98hardtopSS

Anyone know the difference? I have an oppurtunity to get one cheap and I heard there were improvements for the GTO trans. Ratios different?

Anybody know if they are improved and what it takes to drop one in an fbody?

Thanks
Chris

98hardtopSS

Sorry, its a 6spd. Im sure you knew that though

nhra_crazy

iTrader: (86)

Talk to Demonicbird00 If I remember correctly he has one in his car and there was some gains with it..

C5kid

iTrader: (12)

GTO & Y-body trans have triple blocker rings and a few upgrades. just means a more expensive rebuild also

DannoWS6

iTrader: (5)

The MM6/M12 specs are here
http://www.cadillacfaq.com/faq/answers/pdf/t56-06.pdf

Yeah its an upgrade, but unless your T56 needs an overhaul I probably wouldn't go though the effort, but if your getting a smoking deal it might be worth it. Don rebuilt many a T56 as well, just an FYI.

The M12 is arguably the best t56 you can get. Here are the ratios btw
Your T56 2.66:1 1.78:1 1.30:1 1.00:1 0.74:1 0.50:1
GTO M12 2.97:1 2.07:1 1.43:1 1.00:1 0.84:1 0.57:1

1nicez28

iTrader: (7)

GTO"s t56 bolt right up to an LS1? my buddy is looking for a t56. This might expand his options.

DannoWS6

iTrader: (5)

I tihnk so, think you just need some type of shifter cup adapter.
PewterScreaminMachine had one in his last car. I'm sure he'll chime in.

98hardtopSS

Great info Dan. Thanks.

Keep the feedback coming. I am considering this swap. A GTO just came in and I was given dibs on the trans. All years the same?

DannoWS6

iTrader: (5)

I believe 04+ is the same. Basically the same tranny from the C5 z06. The only stronger factory piece from the era is the spec'ed one for the viper.

If your getting a good deal it would be worth picking up. One in great shape is probably worth a good $1500 to a guy looking for a tranny.

98hardtopSS

You could say it is a good deal. lol. Its damn near stolen

DannoWS6

iTrader: (5)

Makes me wanna do a 6sp swap...almost

Demonicbird00

iTrader: (17)

i had it in my ta for 2 years w/ 4.10s i loved it but needed something alittle more beefier.

w/ 26" tires i would run through the gears fast and shift into 4th a tick before the 1/8 and 4th would take me through the traps at 6800 so nice!!

yes you will need the little shifter cup thing from a fbody, i have nothing bad to say about the mn12 in a fbody

-brandon

1nicez28

iTrader: (7)

how would it be in a LS1 powered fox body with 4.10's? guess i could tell my buddy about this.

itsslow98

iTrader: (18)

Same tranny thats in the first gen V's as well. I can see with 4.10s or such being very short gears.

Might be a bit much in the fox.

Demonicbird00

iTrader: (17)

in a fox would stay w/ a fbody gearing

98hardtopSS

Can I use the shifter cup on my trans already?

DannoWS6

iTrader: (5)

LOL I guess the automatic guy will help you out again

Yeah just swap the one from your current t56



M12 comes with the big one, just swap in your smaller one.


BTW what gears do you have? If you got like 4.10's, just be prepared to get a good right arm workout.

BoostedLT5

iTrader: (1)

Just went the other way and put a faceplated t56 from an f body into my gto. All i swapped were the shifter cups. The car gets better gas mileage now, in 6th at 80 i am at like 1700 rpm's, i need to add some gear!

98hardtopSS

Stock gears. Probably will go with 3:73s if I got this trans.

Thanks for all the help everyone. Sounds like a good deal to me!

NHRATA01

iTrader: (10)

Out of curiosity, does the GTO T56 have provisions for the torque arm mount, or would you have to swap tailshafts with an FBody T56 (or alternatively go with a chasis mount)?