Once the 20th show is over with I'm going to convert my car to a stick. Right now it's looking like my options are a 4 speed from a 86 SE or a 5 speed from a 85 coupe. I would rather have a 5 speed in the car, but I've heard the gearing doesn't match up very well. And likes to drop the engine out of the power band when you shift. I've also heard that the 4 speed was the quickest tranny offered in the fiero but the top end suffers a bit. The car is a 86 Se with a slightly worked over 2.8 I'm not sure if it has the factory cam in it. It doesn't like to make power until 2,400 RPM or so and then it drops off around 5,000. I'm just wanting your thoughts and opions on the better match for the car.
IP: Logged
04:34 AM
PFF
System Bot
West Coast Fiero Member
Posts: 2044 From: Los Angeles, CA, USA Registered: Jun 2001
Personally, I would go for the 4 speed Muncie built with the 3:32 gearset from the "high mileage" RPO MY8 '84 transmission. You would have the stoutest trans offered for the Fiero with the drivability of a 5 speed ( 2300 RPM at 75-80 mph )
5 speeds suffer from having the smallest carrier bearings out of all 3 manual transmissions from the Fiero, with the 5 speed Isuzu coming in second. Of course, $65.00 in bearings, races, and seals from Auto Zone ( Timken Set 11 ) will cure this.
But once again, that's just my opinion.
------------------ ( the above was the thoughts, views, and opinions of a disgruntled Fiero mechanic, and do not express or imply those of West Coast Fiero, Fieros West, or any other organization - just that of this poor bastard ) :) Eric Nelson Technician, West Coast Fiero 310-305-4111
IP: Logged
04:40 AM
GTDude Member
Posts: 9056 From: Keysville, Virginia, USA Registered: Nov 2001
Personally I'd use the 84 model only 4spd getrag 4:10. It's like replacing your rearend and cam. Revs up quickly and in my case the fuel mileage suffered very little. Of course you're turning 5k at 100 or 3k at 60 or 3.5k at 70 and so on........
I had one in my 87GT burgundy and silver that burned......and I loved it. Took off like a bat out of hell.........Good luck.
Phil
------------------ 87 FIERO GT 2.8 5spd 0-60 in 6.8 seconds! 87 FIERO CPE 2.5 5spd 86 FIERO SE 2.5 AUTO 87 FIERO GT 2.8 4SPD If you found my advice helpful, please take the time to give me a positive rating. Thanks
All of the 4 speeds are Muncie transmissions, only the heavy duty 5 speed was a Getrag design. I had a 1984 with the 3.32 transmission, it would be excellent for a V8 conversion, especially a 4.9 Caddy which does not like to rev but makes lots of low end torque, it also may be the strongest transmissiln available. However this tranny has very wide ratios and would not be a happy combination with a cammy engine, like you said, it would drop you out of the power band. As for the 4.10, if you stay off the highway and need strong acceleration this is a good choice, but I would not recommend it to anyone who drives long distances regularly.
Thanks for the info, however most of it doesn't pertain to my situation. I only have access to a 5 speed isuzu or the 4 speed that came with the 1986 V-6.
Personally, I swapped my 4 speed for the isuzu 5 speed. I haven't driven it on the road yet but it's supposed to be better on the highway. The 5th gear lets you go around 70 below 2500 rpm, so mileage and speed should be good on the highway.
There is a lot of debate on this forum about the integrity of the isuzu, since it came off the 4 cylinder cars. Some say it'll take the torque of a V8, some say it won't. My car isn't modded, so if yours isn't I don't think it'll be fine.
The first gear is pretty high, and you'll launch, but you'll have to shift into second really quick, or just start in 2nd.
I had to swap mine, or get the 4 speed rebuilt, so I opted to get a tranny that only had 27000 miles after a rebuild. I got it on ebay. You might want to get the one you're taking from the car checked, or maybe spin through the gears if you can.
Ummmmm, I was always under the impression and fact that the 4speed w/4.10 gear was in fact an Isuzu unit. Can't seem to find the proof at the moment, but.....??
Unless you plan on spending alot of time at highway speeds, or looking for the best gas mileage, go with the 3.65 4 spd from the 86 SE.
You won't be dissapointed with this, it's a great performing transaxle behind the 2.8.
I just converted 2 V6 Fiero's back to the 3.65 4spd's for customers this week, the isuzu in one, and the 3.32 4 spd in the other just wasn't cutting it for them.
------------------ 1988GT T-Tops, 5spd, Loaded
IP: Logged
03:09 AM
Erik Member
Posts: 5625 From: Des Moines, Iowa Registered: Jul 2002
I have a 4.10 Muncie out of a 84 SE in an 88 coupe with a 3.4 DOHC and it will pull the wheels off the ground. There isnt anybody so far Ive encountered that can take me off the line or even at 50. It cruises at about 3200 at 70 in 4 th which might bother some but I think the motor is real happy in that range just starting to come in its power band. There is a rare 5 speed out of a 91 W41 or 91-93 Achevia SCX that has the 3.91 final drive ratio and its a 5 speed getrag. The only problem is that it has a unique bellhousing ( quad 4 2.3) that wont bolt up to a v6 Fiero but you can change the bellhousing so it will fit. It offers the best of both worlds with excellent acceleration off the line and top end with low rpm highway cruising
IP: Logged
03:21 AM
Will Member
Posts: 14275 From: Where you least expect me Registered: Jun 2000
The Isuzu 5 speed as used in Fieros has a pretty tall 3.35 final frive. It will give you approximately the same highway RPM as the 3.32 4 speed. The Isuzu has nicely spaced 2nd, 3rd, 4th, and 5th gears, but the 1-2 drop is huge, as big as the 1-2 drop in the 4 cyl Muncies.
The 3.65 Muncie will offer better acceleration in gear, but more RPM drop on shifts, although it has a tighter 1-2 split than the Isuzu. It will also give higher RPM at highway speed than the Isuzu. 3,000 RPM in top gear is 74 mph with the Muncie and 89 with the Isuzu on stock sized Fiero tires.
