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Unforgiven 11-19-2008 02:15 PM

GM trans swap, lack of info
 
Well having been trying to look into things, and getting interrupted a lot here at home, I will see if someone can add a little info into this topic for me. According to some base info I have gotten, the new 6 speed auto found in the Saturn Aura may be a GM transmission at heart. Now my interest is will this transmission, the 6T70 or 6T75 be a possible replacement for the 4T65E in my vehicle? Have not found links or enough info yet to compare properly. Good hunting and thanks for any comments on this. :thumbup:

cfg83 11-19-2008 04:03 PM

Unforgiven -

It would make sense that the Aura is mostly parted from GM drivetrains, the S-Series was the only "Saturn Unique" drivetrain. Don't know if it will help, but I found this on saturnfans :

Aura on HP Tuners supported vehicles list - SaturnFans Forums
Quote:

Acording to GM's site:
http://www.gm.com/company/gmability/...ns_051806.html

SPECIFICATIONS: HYDRA-MATIC 6T70 / 6T75
Aura 6T70 / Outlook 6T75
Maximum engine torque:
280 lb-ft (380 Nm) / 301 lb-ft (406 Nm)
Final drive ratio:
2.77 / 3.16:1
Maximum validated gross vehicle weight:
4850 lbs / 6384 lbs
Maximum shift speed:
1-2: 6800 rpm / 1-2: 6800 rpm
2-3: 6800 rpm / 2-3: 6800 rpm
3-4: 6800 rpm / 3-4: 6800 rpm
Final drive ratio:
2.77 / 3.16:1
Fluid type:
DEXRONŽ VI / DEXRONŽ VI

I think the Aura could likely gain another 28 lb-ft of torque from 252 stock to 280 with the following upgrades:
Cold Air Intake: 3-4 lb-ft
Cat-Back Exhaust: 8-10 lb-ft
Dyno Tune on 91 Octane: 12-14 lb-ft
Total gain 23-28 lb-ft

Too bad GM didn't put the 6T75 in the Aura but with a 6th gear ratio of 0.63:1 like the Tremec T-56 6-speed manual. It would have given better acceleration the first 5 gears and the same highway mileage in 6th.
CarloSW2

Unforgiven 11-20-2008 10:32 AM

CFG83,
Nice! Thanks for the info, I am digging for all I can find to help me determine if this is something worth chasing after... errr, obtaining <looks around for the sirens again>
Whew, no speeding ticket that time...<grins>

Oooo...<digs on links a bit harder> Nice... <copies and pastes>

New 6T70 and 6T75 FWD transmissions

The new Hydra-Matic 6T70 and 6T75 six-speed automatics are advanced transmissions with clutch-to-clutch shift operation for front- and all-wheel drive vehicles. The transmissions are based on a common design, with the 6T75 rated for higher torque capacity. The 6T70 debuts on the Saturn Aura and on a Pontiac G6 model; the 6T75 will be offered on the Saturn Outlook

The 6T70/75’s clutch-to-clutch operation and 6.04:1 overall ratio help the transmission deliver both performance and fuel economy, enabling up to 7 percent improved performance and up to 4 percent improved fuel economy when compared with current front-wheel drive four-speed automatics. Both transmissions use a very high numerical 4.48:1 first gear, which helps deliver exceptional launch feel, and a 0.74:1 overdrive sixth gear, which reduces engine rpms at high speeds, thereby reducing engine noise and vibrations. Fifth gear is 1:1 direct drive.

With its wide ratio and strong capacity, the 6T70/75 has the capability to transfer more torque to the drive wheels, particularly in all-wheel drive applications. It also helps vehicles, such as crossovers like the Outlook, to feel even livelier at lower speeds, particularly at launch or when pulling away from a stoplight.

The 6T70/75 offers the capability of driver shift control (DSC), which allows the driver to use tap-up/tap-down shifting to select the desired gear for specific road conditions, such as driving up a steep hill. A sophisticated transmission electro-hydraulic control module (TEHCM) is mounted inside the 6T70 and 6T75, reducing vehicle complexity. Similar to the control system used in the six-speed Hydra-Matic rear-wheel drive transmissions, the TEHCM offers improved quality through its hard-wired connections. The unit is located entirely within the transmission and operates while bathed in transmission fluid. Locating the controller internally facilitates the modular design and assembly strategy while also shielding the unit from the outside environment.

The 6T70/75 was co-developed with Ford Motor Co. Co-development of the transmission allowed it to reach production in less time and enabled each company to reduce development costs by as much as 50 percent. A common on-axis design and many common components are shared between GM and Ford Motor Co. The controls, calibrations and operation of the transmissions are unique to each company.

<ends copy and paste>

Looks like an older article, but its more info...muhahahhaaa

Intrigued 11-21-2008 12:00 AM

Hey Unforgiven! I followed your link over.

Whew! Tranny swap stuff nowadays is gonna be tougher than back when we put the 4-speed and Chevelle posi rearend in the '74 Camaro I had. (That was a trip...different types of rearend...pivot already there for the pedal, though...) The Muncie outlasted two rearends, by the way... :rolleyes:

We had two auto tranny specialists at the dealership, so I didn't do much more than service them. It would seem to me that finding out if the thing would fit in the car would be the easier part: controlling shifts would be the hard part. On my car the computer decides yes/no on overdrive and convertor lockup both, and they're solenoid activated, if they're like the older ones. I fear that an auto tranny with more speeds would have to use some kind of manual mechanism for the shifting duties, and might not be worth the work. Just personally, I'd rather try to find a stock tranny with taller gears (my car has the taller gears), and go with slimmer but taller tires. A couple of inches of tire size will help a lot, you'll have less mass with fewer gears in the tranny (I'm supposing...) and you can put a gear with one or two less teeth on the vehicle speed sensor to keep speed accurate.

Just my thinking, mind you! :thumbup:

cfg83 11-21-2008 12:46 AM

Unforgiven -

I had no idea about the joint venture with Ford. I don't think this will add to your knowledge, but I googled "ford transmission 6T70/75 gear ratios" and found some more URLs to read :

GM to Incorporate Innovative Transmission in 2007
GM plans to offer more 6-speed trannies than any other - AutoSpies Auto News
GM-Ford 6-speed automatic transmission - Wikipedia, the free encyclopedia
Code:

Gear ratios:
1      2      3      4      5      6      R      Final drive
4.484  2.872  1.842  1.414  1.000  0.742  2.88  2.77, 3.16, 3.39

The Aura *appears* to be setup for the tallest geared configuration.

CarloSW2

almightybmw 11-21-2008 09:08 AM

just a quick look at the aura, and I'm going to say the transmission will not bolt straight up. GM did bad things with certain engine lines, like the one in your '04 impala. I'm assuming you have the 3.8? yeah, you'd think the older, lesser 3.4 or 3.1 would utilize a similar block, but it doesn't. All 3 use different transmissions (although I think the 3.4 and 3.1 can interchange).

Always wondered why they were floundering, now I know.....

Unforgiven 11-21-2008 11:01 AM

Yeah, sadly the initial look at the two transmissions side by side (4t65e vs 6t70/75) show a bolt pattern difference (which should be adaptable with the right plate and extention for the input shaft) but the mounts, size and many other differences would make this a difficult at best swap. Still have to research things more and get physical dimensions and such to make the final decision. Supposedly the 4t65e I have has a 4th gear ratio of .70 while I see CFG83 found info suggesting a 6th gear ratio of .742... which would actually increase my engine rpm in that gear...hmmmm. LOL pros and cons...
Had not found a 4th gear swap for my trans yet, although I would hope one is available. Did find a link in lazy browsing yesterday that showed some performance transmissions of my type... ah well.
Thanks once again for the info you folks are helping me find!!

Unforgiven 11-21-2008 11:10 AM

Quote:

Originally Posted by almightybmw (Post 73769)
just a quick look at the aura, and I'm going to say the transmission will not bolt straight up. GM did bad things with certain engine lines, like the one in your '04 impala. I'm assuming you have the 3.8? yeah, you'd think the older, lesser 3.4 or 3.1 would utilize a similar block, but it doesn't. All 3 use different transmissions (although I think the 3.4 and 3.1 can interchange).

Always wondered why they were floundering, now I know.....


Heh, GM did many bad things, and quite a few good things. I did not get the 3.8 since I knew it was a lot thirstier than the 3.4, as well as not having had good luck with a 3.8 in a prior vehicle. Sadly, all the big 3 are floundering, and all due to union mismanagement and plain and simple greed in the direct management practices (3 private jets to DC ring a recent bell????)

MadisonMPG 11-28-2008 01:15 PM

Quote:

Originally Posted by Unforgiven (Post 73801)
Heh, GM did many bad things, and quite a few good things. I did not get the 3.8 since I knew it was a lot thirstier than the 3.4, as well as not having had good luck with a 3.8 in a prior vehicle. Sadly, all the big 3 are floundering, and all due to union mismanagement and plain and simple greed in the direct management practices (3 private jets to DC ring a recent bell????)

I get 28 easy in my 3.8 impala, it's fully loaded couple hundred pounds more than the base model.

Unforgiven 12-06-2008 07:53 PM

I hear you there Madison, my unofficial best before I came to this site and really started keeping track of the numbers was a touch over 37mpg, breaking 600miles per tank but filled at 586 miles. Sadly I am having such trouble in convincing the other driver to keep track of the driving that I cannot keep the numbers accurate. Until I get to have more time at home, I doubt I will post any more fuel numbers.


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