Which transmission is best (Page 1/5)
Corpsmen Ed JUL 09, 10:35 AM
Although I am still narrowing my engine swap choice down, I am leaning towards the 3800 SC. My car currently has the Iron duke with the 5-speed Isuzu tranny, and has about 90,000 miles.

Should I switch the tranny if I upgrade to the 3800 SC? I've heard the Isuzu isn't strong enough to handle the power.

I'd like to stick with the stick shift, but could be swayed for the Auto with a good argument.

But as for stick shifts, which is best?

The Muncie Gertag? (Which seems hard to find)
The F23? (I've heard this has strength issues as well.)
The F40? (Seems the costliest, and have heard that 3rd gear is too short and 4th gear too long.)

What are your opinions?
Gall757 JUL 09, 03:02 PM
Don't overlook the Muncie 4 speed M17. It seems to be as strong as any manual and you will have less need for a 5th gear with more power. The big plus is they are still relatively cheap.

[This message has been edited by Gall757 (edited 07-09-2013).]

dobey JUL 09, 03:12 PM

quote
Originally posted by Gall757:

Don't overlook the Muncie 4 speed M17. It seems to be as strong as any manual and you will have less need for a 5th gear with more power. The big plus is they are still relatively cheap.




The 5th gear on the Getrag/Isuzu isn't there because the cars have less power. It's there to get better MPG.
PaulJK JUL 11, 06:00 AM

quote
Originally posted by Corpsmen Ed:

But as for stick shifts, which is best?

The Muncie Gertag? (Which seems hard to find)
The F23? (I've heard this has strength issues as well.)
The F40? (Seems the costliest, and have heard that 3rd gear is too short and 4th gear too long.)

What are your opinions?



This question has been asked many times over the years and the general opinion has been that the muncie 4 speed is stronger than the 5 speed getrag; both of these are better than the isuzu, which is usually thought of as weakest of the bunch.

it is also generally agreed that none of these trans will hold up well if you frequently abuse them with a high horsepower/torque engine conversion. I have the 5 speed getrag with an L98 and have no trouble, but i drive it normally without abuse. Abusing with a 3800SC will ruin your clutch; doing it with a v8 will break the axles .

i've seen a few guys post that the F40 is a strong enough trans, but 6 speeds aren't THAT big of an advantage (due to the gearing you mentioned) and is outweighed by the higher cost.

My opinion is to go with the getrag 5 speed, don't power shift and don't dump the clutch. Gas mileage is good. With my car, 1st is about 3 seconds, 2nd is about another 5 seconds, then 3rd gear will carry you anywhere you wanna go.

FFIEROFRED JUL 11, 07:51 AM
What he said.
All the mantrans that will fit will have to low a 1st gear. so use a aluminum flywheel.
All the mantrans that were used in fiero's are OLD! and used up. Finding a good, low miles trany is a quest.

you want to drive it every day, beat on it, race it, get good mpg use the auto trans that comes with the engine. That and you get to use 2 hands to steer it when you are out showing your ass. the auto's are faster.
putting a 3800SC in a fiero is going from a under powered car to a over powered car.

I love a good stick shift. But their is only so much you can ask of a old, week, trany.
onesexyfiero JUL 11, 12:14 PM
I pulled the 128k getrag from my 88 that had a shot 3rd gear syncro and a bad seal at the input shaft bearing, both common problems. Threw a muncie in from an '86 parts car that had a hard 200,000 mile life, and 20k later, it still works perfectly. Granted, I don't abuse it, and its only behind a 200ish HP modified 3.4. 1st is nice and long enough to be usable. Not great for traffic. 4th turns 2,800 at 70, which isn't terrible. My sisters VR6 Jetta with a 6 speed manual turns the same rpm's in 6th. I don't find myself wanting more gears. It would be nice to have an overdrive 5th to nurse out a few more mpg's, but I can still get up to 29 on a long trip. It's also nice having it right in the power band when you've cruising at 70.
Silicoan86 JUL 11, 12:51 PM

quote
Originally posted by Corpsmen Ed:
The F23? (I've heard this has strength issues as well.)



I have not heard of any strength issues with the F23. In fact, it seems that the general consensus at this point is that this trans can withstand a very high level of torque. It does require a little fabrication and possibly some custom parts to install it, but IMO this is going to be the most durable of the transmissions that you listed.
dobey JUL 11, 04:24 PM
It depends on what you plan to do with your swap. If you want to keep it cheep, stick with the Isuzu until you break it. Despite what some have said, if you don't dump the clutch or shift into peak torque, you'll pretty much be fine with it for a while. And its 5th gear will give you the best MPG out of what transmissions come in the Fiero. You might want to throw a new clutch in the car though, as the original is probably still in it, and it's worn down.

If you want to upgrade a bit, and still keep costs down, the Getrag is a bit stronger, and a reasonably easy swap to do coming off an Isuzu. You still have OD 4th and 5th with it, so cruising MPG will still be good, though slightly less than the Isuzu.

If you plan to add a big turbo or anything to significantly increase the power output of the swap later on, then either go with the F23 or F40, or convert to automatic, and buy a 3800 with the 4t65 mated to it already, and throw that in there.

The auto will perform better for drag racing if you want to race it on the weekends at the strip or anything like that.
Justinbart JUL 11, 04:29 PM
F23 all the way.

------------------
Turbo 3800 E85 F23 5spd spec5
11.17@132.6

lateFormula JUL 11, 06:40 PM
The F23 is rated for input torque of 170 ft/lb.

The F40 is rated for input torque of 295 ft/lb.

One that hasn't been mentioned is the F35 which is a five speed manual gearbox that is rated for input torque of 260 ft/lb. This trans was used in the Cobalt and HHR SS models with the LNF engine and they all came from the factory with a limited slip differential.