I'm looking to buy a used automatic transaxle and someone claims he has one with codes 6CPC and TGST on it.

I don't see any of these codes on this site: http://www.calgaryfieros.com/OSGdocs/tranny.html

Can you tell by these codes what's the final drive ratio? Is it really from a Fiero? Thanks.

[This message has been edited by cebix (edited 07-30-2019).]

The code 6CPC does not appear in the NIFE Enthusiasts Guide.

The code 7CPC appears as the trans for the 87 V-6 cars.

Do you think it's possible that this number just wasn't catalogued yet or can this transmission not be from a Fiero?

I don't have info to answer that with accuracy.

To check the FD ratio pull the speedometer sensor and look at the color of the gear. For instance a blue gear will be on a 3:33:1 FDR transmission, a white gear would probably be 3.18 but I've got to find the chart to give you exact numbers.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Fiero trans gears listed in my Cave, Gear Ratio
Other GM vehicles often have different gearing.

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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

Thanks guys. I'm acting only locally with this since the shipping cost is just too much. So I'll be throwing some ideas - glad if anybody could help.

There's a TH125C near me for sale from a 1990 Grand Am 2.5. Are these a direct swap? Only readable number is 90 PNC 156364.

Thank you.

[This message has been edited by cebix (edited 07-31-2019).]

Should be same but may have a different plug etc for TCC or VSS.
Example: If new unit has Optical VSS then you have to charge most of governor to fit Fiero VSS.

Thanks. I have some photos of said transaxle. Does it look like an optical sensor? Can you tell just by the photo should it fit the '85 2.5 Fiero?

Bought it. Will see if it fits and works soon. Will post if it needs any modifications for future reference.

It should fit, but gear ratio may be different.

Got a better look at the transaxle and there are some differences.

The dipstick along with the tube is twice as long.
The upper vent tube is just a tube going nowhere where as in the Fiero there was a little cap there. Should I put some kind of one way valve on it or a filter?

[This message has been edited by cebix (edited 08-04-2019).]

If you already have a TH125C, you should be able to use the dipstick and tube from it.

Anybody has any ideas about these differences? I attach a photo of an original THM125C from a Fiero and the differences in my Grand Am transaxle.

1. The electrical connector is 180 degrees out of the original one. Is that a problem?
2. The cooling lines - the upper original cap is just a tube here. The lower ones where they go to the radiator - one is blocked off. What should I do about this? Is this original?

Here's an original:



And here's my Grand Am one:





Thanks.

[This message has been edited by cebix (edited 08-06-2019).]

I found these bulletins showing the differences. Does it really matter in this situation? Can I leave the upper tube just in the air? Parts 404, 405.

Fiero:



Grand Am:

[This message has been edited by cebix (edited 08-07-2019).]

The blocked off cooling line is just pinched off when it was cut.
Your Fiero cooling lines should transfer over.
The NSS (Neutral Safety Switch) and select arm will transfer over from the Fiero.
If you can change the vent tube, go for it,if not, I don't think it would be a problem.

Unfortunately I don't have the NSS and the gear selector arm from my original transmission. Won't these found on the Grand Am transaxle bolt up to my original cable?

[This message has been edited by cebix (edited 08-07-2019).]

I don't know, as I am not familiar with the way the Grand Am shifter is set up.

Perhaps someone with more knowledge will chime in.

A little update. Cables attach good but the selector is backwards, totally messed up. D is P, N is R, R is N, P is D and you can't go forward anymore, you get the idea.

Can I somehow modify this to work correctly in the Fiero? I don't have my original gear selector arm and NSS and not sure I can buy one locally.

Thanks.

[This message has been edited by cebix (edited 10-07-2019).]