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'84 econo 4-speed by Robroyoldboy
Started on: 07-15-2014 03:50 AM
Replies: 13 (173 views)
Last post by: olejoedad on 07-16-2014 10:43 AM
Robroyoldboy
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Report this Post07-15-2014 03:50 AM Click Here to See the Profile for RobroyoldboyClick Here to Email RobroyoldboySend a Private Message to RobroyoldboyEdit/Delete MessageReply w/QuoteDirect Link to This Post
So I'm doing some digging on Wikipedia, and I find the ratios for all the stock manual transmissions (at least I think it's all of them). As someone who plans to make monstrous torque, I begin to wonder about the '84 econo trans, with it's MUCH taller gearing than almost all the others. Does anyone have experience with this trans? Is it strong enough to hold up to 400+ lb/ft? Thanks to you guys I know the case on the '84's didn't have the strengthening ridges, but does that have a significant impact on the strength of the case, so much so that I need to look for a ridged case?

Also, where else might I be able to find one of the econo 4-speeds other than a Fiero? I hope I don't have to worry about that, but it never hurts to have more info.
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E.Furgal
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Report this Post07-15-2014 06:45 AM Click Here to See the Profile for E.FurgalSend a Private Message to E.FurgalEdit/Delete MessageReply w/QuoteDirect Link to This Post
is the gears 1st/2nd/3rd/4th taller or is it the final drive gear that's taller.. I'm thinking the latter...
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tom10122
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Report this Post07-15-2014 08:09 AM Click Here to See the Profile for tom10122Click Here to Email tom10122Send a Private Message to tom10122Edit/Delete MessageReply w/QuoteDirect Link to This Post
That is 3 times more torque then the iron duke keep that in mind.
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Gall757
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Report this Post07-15-2014 08:26 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
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olejoedad
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Report this Post07-15-2014 08:32 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by E.Furgal:

is the gears 1st/2nd/3rd/4th taller or is it the final drive gear that's taller.. I'm thinking the latter...


The econo trans (MY8) has a taller fourth gear and final drive than the other four speed transmissions.

400#/ft is way more torque than any of the four speeds were designed for. Cryogenic treatment and an external cage on the housing would up the power handling capabilities somewhat, but expect to become adept at transmission changes .......
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KillerFrogg
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Report this Post07-15-2014 02:35 PM Click Here to See the Profile for KillerFroggClick Here to Email KillerFroggSend a Private Message to KillerFroggEdit/Delete MessageReply w/QuoteDirect Link to This Post
From what I understand, the MY8 trans is a rare bird, as most '84 cars came with the 4.10 final trans. And if you want a 4speed to deal with power, then go for the 4 speed that came on the v6's in 85/86 they are geared better for the torque, and the cases are webbed more, so can deal with more strength, and compared to a MY8, are probably easier to get ahold of.
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E.Furgal
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Report this Post07-15-2014 02:45 PM Click Here to See the Profile for E.FurgalSend a Private Message to E.FurgalEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by olejoedad:


The econo trans (MY8) has a taller fourth gear and final drive than the other four speed transmissions.

400#/ft is way more torque than any of the four speeds were designed for. Cryogenic treatment and an external cage on the housing would up the power handling capabilities somewhat, but expect to become adept at transmission changes .......


so 4th in this trans is overdrive...
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E.Furgal
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Report this Post07-15-2014 02:48 PM Click Here to See the Profile for E.FurgalSend a Private Message to E.FurgalEdit/Delete MessageReply w/QuoteDirect Link to This Post

E.Furgal

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I'd think this trans 200ft lb would be max if not past spec.. as there was no reason to build them for tons of power..
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Madess
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Report this Post07-15-2014 03:04 PM Click Here to See the Profile for MadessClick Here to Email MadessSend a Private Message to MadessEdit/Delete MessageReply w/QuoteDirect Link to This Post
From my experience the 4 speeds are quite solid, I have raced a 84 4.10 for multiple races, over 100 hrs in 24 hours of lemons with out a problem. Ran a Getrag, blew up 12 hours. Granted I didn't know the history of either transmission, so the Getrag may have been bad from the start. I know the 4 speed had over 100k miles on it.

I have a 4 speed in my built 3.4 with no issues.
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Arns85GT
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Report this Post07-15-2014 03:08 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm running the 3.65 with my Caddy/Carb conversion at 245 ftlbs and 206 hp. (I may increase that but I haven't decided if I can afford to yet)

The transmission is strong and handles this one well, however, freeway work is the rub on this setup. It gets pretty buzzy at 70 mph.

I need a taller 4th for that. The rest of the gears are fine, however, you are going to top out in 3rd at 70 mph under WOT.

I would do the gear change or convert over to the Getrag if I was using it on the freeway allot.

Arn
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Robroyoldboy
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Report this Post07-16-2014 01:45 AM Click Here to See the Profile for RobroyoldboyClick Here to Email RobroyoldboySend a Private Message to RobroyoldboyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by E.Furgal:


so 4th in this trans is overdrive...


According to the Wikipedia article, there was not a manual trans that came in these cars that was NOT overdrive.
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olejoedad
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Report this Post07-16-2014 07:01 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Robroyoldboy:


According to the Wikipedia article, there was not a manual trans that came in these cars that was NOT overdrive.


Correct, all of the four speeds have overdrive fourth gear.

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E.Furgal
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Report this Post07-16-2014 08:38 AM Click Here to See the Profile for E.FurgalSend a Private Message to E.FurgalEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by olejoedad:


Correct, all of the four speeds have overdrive fourth gear.


you happen to have a listing of the different 4 spd and gear % 1st/2nd/3rd/4th..
I'm curous what the o/d % are... I figured that in 84 a 4 spd 4th would be 1 to 1
I know my '84 t/a 4spd was 1 to 1 and the reason for the Optional (extra cost ) 5 speed..
not doubting you.. but why would the general reengineer the car for the 5spd if the 4sp was already o/d.. and getting that past the bean counters..
as dumping a different trans would be costly in parts and in e.p.a. testing
has me wondering.. as I know where a 4spd is and it work good in the idea I have for a casket rod..

[This message has been edited by E.Furgal (edited 07-16-2014).]

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olejoedad
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Report this Post07-16-2014 10:43 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
You should never doubt me......
4 speeds 4th final
1984 MY8 0.73 3.32
M17 0.81 4.10
1985 M19 0.81 3.65

5 speeds 5th final
Isuzu MT2 0.74 3.35
Getrag MG2 0.72 3.61 (4th and 5th are OD)
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