TH125 to any modern manual transmission ? (Page 1/1)
LeoLeChat MAR 28, 05:59 AM
Hello Everyone,

I was wondering if it's possible to get ride of my old TH125 and install a modern manual transmission of any kind (on my GT 88 ?) ? I still have the L44 2.8 V6 engine.

I live in Europe, pieces are rare and I won't be able to sell my GT to buy another Fiero with a manual transmission so I have no choice to make a swap or to keep the TH125 and I don't want to put another engine just to have a manual transmission.

Thanks !

[This message has been edited by LeoLeChat (edited 03-28-2022).]

Dennis LaGrua MAR 28, 06:23 AM
The GM 4T60 is nearly a bolt in transmission swap and was used on many GM cars. Do not confuse it with the 4T60e version as that needs a compatible ECM to shift it. Later on I'll post the applications here.
OOPs sorry missed the mark.
For a stronger manual transmission the F23 seems to be the choice. If you do a search info on swapping one in can be found on this forum

[This message has been edited by Dennis LaGrua (edited 03-30-2022).]

Steel MAR 28, 07:12 AM
A lot of people have installed 92-94 HTOB Getrag 5 speeds but these aren't considered modern any longer of course and only offer a slight upgrade overall than the standard Fiero getrag 5-spd trans

Otherwise F23 5 Speed, and the F40 6 speed are very nice options to modernize your Fiero to a manual trans.

Here's a link to Fiero guru's site: http://fieroguruperformance.com/?page_id=906

He may have the install parts to sell you in stock as well. He's a super busy guy so sometimes you might need to wait, contact him he's one of the absolute best in the Fiero community.
LeoLeChat APR 13, 04:21 AM

quote
Originally posted by Steel:

A lot of people have installed 92-94 HTOB Getrag 5 speeds but these aren't considered modern any longer of course and only offer a slight upgrade overall than the standard Fiero getrag 5-spd trans

Otherwise F23 5 Speed, and the F40 6 speed are very nice options to modernize your Fiero to a manual trans.

Here's a link to Fiero guru's site: http://fieroguruperformance.com/?page_id=906

He may have the install parts to sell you in stock as well. He's a super busy guy so sometimes you might need to wait, contact him he's one of the absolute best in the Fiero community.




Thanks, I'm gonna check that. Maybe I'm gonna keep my TH125 till it break.. Since there are not many Fiero in France, I think that I will keep it as vanilla as possible.
Iain APR 13, 04:34 PM
I’m in Scotland Leo, I have a 5 speed I’ll be taking out in about 3 months, if you know anyone visiting the UK I can get it to the London area .

iain
theogre APR 13, 06:38 PM
switching to stick is a very big job...
Besides the trans you need (Highlights):
Axles
shifter parts
hydro clutch parts
wiring changes
PROM/MEMCAL for the ECM
correct Flywheel for the engine. 88 V6 can't use same FW as older Fiero and other cars.

TH125c is 3 speed auto with Torque Converter Locking.
4T60 has overdrive but needs axles and wiring changes for TC Locking because isn't PnP item.

TC Locking will save gas mostly for "highway" driving.
In city driving often can't drive fast enough to lock (Lock above around 35mph 56kph) but Stick cars often Don't save gas in the city either regardless of popular myths.

Test for TCC locking... drive above speed, like 55mph/88kph and very lightly push brakes while carefully watching the tach.
Do Not to this test with people following you or cameras around or can have legal problems.
Lock trans will unlock with brake lights On and see a tach change around 200RPM Up/Down as tap the brakes the release.
If you don't see this... Many unplug the trans (in the front) because locking solenoid is bad. Other problems happen too but look for this issue first.

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