Alright, so I got a deal on an 84 MY8 Econo trans I couldn't pass up. This is the 2.5l 4spd from the 84's that did not have ribs cast into the case.
This transmission will be mated to a 200HP 3.4 pushrod that's been modified a bit. It will not be drag raced or run at a track, but it will be driven like a sports car should be. I know how to drive a manual and do not make hard shifts.
Will this transmission hold up to the engine okay with the stock case? I have heard the case is fairly weak, but I do not relish the idea of merging 2 transmissions together.
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86 GT with C&C T-Tops - 4.9l V8
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02:18 PM
PFF
System Bot
Old Lar Member
Posts: 13798 From: Palm Bay, Florida Registered: Nov 1999
The econo transmissions are rare as hens teeth. You may want to find a HD transmission and trade the econ one to someone that wants to make a economy Fiero.
From what I understand, the Econo 4spds are the most valuable Fiero transmission there is...trading one for a Getrag might be nice. I'll post a trade offer in the mall.
Most people end up using the Fiero V 6 4 speed that had the 365 gears and putting the econo parts into that case for the extra strength as the 84 case is very weak. Dan
Alright, so I got a deal on an 84 MY8 Econo trans I couldn't pass up.
What kind of deal did you get? I have been on the hunt for one of these for a long time and finally bought a nearly complete car soley for the transmission. You can PM me if you don't want to state it here.
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Originally posted by MadDanceSkillz:
From what I understand, the Econo 4spds are the most valuable Fiero transmission there is...trading one for a Getrag might be nice. I'll post a trade offer in the mall.
I don't know about them being the most valuable Fiero transmission but you might be successful with your trade request.
I am going to be trying to make a hybrid trans with my econo and a V6 4-spd this winter. If you end up not using or trading yours let me know and I might take it off your hands if the price is right.
I don't have a problem saying what I got it for. 250 bucks. Took a hell of a long time calling every damn parts dealer in the eastern part of the nation, though. haha
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10:22 PM
Dec 22nd, 2009
Will Member
Posts: 14300 From: Where you least expect me Registered: Jun 2000
Alright, so I got a deal on an 84 MY8 Econo trans I couldn't pass up. This is the 2.5l 4spd from the 84's that did not have ribs cast into the case.
This transmission will be mated to a 200HP 3.4 pushrod that's been modified a bit. It will not be drag raced or run at a track, but it will be driven like a sports car should be. I know how to drive a manual and do not make hard shifts.
Will this transmission hold up to the engine okay with the stock case? I have heard the case is fairly weak, but I do not relish the idea of merging 2 transmissions together.
Don't abuse it. In your shoes, I'd built a hybrid Muncie as outlined in your other thread. The Muncie is dirt simple inside and very easy to work on.
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02:48 AM
jscott1 Member
Posts: 21676 From: Houston, TX , USA Registered: Dec 2001
Pontiac discovered first hand when they were building the Indy Pace Car that the 84 transmission can't hold that much power. First time on the track the transmission split in half. I heard that right out of the mouth of John Callies, the driver of the pace car.
I don't have a problem saying what I got it for. 250 bucks. Took a hell of a long time calling every damn parts dealer in the eastern part of the nation, though. haha
Good deal. I paid $350 for my parts car and so far have gotten back $29.60 in scrap and a HUGE pile of change that I haven't counted yet. I did have a tow dolly rental and the cost of gas to factor into it as well which make my costs a little higher. I hope to be able to sell off a little bit of stuff off the car and get the costs down a little closer to what you paid.
Some people have been marking up the transmissions themselves to $450 but there is no hard evidence that they actually sell for that and IMO that price point makes the investment nearly impossible to recover.
I have the tools to set the bearing preload on these transmissions. I am going to try and make my hybrid over the winter. If you can wait till spring I could help you do yours as well. I have been inside a few transmissions and the muncie is indeed as simple as they get.
As far as price goes, these transmissions seem to be hit and miss. I have seen them sell for 700 and 825 on two occasions, while at other times they sell between 200 and 500 dollars. If I were to sell mine outright, having low miles, I'd probably ask 600 for it. I sold a regular 3.65 4spd with similar miles for 300 dollars and those are very, very common.
Just a heads up, they're a little tougher than people are suggesting. My old '84 had the MY8, I mated it to a Series I 3800 and the trans never missed a beat. Held the power fine. With aggressive driving I could see it grenading though, and given you're in the States not on the other side of the planet where GM FWDs are nowhere to be found, I'd look for a less explodable example
On a 200 hp engine I would not use the Econo gearbox for 2 reasons. The first one is the gear ratios. They were meant to help a 90 hp engine get up its revs to working speed. They were not intended for the grunt of a v6. You just will find first gear to be all but useless.
The second reason is that the tranny was designed for a 90 hp engine. The 365 tranny was designed for a 140 hp engine. It just makes good sense to give the 200hp engine the best tranny for the power and rpm range. The 365 is arguably the toughest Fiero Tranny and the best performer on the quarter mile.
I would sell your Econo tranny and buy another one. Just my .02
JeffreySuko is going to hybridize it with a 3.65 using the 3.65 1-2 gears and the MY8 3-4 gears and final drive gear. This should make the perfect transmission for me...4 speed fun, better than 5spd gas mileage.
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02:03 PM
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
Originally posted by FIEROFLYER: Most people end up using the Fiero V 6 4 speed that had the 365 gears and putting the econo parts into that case for the extra strength as the 84 case is very weak. Dan
yup. this is the answer
yes - the 4-cyl case WILL break.
the guts are interchangeable to do properly, tho, you do need a special tool to shim the bearings
I actually had this trans on my old 3.4 and it cracked the case after 6 months of driving. I didn't beat on the car, but did drive it. I remember leaving my friends house and when I shifted into second I heard a loud clunk, then a howling type noise. I looked in my review mirror and say a trail of trans fluid following me
Alright, so I got a deal on an 84 MY8 Econo trans I couldn't pass up. This is the 2.5l 4spd from the 84's that did not have ribs cast into the case.
This transmission will be mated to a 200HP 3.4 pushrod that's been modified a bit. It will not be drag raced or run at a track, but it will be driven like a sports car should be. I know how to drive a manual and do not make hard shifts.
Will this transmission hold up to the engine okay with the stock case? I have heard the case is fairly weak, but I do not relish the idea of merging 2 transmissions together.
Yes it should hold up fine. I've been thrashing mine for about 5 yrs with a modded 3.4 dohc pushing 300 hp with no problems. Just dont get too sticky of a tire if drag racing
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01:12 AM
Dec 28th, 2009
Carcenomy Member
Posts: 1109 From: Invercargill, New Zealand Registered: Jan 2009
Turns out the transmission we have to work with is most likely from a Citation. That means this transmission does not have the .73 4th gear ratio like the Fiero Econo transmission. We can still use the 3.32 final drive and get an ~9% reduction in crusing RPM when compared to the 3.65 V6 transmission.
The Fiero Econo however would have yielded an ~18% reduction in crusing RPM.
Yeah, I opened the thing up and got 2.7 turns in 4th. I was pretty pissed since the junkyard told me it was 11 1/2 in reverse and 2.4 in 4th.
------------------ 86GT Modded 3.4l Pushrod V6 with Trueleo
PM Me if you need: Lebaron Brake Swap Brackets 38004.9l Motor/Transmission Mounts Fiero Rotor Hubs for Brake Swaps Or any other custom fabricated parts! My prices are very low.
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01:07 AM
Will Member
Posts: 14300 From: Where you least expect me Registered: Jun 2000
Yeah, I opened the thing up and got 2.7 turns in 4th. I was pretty pissed since the junkyard told me it was 11 1/2 in reverse and 2.4 in 4th.
I would *NEVER* trust a junk yard to identify the gear ratio in a transmission. When I call junk yards, I feel lucky if I get a guy on the phone who can count to 11 1/2.
If it's still worth it to you, Jeff, I'd like to have the FD swapped in. Like I was telling you, I have trouble hooking up sometimes in 1st gear because of the engine's power. Like I told you on the phone, I will do my best to make it worth your while with all the parts I have, or some cash.
No problem. I just wanted to make sure you had all the info on what this would do to your cruising RPM such that you could make an informed decision. I will probably tear into it tomorrow.
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06:51 PM
Jan 1st, 2010
Will Member
Posts: 14300 From: Where you least expect me Registered: Jun 2000
According to your spreadsheet, there's ~100 RPM difference in cruising engine speeds... I'd call that pretty much in the realm...
Yeah, I suppose that was a bad choice of words there. I guess my realm was small when I typed that. In all honesty I have been so focused on the Fiero Econo trans that I have probably been to critical of the other options.
Unfortunately it is a moot point as this junkyard transmission has seen better days. It had residual ATF fluid in it which isn't a problem in itself but the fluid had been drained and it sat without fluid in it for quite some time and some moisture found it's way inside the case. Both the diff gear and the output shaft have some rust and pitting on them and I don't feel comfortable using them as there will be reduced life as result. I took pictures and will post them here later tonight.
For anyone reading this, could the ATF be partially to blame for the corossion on these components? How does the oil film of ATF compare to 5W30 motor oil or syncromesh? Just curious for MDS such that he can possibly use the info to get his money back on the transmission.
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04:55 PM
Jan 2nd, 2010
stickpony Member
Posts: 1187 From: Pompano Beach, FL Registered: Jan 2008
Yeah, I opened the thing up and got 2.7 turns in 4th. I was pretty pissed since the junkyard told me it was 11 1/2 in reverse and 2.4 in 4th.
yeah, that sounds like the 4 cyl citation gearbox ratios
does it have the FWD shift levers or the fiero? are the fiero shift cable mounts on it or just the FWD vehicle ones?
the surefire way to identify it would be the sticker thats on it( if there is one ). it will be a series on numbers and letters, and "NA" or "DJ" will be in the part number printed on the sticker if it is a fiero econobox
that sucks bro, sorry about your luck.. keep pressing though, you'll find an econo tranny before long.
Ok, First off. I think this transmission is from a Citation because it has a cable drive for the speedo and a dipstick to check the fluid level. For some reason I did not take a picture of the speedo drive but here is the dipstick. The first indication of what I would find inside this transmission presented itself when I pulled the dipstick out of curosity. After I wrote my last post I noticed that the dipstick calls out Dextron II fluid. This is what I found when I opened the case. The white milky fluid is moisture. Also note the magnet in the upper right corner of the picture is covered in metal debris. This was supposed to be a low mileage unit but the amount of debris tells a different story. This is the component which had the most corrosion. This is the Diff Gear. The dark spots are pitted. Other side of the same teeth. Then this is the output shaft again the dark spots are pitting. Also notice the teeth look like they are polished in the center. This is wear and another indication that this was not a low mileage unit. So after finding this I put it all back together in case MDS needs it to get his money back from the junkyard.
I also opened up my 3.65 unit and this is how one of these transmissions is supposed to look like inside.
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12:44 AM
Will Member
Posts: 14300 From: Where you least expect me Registered: Jun 2000
Originally posted by Jefrysuko: Then this is the output shaft again the dark spots are pitting. Also notice the teeth look like they are polished in the center. This is wear and another indication that this was not a low mileage unit. So after finding this I put it all back together in case MDS needs it to get his money back from the junkyard.
Have you tried cleaning it up with emory paper? It might surprise you... IE, you can stll see the machine marks on the tips of the teeth. That gunk should just polish out. That doesn't look like bad wear on those teeth at all. What does the wear look like on your 3.65 final?
[This message has been edited by Will (edited 01-02-2010).]
Have you tried cleaning it up with emory paper? It might surprise you... IE, you can stll see the machine marks on the tips of the teeth. That gunk should just polish out. That doesn't look like bad wear on those teeth at all. What does the wear look like on your 3.65 final?
Yes I agree the wear does not look that bad but this was supposed to be a 40k mile unit and the wear patterns indicate otherwise. What concerned me was the pitting which was hard to capture in the photos. We did clean it up a little which is what revealed the pitting and the more we cleaned the more we found.
The wear on the 3.65 unit was almost unnoticable. There was no polishing on the surface of the teeth. IIRC it was supposed to be a 70-80K mile unit. It appeared to have had motor oil in it as well which is what I expected from a Fiero Unit.
I brought up to Jeff on the phone that although the car showed 42k miles, if the transmission in the car had a cable driven speedo, it could have had 200k on it for all we know plus what was on the transmission when it was installed. I'm starting to hate transmissions.
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12:12 PM
Jan 3rd, 2010
outlawfiero17 Member
Posts: 1450 From: sacramento, CA Registered: Jul 2009
how can you tell what tans you have? i have an 86 se 4spd. the rpo sticker is long gone. i had it out a while back and lost it. any info helps as im curious
how can you tell what tans you have? i have an 86 se 4spd. the rpo sticker is long gone. i had it out a while back and lost it. any info helps as im curious
All 85-86 4-speeds are the M17 version with a 3.65 FD ratio. That version has more ribs to the case which make it easily identifiable as well.
If you want to verify gear ratios look at my spreadsheet under the "Overall Gearbox Ratio" columns. The number listed is the amount of turns of the input shaft are required for one rotation of the Diff. When MDS did this exercise with his transmission in 4th gear he got approximately 2.7 turns and not the 2.42 turns he was expecting which told him he did not have the MY8 version.
You can see a couple extra ribs that are not present on the Citation version. It isn't anywhere near as ribbed as the Fiero V6 version, but different nonetheless.
