6 cyl 5-spd/ 4cyl 5-spd

[Dr. Sievers]

Hi, I am new to the fiero. I used to do japanese imports but I got so tired of having to drive along next to about three or four fart cans and I demolished my 93 MR2 so I figured I'd try out Pontiac's mid-engined delight, and so far I love it! I was planning on doing a 3800sc budget minded swap to the vehicle and I ran across one little snag. I noticed that in every swap leg I've read, there was one variable that was common, each person had used the 6cyl's 5-spd trans and not the 4cyl. I wanted to know if there is any difference between the two? From everything I've come across (which isn't much) the trans are the same but I need to be sure first.

 

[Oreif]

No, They are not the same.
The 4-cyl (1985 thru 1988) uses an Isuzu 5-spd transaxle with a 3.35 final drive ratio.
The 6-cyl (for late 1986 thru 1988) uses a Muncie-Getrag 5-spd with a 3.61 final drive.

The getrag has a much stronger case and has been used with modified 3800SC's and Chevy V-8's.

The Isuzu's tend to eat 3rd gear then the diff blows out the side of the case when used with high horsepower engines.

 

[Here4u2hate]

The manual trans in a fiero will fit: 2.5, 2.8, 3.1, 3.4, 3.4 DOHC, 3800, 3800SC, 4.3, 4.5 Northstar, 4.9 Northstar, 305sb, 350sb, and 400sb

 

[Dr. Sievers]

No, They are not the same.
The 4-cyl (1985 thru 1988) uses an Isuzu 5-spd transaxle with a 3.35 final drive ratio.
The 6-cyl (for late 1986 thru 1988) uses a Muncie-Getrag 5-spd with a 3.61 final drive.

The getrag has a much stronger case and has been used with modified 3800SC's and Chevy V-8's.

The Isuzu's tend to eat 3rd gear then the diff blows out the side of the case when used with high horsepower engines.

For a budget minded swap would it be sufficient for about a year until I could afford the getrag? Or am I better off holding onto my money driving on my iron duke and doing it all at once?

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[my04gt]

do it all at the same time if you can that way you have not done the work and then a weer later need a new trany

 

[Oreif]

The manual trans in a fiero will fit: 2.5, 2.8, 3.1, 3.4, 3.4 DOHC, 3800, 3800SC, 4.3, 4.5 Northstar, 4.9 Northstar, 305sb, 350sb, and 400sb

No, that is incorrect. The Fiero transaxles use the small BOP bolt pattern.
The 4.3L and any small block chevy V-8 uses the Chevy pattern.
In order to swap in a SBC or a 4.3L you need an adapter plate to mate it with the transaxle.

Generally if the engine has been used in a FWD configuration it has the BOP bolt pattern. The 4.3L and nearly all SBC V-8's have never been used in FWD.
(The LS4 is the only SBC V8 used in a FWD platform in the Grand Prix GXP and has the BOP bolt pattern for that engine only. The other 5.3L engines use the Chevy bolt pattern.)

 

[Oreif]

I recommend going to the getrag 5-spd right from the start.

BTW ~ You can also use the F40 transaxle from a Pontiac G6. This will give you a 6-spd transaxle and it is stronger than the getrag.

 

[Dr. Sievers]

I recommend going to the getrag 5-spd right from the start.

BTW ~ You can also use the F40 transaxle from a Pontiac G6. This will give you a 6-spd transaxle and it is stronger than the getrag.

I'm sorry I don't know the F40 transaxle... is it a 6-spd standard transaxle or is it an auto-stick? I really have to have a clutch it's very important to me. I don't feel comfortable in an automatic. I am obviously not too familiar with GM products, I am coming from TRD and Nismo cars and I am having to learn a whole lot of new stuff. Surprisingly enough, the Japanese cars don't wave from eachothers engineering styles much. Subaru is about the only one that really heads their own direction.

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[Oreif]

I'm sorry I don't know the F40 transaxle... is it a 6-spd standard transaxle or is it an auto-stick? I really have to have a clutch it's very important to me. I don't feel comfortable in an automatic. I am obviously not too familiar with GM products, I am coming from TRD and Nismo cars and I am having to learn a whole lot of new stuff. Surprisingly enough, the Japanese cars don't wave from eachothers engineering styles much. Subaru is about the only one that really heads their own direction.

The F40 is a 6-spd manual transaxle. It was only used in the Pontiac G6's.

The G6 6 speed is just ¼” longer that the Fiero Getrag transmission. The end of the trans that is the closest to the left side frame rail is larger in profile because that transmission has 3 gear shafts instead of the Fiero’s 2 shafts.

The swap can be very affordable if you can obtain parts at a salvage yard. However, the G6 just started using the 6 speed in 2006. This may make them a hard to find in the salvage yards. Optionally, you can find them on Ebay for $400 or $500 each. They can also be purchased at your local GM dealer parts department(at about $1850.00 each).

Other parts you need to do the swap:
6 Speed Shift Cable Mounting Brackets
Intermediate Shaft for 6 Speed G6 Transmission
Left Side G6 Axle Assembly
Right Side G6 Axle Assembly
G6 Hyd. Clutch Line Fitting Check Valve
You will need to use a 4 speed Fiero shifter and you will need to use 2 Fiero Getrag Select Cables on this swap.

 

[Dr. Sievers]

Other parts you need to do the swap:
6 Speed Shift Cable Mounting Brackets
Intermediate Shaft for 6 Speed G6 Transmission
Left Side G6 Axle Assembly
Right Side G6 Axle Assembly
G6 Hyd. Clutch Line Fitting Check Valve
You will need to use a 4 speed Fiero shifter and you will need to use 2 Fiero Getrag Select Cables on this swap.

is there anyway I can just use the G6 shifter or a universal short throw with this?

 

[Oreif]

is there anyway I can just use the G6 shifter or a universal short throw with this?

Not sure if you can modify the G6 shifter. For a short shifter, The Fiero Store sells a short throw shifter that fits the 4-spd frame.