: STS Transmissions



EChas3
07-15-09, 01:09 AM
My 2006 AWD 1SG has the '5-speed' transmission. The shifter has 3 forward driving positions: "D", "4" and the 'Sport Mode' through the shifter gate to the right. This provides manual gear selection and/or what the manual describes as: "sport mode, the transmission may remain in a gear longer than it would in normal driving mode based on braking, throttle input and vehicle lateral acceleration."

I have NOT have the ECM/TCM programming updated in my car because I like the positive feel provided by the designers. My wife's 2007 1SE (with the '6-speed' transmission) likely already had an updated shift algorithm from the factory and seems to coast forever. I am sure my car's mpg suffers, but if I cared more about mileage than performance, I'd be driving an econobox.

For those who are not familiar with modern automatic transmissions, they achieve near manual transmission mileage by releasing the torque converter for coasting and using a 'lock-up' when at sufficient speed. This gives a traditional automatic transmission (with only hydraulic fluid providing the driving force) the abilty to coast or act as a locked unit, directly driving the wheels. While 'lock-up' is generally referred to as another gear, technically it is not. However, it does eliminate all slippage and improves both mileage and pulling power.

Sometimes a lock-up torque converter is called Overdrive, but it isn't that either. Overdrive is an even steeper gear than 1 to 1 that turns the drive shaft faster than the crankshaft. While the top gear in the 6-speed (5th gear) may be an overdrive, 'lock-up' (6th 'gear') is a different animal.

In the "4" setting of my STS '5-speed' transmission works just like in "D" but the torque converter never 'locks-up'. It just shifts through the four real gears and because of the programming, it still will slow based on engine speed (like compression braking in lower gears).

'Sport Mode' works like "D" except that shift points are 500-750 RPM higher and the transmission holds a gear even longer than "D" when lifting off the accelerator. I haven't 'thrown it around the bends' enough to know if it really mimics the way I shift my TR6, but I'm looking forward to finding out!

My wife's 2007 does not seem to have a way to defeat the 'lock-up'. As described above, her "D" is behaves more like any other American automatic. 'Sport Mode' works as described and does an adequate job in moderate conditions. For best performance, manual shifting can provide as good performance as the driver can muster.

[To critics, yes, I contend that 2005, 2006 & some later AWD's actually have 4-speed transmissions and the rest actually are 5-speeds. Torque converter lockup is not a different gear. So sue GM. Prove me wrong! Stand in line! Set me straight!]

What settings do you others have in your cars?:want:

What do you like or dislike about the STS transmission?:tisk:

How full of beans am I this time?:stirpot:

K STS
07-15-09, 09:20 AM
great post as usual, EChas. I also note the same thing as you mention here, however I can say the the downshifts while braking, even in sport mode, are MUCH less aggressive than my CTS was. It seemed if I was coasting to a stop, and lightly applying the brakes in my CTS the trans would literally downshift to assist very harshly.

Also, silver02ws6 or whatever says that for the best performance, leave the car in "4" (not Sport mode) and take off. Ive tried it in both, but haven't came to a conclusion if this is actually better. However, he has run a 13.56 with only a corsa and K&N!

next2pool
07-15-09, 12:34 PM
The STS since 2005 has used 4 different but related transmissions: the
5L40E on early V6, the 5L50E on early 4.6, and the 6L80E on all V's. Then the 4.6 went to a 6L50E, and the V6 later also went to the 6L50E when it got direct injection. The first digit indicates actual number of gear ratios, the L means longitudinal, the next number means size and capacity of the gearset, and the E means electronic. In all models 5 and above were overdrive. AWD or RWD had no bearing on transmission model used. All models used a pulsewidth modulated torque converter that can be programmed to be anywere between full unlocked to fully locked and anywere inbetween. That is controlled by the powertrain control module and calibration varies by model year and service updates. The bottom line is that the gear ratios are real and the torque convertor clutch will interact with all gears 3 and above. The trans has the capability to lock the convertor to protect itself in case it gets hot. The shift lever position will allow the driver to select a gear and calibration within limits. The transmission will always override the selection in order to protect the engine or transmission.

WillySTS
07-15-09, 01:23 PM
My 2006 AWD 1SG has the '5-speed' transmission. The shifter has 3 forward driving positions: "D", "4" and the 'Sport Mode' through the shifter gate to the right. This provides manual gear selection and/or what the manual describes as: "sport mode, the transmission may remain in a gear longer than it would in normal driving mode based on braking, throttle input and vehicle lateral acceleration."






'Sport Mode' works like "D" except that shift points are 500-750 RPM higher and the transmission holds a gear even longer than "D" when lifting off the accelerator. I haven't 'thrown it around the bends' enough to know if it really mimics the way I shift my TR6, but I'm looking forward to finding out!

For best performance, manual shifting can provide as good performance as the driver can muster.

[To critics, ... Torque converter lockup is not a different gear. So sue GM. Prove me wrong! Stand in line! Set me straight!]

What settings do you others have in your cars?:want:

What do you like or dislike about the STS transmission?:tisk:

How full of beans am I this time?:stirpot:

I know this is a regular STS forum and not the V section, so don't throw me out for that...:duck:

My car is a 6 speed auto and has only "D" and "Sport" mode. In "S" when cornering hard enough it does downshift and hold in gear while exiting the corner, not quite like I would since, I have owned stick shift cars, I do know how to "heel and toe", but, it beats a poke in the eye with a sharp stick...it's better than nothing. I'm told the CTS V2 "blips the throttle" on downshifts when driving in the sport mode...now, that...is a proper sport shift mode.

"D" is normal Drive and, even though the torque converter"lock" does not disengage at freeway speeds until you apply the brake, it will, however, exceed 90 mph, foot off the gas going down the grapevine(4% grade), even in "S"...6th gear is that tall.

All in all, I like the idea of a 6 speed, having a 1st gear that is near useless in a V(should be a little taller) and then very tall on the top end for good cruising.

EChas3
07-15-09, 11:49 PM
The bottom line is that the gear ratios are real and the torque convertor clutch will interact with all gears 3 and above.

So, if we all have one of the following, how do we know?

5L40E - Early V-6 (All non-DI?)
5L50E - Early V-8 (All non-6-speed?)
6L50E - 6-Speed (Regardless of Engine?)
6L80E - All Automatic V's?


It seems so logical! Would all shifters without a "4" be 6-speeds?

:worship:


(If this is accurate, it is possible to induce my wife's 6L50E torque converter clutch into pulsing when compression braking in third on a steep grade. I have yet to feel this with my 5L50E.)

carter's_sts
07-16-09, 12:06 AM
How do you figure out which trans your car has?

next2pool
07-16-09, 12:23 AM
I'll look it up in the morning and give you some links, but is all about year and engine. There were no variations within a year. Off the top of my head it was: 2005 4.6 >5L50E, 2006 and up 4.6 >6L50E, 2005-7 3.6>5L40E, 2007 and up 3.6>6L50E, 2005 and up 4.4 (STS V) > 6L80E.

I may be off a year on the V6 but tomorrow I'll clarify it.

As a matter of interest, all of these transmissions are variations of the old Chevette THM 180 built in Strassburg--hard to believe that old baby could be made to handle the torque we now have. BMW has used these various versions of the THM for years--they really don't get much better than these.

carter's_sts
07-16-09, 01:09 AM
Cool. Thanks for the info. I was wondering also if there is a label somewhere on the car that would tell you, but maybe not.

dkozloski
07-16-09, 01:19 AM
I'll look it up in the morning and give you some links, but is all about year and engine. There were no variations within a year. Off the top of my head it was: 2005 4.6 >5L50E, 2006 and up 4.6 >6L50E, 2005-7 3.6>5L40E, 2007 and up 3.6>6L50E, 2005 and up 4.4 (STS V) > 6L80E.

I may be off a year on the V6 but tomorrow I'll clarify it.

As a matter of interest, all of these transmissions are variations of the old Chevette THM 180 built in Strassburg--hard to believe that old baby could be made to handle the torque we now have. BMW has used these various versions of the THM for years--they really don't get much better than these.
I think you need to do some more research. My 2006 AWD V8 has a five speed. I've never heard of a 2006 AWD V8 with a six speed and I've seen somewhere that it was not offered with AWD. The 2006 RWD V8 has a six speed.

dkozloski
07-16-09, 01:22 AM
Cool. Thanks for the info. I was wondering also if there is a label somewhere on the car that would tell you, but maybe not.
There is a tag on the bottom of the spare tire cover in the trunk that lists all the options on your car.

next2pool
07-16-09, 10:19 AM
I think you need to do some more research. My 2006 AWD V8 has a five speed. I've never heard of a 2006 AWD V8 with a six speed and I've seen somewhere that it was not offered with AWD. The 2006 RWD V8 has a six speed.

I have a chart at work--I'll look it up

next2pool
07-16-09, 12:36 PM
So much for going by memory--I was off a year on the v8 6 spds. Let's try this again:

the V6 used the 5L40E from 2005 thru 2007. In 2008 with direct injection, it went to the 6L50E

the v8 4.6 used the 5L50E from 2005 thru 2006. In 2007 it went to the 6L50E

I don't see anywere that the FWD and AWD had any differences in trans applications.

The STS-V has used the 6L80E since SOP

WillySTS
07-16-09, 01:08 PM
So much for going by memory--Let's try this again:





I don't see anywere that the FWD and AWD had any differences in trans applications.



I think you meant RWD, since FWD and AWD are definately different.

next2pool
07-16-09, 01:23 PM
I think you meant RWD, since FWD and AWD are definately different.

I sure did!! Man, I just can't seem to get this right :)

next2pool
07-16-09, 01:42 PM
I just realized that if you move the shifter over to manual mode and keep tapping it up, it should stop at 5 or 6 depending on which trans you have--even if standing still.

carter's_sts
07-16-09, 06:44 PM
Good point; I guess that would be the simplest way to tell. Thanks for the info.

Side note - I wish they displayed the gear you are in when in automatic mode. Minor thing, but some other cars do this.

next2pool
07-16-09, 07:31 PM
That would be cool.

EChas3
07-17-09, 01:09 PM
So, according to Next2pool's research:


Model - Year & Engine
5L40E - 2005~2007 V-6 (All V-6's without Direct Injection )
5L50E - 2005~2006 V-8 (These cars would also all have a '4' shifter position)
6L50E - 2007~Present V-8 & 2008~Present V-6
6L80E - All STS-V's


The first digit of the transmission model indicates the number of gears. You can also determine the number of gears while driving by moving the gear shift to the right (Sport Mode) and pushing it forward repeatedly until the top gear is displayed on the DIC or HUD.

I do not believe any RPO code indicates the transmission model, but I'm always willing to learn!:o

next2pool
07-17-09, 02:42 PM
That looks right to me, but I do think there are specific RPO's--let me find them.

next2pool
07-17-09, 03:29 PM
OK--here are the option codes:

5L40E RWD M82
5L40E AWD MX5
5L50E RWD M22
5L50E AWD MV3
6L50E ALL MYB
6L80E ALL MYC