Six-Speed Manual Tremec T56 (MM6/M12) Car Transmission

2004 Model Year Summary

· 6-speed added to new Cadillac CTS-V model late in 2004 model year
· No changes are scheduled for the 2004 model year for Corvette applications

FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES

SIX-SPEED ADDED TO NEW CADILLAC CTS-V MODEL LATE IN 2004 MODEL YEAR
The 6-speed (M12) that was created for the Z06 Corvette for the 2001 model year will be used in a new performance version of the Cadillac CTS beginning late in the 2004 model year. This version of the 6-speed has a higher ratio first gear than the 6-speed (MM6) used in the base model Corvette. The Cadillac will be powered by a version of the Corvette's LS6 V-8.

LOW MAINTENANCE
The 6-speed uses DEXRON III fluid and is certified "fill-for-life," requiring no fluid changes. The clutch is activated hydraulically, which automatically compensates for clutch disc wear, eliminating manual adjustments. The 6-speed was originally designed to require virtually no maintenance.

OVERVIEW
The Tremec T56 evolved as a higher-torque capacity, 6-speed version of the proven M49 5-speed manual transmission, and was introduced in the 1993 Chevrolet Camaro and Pontiac Firebird. It was also added to the all-new 1997 Corvette.

For 2002 model year, the 6-speed received carbon blocker rings on its synchronizers, increasing the durability of the transmission. A new Z06 Corvette model was added for model year 2001, featuring a high output LS6 V-8 engine. To get maximum performance from this model, a variation of the Tremec T56 (the basis for the 6-speed manual) with a higher ratio first gear was used (M12 - see specifications page). This variation of the 6-speed continues to be used on the Z06 model, while the 6-speed with the lower ratio first gear is used on the base Corvette.

Design features include a combination of double-cone and triple-cone synchronizers on all forward gears. Synchronizers act like clutches to speed up or slow down a gear that is being shifted to. Double-cone synchronizers have two friction surfaces to effect this gear acceleration, and triple-cone synchronizers have three friction surfaces. The greater the friction surface, the easier the transmission is to shift. In addition, double-cone and triple-cone synchronizers are smaller in diameter than a single-cone synchronizer with the same friction area allowing the transmission to remain more compact.

Further refinements in design include needle bearings on all forward gearsets and fifth and sixth gear synchronizers located on a countershaft. The countershaft location of the fifth and sixth gear synchronizers allow those gears to be selected without affecting the first through fourth gearsets, contributing to ease of shifting.

Source:
http://media.gm.com/division/powertr...emec%20T56.doc

 

With the torque of the LS6, I wonder why they put a lower 1st gear ratio.

 

Would they be trying to slow it down ... ?

Ted

 

THe CTS-V is going to be so god damn fast. Between the 400HP LS6, this M12 tranny and the 3.73 rear end gears this thing should be faster than the Cobra.

 

I am thinking high 12's..................too bad it doesn't have the weight advantage of the ZO6................but then the Caddy would be as fast as the top dog Vette, and we can't have that.

 

Aerodynamics will make it a bit slower than the Z06 too though, aside from the weight...It might be a nice race between a regular 'Vette and a CTSv

 

I thought this trans had a numerically higher gear ratio in 1st, to give better accel, since you'll have more tq multiplication.(as in, the gear would be shorter) That should help it scoot from a standstill, with the weight and the 18"? rims..


I've always thought 1st gear in the t-56 was always a little tall.


Didn't the new cobra get slgihtly different gearing in their T56 too?

 

I know I know, no magazine racing but MT got a 4.6 0-60 time and a 1/4 mile time of 13.2...

It is plenty fast but the 1/4 mile time needs to be a little better, just under 13 would be perfect... but oh well. it is an awesome machine nonetheless

 

Did that issue just come out? I have not seen it tested anywhere. I think there was a few predictions of what it would run, but nothing with actual instruments........................plus we all know they can't drive anyway.

 

The LS6 may make great peak torque, but I can say that, based on my experience with high-revving motors in big sedans, that the lower 1st gear of the M12 will be much welcomed when combined with 3.73s. 4.10s or 4.56s would be a better match if the CTSv got the standard 1st gear ratio of 2.66:1. I thoroughly applaud this choice and can say that it will make for a much more satisfying driving experience. Probably will help clutch life, too, which might end up being a concern.

The addition of the triple-cone synchros on 1st and 2nd along with the carbon friction material (instead of the crappy organic stuff) on the blocking rings is a notable improvement, but all that stuff listed in the last paragraph is baked into every T56 since they came out. Just seemed like someone was trying to pad their document with that info, that's all.

 

Yes I know they can't drive I guess I should have put that disclaimer on there. It is in print and some people have the issue with them. It is the September issue and they test the new 04 Malibu as well. The article is not online yet i already looked but it should be there soon probably next week, now if only I can get someone that has Speed channel to record the show. Do they still show MT TV on Speed?

 

Of course... Everyone else flaunts info like that.. The fancier it sounds, the better it must be! It just wouldn't fit the image right if people knew the f-bod's had the same tranny too.. heh..

 

But it is a good measurement to how one car stacks up against another, since the constant is the magazine driving method. Also is the fact most all of them average out acceleration times, instead of relying on just a single one or the best one. There's always someone who is going to end up with a quicker times because of different conditions or a "good" engine.

 

Same tranny as the 03 Cobra,It is pretty popular these days with the BIG 3.....

 

Name another tooled-up 6sp transmission that's readily-available to an OEM for $500 or so. It's a short list of, uh, one

I'm interested to see how this thing feels in a CTS. Since the shifter is directly mounted to the trans, it's difficult to filter out vibration, noise, and heat without turning the shifter into mush. I'm also sure that we'll hear plenty of complaint from magazine pukes who don't understand that you can't harness 400 ft-lb of torque without some serious parts, and that those serious parts will require a bit more effort to move around than your average econobox tranny.