Isuzu transmissions suck! - Transmission Forum

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Isuzu transmissions suck!
Sunday, August 22, 2004 3:42 PM
I know this has been posted before.. but I haven't seen it in a while and frankly, it makes interesting reading...

Myth: Isuzu Transmissions Suck Because I Keep Blowing Up Gears In My Cavalier/Sunbird And All The Fiero Guys Claim The Muncies Are Better

The Isuzu 76 mm transmission, as specced out by Isuzu, is all but indestructible when compared to the range of front wheel drive transmissions used in production vehicles. Isuzu hot rodders have had no reported problems running over 450 HP and an equal amount of torque through these transmissions, the most common complaint being that they can not find (or rather refuse to buy) axles that will take this level of power. Lotus used this transmission in their Elan M100 and bought roughly 1 1/2 times more transmissions than engines, anticipating the same failure rate as the Renault transmissions they used in their Esprits, only to find that in the decade following introduction of the Elan M100, they did not experience a single transmission failure in all the Elans they sold, forcing them to sell off several thousand transmissions at under half what they purchased them from Isuzu for. This is much stronger than Mitsubishi, honda, and arguably stronger than anything Muncie/New Venture/Getrag ever built. However, when considering the use of these transmissions by General Motors in 1994-1999 models such as Cavalier and Sunfire/Sunbird, it must be taken into consideration that General Motors changed the metal tempering specifications on both the gear clusters as well as the differentail planetary gears. This was done by General Motors to save money, as the Isuzu specification, as with almost every aspect of Isuzu car building, was far in excess of the capabilities of the vehicles the transmission was to be used in. General Motors reduced the steel tempering so that the transmissions they contracted from Isuzu were built to withstand only the capability of the engines they were using in their vehicles, and GM's specifications were far below Isuzu's own specifications. GM also had the synchros redesigned from a single piece unit to a two piece unit which engages slightly more smoothly but wears out much more quickly. As a result, GM enthusiasts complain loudly about the quality of the Isuzu transmissions, wrongly blaming Isuzu, when they should be blaming General Motors for telling Isuzu to provide GM with transmissions that are not as strong as the transmissions that Isuzu used in their own vehicles.

The solution is for GM enthusiasts to either seek out and use the Japanese spec transmission internals (this will limit the availability of gear ratios, which are typically lower in the Isuzu cars) or to seek supplimental steel tempering for the GM spec transmission internals when they build their transmissions, to bring them up to the tempering specification that Isuzu used in their own cars (through heat treating and/or cryogenic treating).

With specific regard to the Muncie/Getrag/New Venture transmission found in 2000+ Cavaliers and Sunfires, these tranmsissions have been found to be extremely weak compared to the Isuzu 76 mm transmissions even when built to the lower GM specification, and especially when compared to these transmissions when built to Isuzu's specificaition. The Getrag/... uses plastic synchros which wear even more quickly (5,000 miles) than even the two piece GM redesign for the Isuzu transmission. In addition, owners of the 2000+ vehicles with these Getrag/... transmissionshave reported even more transmission failures than did owners of the 94-99 cars with the reduced spec Isuzu transmissions. Clearly GM has decided that they will not be putting any money into building the transmissions of these vehicles any stronger than they must and performance enthusiasts are left to seek additional stress releiving and tempering when building a transmission to match their engine enhancements with the Getrag/... just as they must with the GM reduced spec Isuzu transmissions.

...j

<br>

<a href="http://www.j-body.org/members/jlenko/cars/3/"><img src="http://members.shaw.ca/johnz24/images/zm_sig2.jpg"></a>

Re: Isuzu transmissions suck!
Sunday, August 22, 2004 5:19 PM
Wow, great post. Now all I have to do is find a Japan spec tranny to swap guts with right? I already swapped the guts out once, so now I know I can do it in a day. Of course I'm assuming that all 76mm Izuzu trannies can be swapped out for the guts of another 76mm trans. It's just the integral bellhousing (and gear ratios) that are different right? <br>

<img src=http://ourworld.cs.com/jwithspray/Jbeier_sig2.JPG>
Re: Isuzu transmissions suck!
Sunday, August 22, 2004 5:43 PM
i would also like to know the same? are all 76mm isuzu parts interchangeable?

as far as gear ratios go. they are limited but the 90-93 geo storms(non gsi models) as well as the 90-93 isuzu impulses were available with a 3.83 and a 3.58 fdr which would cater to both 2.2s as well as 2.4s.
plus the ratios for 2-5 are much better than are stock gears. <br>


Don't steal, the government doesn't like competition
Re: Isuzu transmissions suck!
Sunday, August 22, 2004 7:23 PM
2.4
1st 3.73
2nd 2.18
3rd 1.33
4th 0.92
5th 0.74
FDR 3.94

2.2
1st 3.91
2nd 2.18
3rd 1.45
4th 1.03
5th 0.74
FDR 3.58

Impulse/Storm SOHC
1st 3.272
2nd 2.043
3rd 1.448
4th 1.027
5th 0.829
FDR 3.833


I dunno, that 1st gear looks awfully tall campared to the 2.4 trans, plus a numerically lower FD. It might feel like you're starting off in second, lol! <br>

<img src=http://ourworld.cs.com/jwithspray/Jbeier_sig2.JPG>
Re: Isuzu transmissions suck!
Monday, August 23, 2004 9:53 AM
so "Isuzu" should be changed to "GM/Isuzu" i wonder why isuzu would allow their name on such a bunk product. that kinda negative press in the making..

yeah man great post. now im really glad i wont be swapping to the newer trans. these GM/Isuzu trans really do suck though <br>


Sven you totally quarterloafed your computer..
Re: Isuzu transmissions suck!
Monday, August 23, 2004 11:28 AM
interesting read !?!?!?


this explains why GM fawk'd up saturn now !!!



<br>



Re: Isuzu transmissions suck!
Monday, August 23, 2004 6:26 PM
do the nvt 550 getrags from a 94 ho grand am with the internal slave unit bolt to the later 2.4 engines,. and are they stronger.
Re: Isuzu transmissions suck!
Monday, August 23, 2004 6:32 PM
yes and yes. there is a whole big post with good info made by changeforabutton, check it out. <br>


Sven you totally quarterloafed your computer..
Re: Isuzu transmissions suck!
Monday, August 23, 2004 6:37 PM
How exactly did the fawk up saturn? ions and vues are everywhere. Saturns are still selling great. <br>


Read, then process the info, think logically, than if you don't have a headache afterwards, post your response
Re: Isuzu transmissions suck!
Monday, August 23, 2004 7:09 PM
Nice post John!! That explains alot about my tranny woes!!
<br>

Jason
99 Z24
#25 to register on the Org !!
www.newdawncustoms.com
Johnny Mack Turbo Systems
Engineered Performance
Re: Isuzu transmissions suck!
Wednesday, August 25, 2004 7:50 PM
i have to agree with you on some of the info but other info i will not. For one the synchros in the getrag are not plastic and i know that for a fact because i just rebuilt mine. Second if i remember right the shift forks are alot stronger in the getrag than in the isuzu. At least that is what my buddy was telling me that has a 99 cav with the isuzu tranny and he has blown his up 3 times and i have only screwed mine up onca and he has half of the miles on his than what i have on mine. The shift forks are made out of steal but have some plastic tips on the end of them which is what caused my second gear to go out. One of the plastic tips fell off (bad design IMO) which caused it to put my slider ring in a bind and round off the second gear synchro. But $hit happens. Other than that happening i have had no problems what so ever with my tranny. Hell Last year i was putting 217hp and 231ft/lbs to the ground and still did not break a thing including an axle. But i will say i will be pushing the limits even more to see what the getrag can handle. Just built my motor for more boost and should be pushing 300+ hp to the ground. And for the record i do expect to break something but why replace it if it hasn't broke yet and i have the money saved up to replace whatever i does break when it happens. That is just my .02 <br>

If your interested in custom aluminum tilt wheel levers hit me up!

Re: Isuzu transmissions suck!
Thursday, August 26, 2004 12:34 AM
I can vouch for that...... we just blew the 'Geo/Isuzu Machined Spider Gear' Diff up tonight in our Team Green Car....... just doing a burn out in the water box, with Drag Radials...... oh well, time to look for a getrag.

My 02 getrag didnt have the plastic syncrose either, but I think the old school ones might have..... not sure. I do know the shift forks in both the isuzu and new getrag suck.

<br>

SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Isuzu transmissions suck!
Thursday, August 26, 2004 1:30 PM
Quote:


With specific regard to the Muncie/Getrag/New Venture transmission found in 2000+ Cavaliers and Sunfires


As usual, confusion abounds as to what transmissions are considered "Muncies". The 2000+ transaxle is a "Getrag". It was engineered and built by Getrag with the specifications GM provided them.

The 1987-1992 HM282 is referred to as the "Muncie/Getrag". It was engineered by Getrag also, but was built directly by GM in (go figure) their Muncie, Indiana driveline plant.

The 1993-1994 NVG-T550 is essentially the same thing as an HM282, but construction was performed by New Venture Gear, a GM subsidy, and not General Motors. <br>

<img src="http://portfolio.iu.edu/dcletten/Sig.jpg">
Re: Isuzu transmissions suck!
Thursday, August 26, 2004 3:58 PM
funny I just read the information in that first post online this morning.... good stuff...

I also learned that one of the Fieros came with a Isuzu 5spd that has a different first gear and FDR (if I recall) that may work in the Isuzu tranny as well (for us 2.2 guys). I have the info at work. Ill post tomorrow.

Dan <br>


FOR SALE: NEW PHATOM GRIP FOR ISUZU $250 shipped

247HP/267ftlbs at 13psi with built motor

Project updates and stuff: www.clubhousecustoms.com
email: dhc1902@yahoo.com
Re: Isuzu transmissions suck!
Thursday, August 26, 2004 9:34 PM
Quote:

I also learned that one of the Fieros came with a Isuzu 5spd


If the Fiero is a 2.5L I4/5 speed (which were all of them save for '84, '84 used a 4 speed manual) then yes, it is an Isuzu. The transmission itself will not be a direct interchange, but all internals should work fine. <br>

<img src="http://portfolio.iu.edu/dcletten/Sig.jpg">
Re: Isuzu transmissions suck!
Friday, August 27, 2004 5:00 AM
Ya I was thinking about using the final drive from the MT2 Isuzu 5spd. Here are the specs on that tranny...

1st 3.73
2nd 2.04
3rd 1.45
4th 1.03
5th 0.74
FDR 3.35

Then what I really need is a 3.5:1 first gear. That would make it quite useable I think. As it stands now 1st and 2nd gear seem almost useless when your making 250ftlbs at 3500RPM

Anyone know of a 3.5:1 Isuzu gear? First gear from the 2.4 would help but...



Dan

<br>


FOR SALE: NEW PHATOM GRIP FOR ISUZU $250 shipped

247HP/267ftlbs at 13psi with built motor

Project updates and stuff: www.clubhousecustoms.com
email: dhc1902@yahoo.com
Re: Isuzu transmissions suck!
Friday, August 27, 2004 9:07 AM
Impulse/Storm SOHC
1st 3.272
2nd 2.043
3rd 1.448
4th 1.027
5th 0.829
FDR 3.833


The Fiero has the same 1st and 5th as the 2.4, and 3rd and 4th as the 2.2......... almost sounds like the Close Ratio setup right there.
<br>

SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Isuzu transmissions suck!
Friday, August 27, 2004 9:31 AM
Brian,
What failed in your Izuzu trans, the older differential? What tires were you using?

<br>

275hp & 306tq - 1999 2.2 ohv
13.2 @ 108 mph
-1996 2.4 liter + Turbo + Built motor + Torco + More boost = Lots o' Power
-2000 Mustang GT + 2004 Cobra motor, Whipple 2.3 supercharger,
built rear-end,Dodge Viper spec T56 6 speed, bolt-ons = wheelies at the track!!!!!

Re: Isuzu transmissions suck!
Friday, August 27, 2004 10:02 AM
Ya, here is what I am thinking.


1st 3.272 Geo 1st gear
2nd 2.18 2.2 stock
3rd 1.45 2.2 stock
4th 1.03 2.2 stock
5th 0.74 2.2 stock
FD 3.35 Fiero 4cyl final drive

This is how things would look :

<img src="http://clubhousecustoms.com/modules/gallery/albums/album02/modified_gear_ratios.sized.jpg" height=500 width=750>

WIll get me another 8-9 MPH in first....


Dan



<br>


FOR SALE: NEW PHATOM GRIP FOR ISUZU $250 shipped

247HP/267ftlbs at 13psi with built motor

Project updates and stuff: www.clubhousecustoms.com
email: dhc1902@yahoo.com
Re: Isuzu transmissions suck!
Friday, September 10, 2004 2:35 AM
So what im understanding is that the geo gears can be swapped with no problem and that they are stronger than the stock isuzu ones? <br>


<img src=http://registry.gmenthusiast.com/images/1meanz/jordansig.jpg>
2.4 Liters of Asphalt burning Powa!!!
Sponsored by Cavafear Motorsports
Re: Isuzu transmissions suck!
Friday, September 10, 2004 10:13 AM
Has anyone tried to cryotreat the isuzu diff yet???

<br>

Jason
99 Z24
#25 to register on the Org !!
www.newdawncustoms.com
Johnny Mack Turbo Systems
Engineered Performance

Re: Isuzu transmissions suck!
Friday, September 10, 2004 10:25 AM
Adler....... yea, we blew the diff....... worse then the J-body diff.....

BFG Comp T/A Drag Radials........ well broken in.

I'll get some pics of it, and post them up.

<br>

SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Isuzu transmissions suck!
Friday, September 10, 2004 11:01 AM
Were you using your "Team Green" differential blocks with the stiffer springs when the diff fell apart?

<br>

275hp & 306tq - 1999 2.2 ohv
13.2 @ 108 mph
-1996 2.4 liter + Turbo + Built motor + Torco + More boost = Lots o' Power
-2000 Mustang GT + 2004 Cobra motor, Whipple 2.3 supercharger,
built rear-end,Dodge Viper spec T56 6 speed, bolt-ons = wheelies at the track!!!!!

Re: Isuzu transmissions suck!
Sunday, September 12, 2004 12:22 AM
Hey just wondering but is there a way to fit a Muncie/Getrag 284 tranny in our car? Came in early Z34 are a few rare GTP's with the 3.4 DOHC. Its kinda rare but can handle oodles of power.

I dunno if they are just for V6's though. Wouldn't think so since they put a 282 in fiero's and they are V6's so I would think the stronger 284 would fit our cars.

btw my buds 284 is holding just over 300hp now, it outlasted a motor and a half lol. <br>


22 miles per gallon and dropping fast...
Re: Isuzu transmissions suck!
Monday, September 13, 2004 10:04 AM
BTW how hard is it to install the LSD???

<br>


"*PROCRASTINATION* Hard work often pays off in the long run, but laziness always pays off now"
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