Facts. Any 30+ year old car has problems now or soon. While some use Fiero as daily ride, isn't a good plan for a lot of others more so if they can't or won't work on them for Hundreds of Reasons. Worse many old cars have "upgrades" that often unsafe, illegal, etc & most buyers now have no clue what was done until too late costing huge $ to kill someone.




I've had good luck with automatics in Fieros, and also manual transmissions. I've been lucky in that I've never actually had problems with a transmission in a Fiero.

BUT... the one problem I did have... the transmission cooler lines almost never get serviced. I bought a 1984 Fiero 2m4 SE, and took it on the highway. It had 98k miles, and looked amazing inside and out (it was a repaint, but well cared for). My single 40 minute highway drive caused the line pressure to split the transmission cooler line which sent a stream of transmission fluid directly at the catalytic converter... which created a smoke-screen for all of I-95, blocking out all 5 lanes. I only realized it, listening happily to my AM radio as an old-fart 21 year old, because I noticed not a single car had passed me... so I looked in my rear-view, and all I saw was a big cloud of white smoke.

I pulled off the highway, quickly found a bleach bucket on the side of the road and filled it with water from the canal... and put out the flames before the car became engulfed.


So I would add... the automatic transmissions have their own demons.

[This message has been edited by 82-T/A [At Work] (edited 05-30-2024).]