RegisterSearchFAQMemberlistUsergroupsLog in
Reply to topic Page 1 of 1
GM 8 speed transmission
Author Message
Reply with quote
Post GM 8 speed transmission 
So anyway, to stop distracting from the OP's thread on the 4L80E I started this thread. My next question to Crazy was going to be...

I'm not up on the new GM transmissions. I know the ZF is supposed to be able to shift straight between gears, like if I'm in 8th gear and the computer calls for 4th gear because I floored it, it shifts straight from 8th to 4th without having to hit 7 then 6 then 5 before getting to 4. Does the new GM transmission do this? Also, what power levels are they rated for? The ZF is supposed to be good for something like 800 ft lbs, for the version used in the Hellcat.

View user's profile Send private message Send e-mail
Reply with quote
Post  
GM 8-Speed 8L90 M5U Hydra-Matic Automatic Transmission
The Hydra-Matic 8L90 (production code M5U) is a fuel-saving and electronically controlled eight-speed automatic transmission developed and produced by General Motors for use in rear- and rear-biased all-wheel-drive vehicles with a longitudinal powertrain orientation. Used in full-size trucks, SUVs, sports cars, and luxury cars, the Hydra-Matic 8L90 is part of the 8LXX family of transmissions that succeeded the 6LXX family.

Designed and built by GM, the 8L90 transmission speed is expected to contribute up to 5-percent greater efficiency, when compared to the previous 6L90 six-speed automatic. Smaller steps between gears, compared to the Hydra-Matic 6L90 six-speed automatic, keep the engine within the sweet spot of the rpm band, making the most of its horsepower and torque to optimize performance and efficiency.

For performance driving in the Corvette, the transmission offers full manual control via steering wheel paddles, and unique algorithms to deliver shift performance that rivals the dual-clutch/semi-automatic transmissions found in many supercars – but with the smoothness and refinement that comes with a conventional automatic fitted with a torque converter.

The 8L90 has a torque capacity of 738 pound-feet (1000 Nm).

Compact And Lightweight

Featuring four gearsets and five clutches, creative packaging enables the 8L90 to fit the same space as the previous 6L80/6L90 family of six-speed automatics. Extensive use of aluminum and even magnesium also make it more than eight pounds (4 kg) lighter than the six-speed (in Corvette applications). Along with design features that reduce friction, the 8L90 is expected to contribute up to 5-percent greater efficiency, when compared with a six-speed automatic.

Five clutches are used, three at a time, leaving only two open clutches in each gear state. Optimized clutch sizing and off axis binary pump contribute to outstanding spinloss attributes.

All applications feature adaptive shift controls. Several features such as grade braking, Performance Algorithm Shifting, and Driver Shift Control are available on some of the applications. Performance Algorithm Shifting (PAS) monitors how assertively the driver is using engine output and other vehicle sensors to determine at what engine speed to upshift of downshift. Driver Shift Control allows the driver to shift the transmission like a clutchless manual gearbox. Electronic safeguards prevent over-revving if the wrong gear position is selected.

The 8L90 uses VFS control components to monitor clutch pressures with optimum accuracy. The result are faster and more precise shifts.

The 8L90’s 32-bit transmission control module (TCM) monitors transmission performance and compensates for normal wear in components such as clutch plates, so performance is consistent for the life of the transmission. The control module also “tests” the components to optimize their interaction on an on-going basis.

The 8L90’s controller analyzes and executes commands,the processor microcontroller executes instruction at a rate of 120 Million Instructions per second, and wide-open-throttle upshifts are executed up to eight-hundredths of a second quicker than those of the dual-clutch transmission offered in the Porsche 911.

The torque converter is 258 mm in diameter and features a lock-up clutch, although clutch and converter specifications vary depending on the application. The 8L90 uses electronic controlled capacity clutch (ECCC) technology, which employs a small, regulated amount of slip to dampen out engine pulses for a smoother running drivetrain, especially during shifting.

Low Maintenance

The 8L90 uses Dex 6 HP Transmission fluid, which was developed to have a more consistent viscosity profile as well as improved lubrication characteristics.


Eight speed RWD / AWD, electronically controlled automatic overdrive transmission with torque converter clutch. Clutch-to-clutch architecture, with external transmission control module
Maximum engine power: 650 hp (485 kW)
Maximum engine torque: 635 lb-ft (860 Nm)
Maximum gearbox torque: 738 lb-ft (1000 Nm)
Gear Ratios
First: 4.560
Second: 2.970
Third: 2.080
Fourth: 1.690
Fifth: 1.270
Sixth: 1.000
Seventh: 0.850
Eighth: 0.650
Reverse: 3.820
Maximum shift speed: 7000 rpm
Maximum Vehicle Weight (GVW): 13,200 lbs (6,000 kg)
Maximum Vehicle Weight (GCVW): 20,500 lbs (9300 kg)
Range selector quadrants: 5 position (P,R,N,D,M) protected for 6 position (P,R,N,D,M,L)
Case description: 2-piece (main, extension, bell integrated with main case)
Case material: Die cast aluminum
Shift pattern: 6 variable force solenoids, one for each clutch and one for TCC
Shift quality: 6 variable force solenoids, one for each clutch and one for TCC
Torque converter clutch: Variable Force Solenoid ECCC, 2 path, turbine damper
Converter size: 258 mm
Fluid type: Dexron High Performance ATF
Fluid capacity (application specific): 10.5 L
Transmission weight (application specific): 95.5 kg – 99 kg, including TCM
Pressure taps available: c12345R Clutch
Assembly site: Toledo, Ohio, USA
Available Control Features
Multiple Shift Patterns (Selectable)
Driver Shift Control (Tap Up / Tap Down)
Enhanced Performance Algorithm Shifting (PAS/PAL)
Engine Rev Matching on TAP Downshifts
Staged Upshifts in TAP Mode
Selectable Tow / Haul Mode (Truck Only)
Engine Torque Management On All Shifts
Altitude and Temperature Compensation
Adaptive Shift Time
Reverse Lockout
Automatic Grade Braking
Additional Features
OBDII
External TCM
Control Interface Protocol – GMLAN
Sponsored Links

View user's profile Send private message
Reply with quote
Post  
I didn't see the shifting behavior on "kick-down". Did I miss it?

View user's profile Send private message
Reply with quote
Post  
It's not specified but I beleive it does jump shifts up and down.
Rev matches and holds gears in corners.

View user's profile Send private message
Reply with quote
Post  
http://www.hotrod.com/articles/the-all-new-8l90-transmission-corvettes-lighter-faster-stronger-auto/



Last edited by CrazyHoe on Fri Feb 24, 2017 7:58 am; edited 1 time in total
View user's profile Send private message
Reply with quote
Post  
https://www.google.ca/amp/www.hotrod.com/articles/the-all-new-8l90-transmission-corvettes-lighter-faster-stronger-auto/amp/?client=ms-android-rogers-ca

View user's profile Send private message
Reply with quote
Post  
Someone build a decent CVT and be done with it.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

moved here
CrazyHoe wrote:
Speeder wrote:
Yeah, that low gearset was a pain but man was it worth it. I'd go through the hassle again (well, not really, not doing any more 4 speeds). All kidding aside about how bad the 4L60E is (not that anyone is kidding), its first gear really gets the trucks moving from a dead stop. A 4L80E has the same ratio for 1st gear that the 4L60E has for 2nd gear, so if you want to know what your trans will be like with the stock gears get in a 4L60E equipped vehicle and take off with the selector in 2nd gear. The computer will take off in 2nd if the selector is in 2nd, as a feature for getting started in snow and ice as it's easier for a vehicle to get moving if it's harder for the vehicle to spin the tires.

BTW, Hughes offers one now too. I have no idea if they are any good or not, and will never buy one. Next time I do a transmission it's going to be at least an 8 speed. I'm REALLY liking the one in the Charger, that car gets down the road in a big hurry, somewhere in the 13.X second quarter mile time, and pulls down around 23MPG mixed driving and as much as 28MPG on the highway.
https://www.summitracing.com/parts/hup-hp2575


Agree, the more gears the better.
Although the 6L80 should be pretty good since the rpm drop from 1st to 2nd is similar to the 4L80, the 8L90 is even better.

The folowing web site finds the GM 8spd better than the ZF 8spd:

http://www.thetruthaboutcars.com/2014/04/saturation-dive-the-gm-8l90-transmission/


the 6l80e has a 1st gear rpm drop closer tothe 60e/65e.70e than the 80e/85e. The 80e is even a closer ratio trans than the newer 8l90e. There is quite a bit more rpm drop with the 8l90 and 6l80e transmissions than with the 4l60e trans, and its horrible on the 4l60e trans, esp with a stock torque converter. While the 80e/85e is the closest ratio of the GM automatics, you are stuck with the high 2.48:1 ratio. The best all around trans gearing wise is the 200R4. Its 2.45:1 isn't super high like the 80e, but isn't as low as the 4l60e trans.

200R4
First - 2.74:1
Second - 1.57:1
Third - 1.00:1
Fourth - 0.67:1

60e
• 1st -- 3.059
• 2nd -- 1.625
• 3rd -- 1.000
• 4th -- 0.696

80e
• 1st -- 2.482
• 2nd -- 1.482
• 3rd -- 1.000
• 4th -- 0.750

6l80e
1 4.027 2nd-2.364 3rd-1.532 4th-1.152 5-th0.852 6th-0.667

8l90E
1st 4.56 2nd-2.97 3rd-2.08 4th-1.69 5th-1.27 6th-1.00 7-0.85 8th-0.65

GM in the future will allow Ford to use its 9 speed auto because Ford will be allowing GM to use its future 10 speed auto.

We are seeing lower and lower 1st gear ratios partially due to the very tall wheels tires, the lack of off idle torque some newer engines are making, the increased weight that newer trucks weigh, to help with in city fuel economy by allowing the truck to move from a dead stop with the least throttle usage possible.

We are moving into new transmission territory that is very high tech and super expensive. There really is something to be said about staying in a GMT400 truck and avoiding such craziness, esp. if you plan on modifying anything from stock.

peace
Hog

View user's profile Send private message
Reply with quote
Post  
Hog wrote:


the 6l80e has a 1st gear rpm drop closer tothe 60e/65e.70e than the 80e/85e. The 80e is even a closer ratio trans than the newer 8l90e. There is quite a bit more rpm drop with the 8l90 and 6l80e transmissions than with the 4l60e trans, and its horrible on the 4l60e trans, esp with a stock torque converter. While the 80e/85e is the closest ratio of the GM automatics, you are stuck with the high 2.48:1 ratio. The best all around trans gearing wise is the 200R4. Its 2.45:1 isn't super high like the 80e, but isn't as low as the 4l60e trans.

200R4
First - 2.74:1
Second - 1.57:1
Third - 1.00:1
Fourth - 0.67:1

60e
• 1st -- 3.059
• 2nd -- 1.625
• 3rd -- 1.000
• 4th -- 0.696

80e
• 1st -- 2.482
• 2nd -- 1.482
• 3rd -- 1.000
• 4th -- 0.750

6l80e
1 4.027 2nd-2.364 3rd-1.532 4th-1.152 5-th0.852 6th-0.667

8l90E
1st 4.56 2nd-2.97 3rd-2.08 4th-1.69 5th-1.27 6th-1.00 7-0.85 8th-0.65

GM in the future will allow Ford to use its 9 speed auto because Ford will be allowing GM to use its future 10 speed auto.

We are seeing lower and lower 1st gear ratios partially due to the very tall wheels tires, the lack of off idle torque some newer engines are making, the increased weight that newer trucks weigh, to help with in city fuel economy by allowing the truck to move from a dead stop with the least throttle usage possible.

We are moving into new transmission territory that is very high tech and super expensive. There really is something to be said about staying in a GMT400 truck and avoiding such craziness, esp. if you plan on modifying anything from stock.

peace
Hog


Nope!

The 6L80 is very close to the 4L80 and the 8L90 has closer ratios.
Having very low ratios mean you can have wide ratio spread and tall rear end which is good for fuel economy.

Divide second gear by first then multiply by rpm at shift and you'll get your rpm drop.

RPM×:
4l60: .53
4l80: .597
6l80: .587
8l90: .651

So while the 1-2 shift drops by half with the 4l60, it only drops by 2/3 with the 8l90.
So shifting at 6k in first would see 4k in second.

View user's profile Send private message
Reply with quote
Post  
10 speed RWD Auto trans 2017 ZL1 Camaro 650hp Direct Injection, Variable Valve Timing, Supercharged, NEW ultra low viscosity trans fluid, internal thermal control circuit, 260mm lockup style torque converter that still uses EC3(ECCC) apply strategy


Clutch


10 speed valvebody


Input gear


Pump


Triple Clutch



Wow does Photobucket ever suck.

Ratios

1=4.70
2=2.99
3=2.15
4=1.80
5=1.52
6=1.28
7=1.00
8=0.85
9=0.69
10=0.64
R=4.87

These transmissions continue to become wider and wider ratios transmissions. Much different than my Powerglide with its 1.76:1 low and 1:1 high gear, for a very narrow ratio of 1.76:1, compared to the new 10 speeds 7.39:1 wide ratio spread, just slightly more than the 8 speed autos 7.02:1 ratio.

I would have liked to see that ZL1 let loose on the banked turns of Daytona on Sunday.
I can hardly wait to see the DOHC V8 for the Vette, plus the 700+ hp engine for the C7 ZR-1.

peace
Hog

View user's profile Send private message
Reply with quote
Post  
CrazyHoe wrote:
Hog wrote:


the 6l80e has a 1st gear rpm drop closer tothe 60e/65e.70e than the 80e/85e. The 80e is even a closer ratio trans than the newer 8l90e. There is quite a bit more rpm drop with the 8l90 and 6l80e transmissions than with the 4l60e trans, and its horrible on the 4l60e trans, esp with a stock torque converter. While the 80e/85e is the closest ratio of the GM automatics, you are stuck with the high 2.48:1 ratio. The best all around trans gearing wise is the 200R4. Its 2.45:1 isn't super high like the 80e, but isn't as low as the 4l60e trans.

200R4
First - 2.74:1
Second - 1.57:1
Third - 1.00:1
Fourth - 0.67:1

60e
• 1st -- 3.059
• 2nd -- 1.625
• 3rd -- 1.000
• 4th -- 0.696

80e
• 1st -- 2.482
• 2nd -- 1.482
• 3rd -- 1.000
• 4th -- 0.750

6l80e
1 4.027 2nd-2.364 3rd-1.532 4th-1.152 5-th0.852 6th-0.667

8l90E
1st 4.56 2nd-2.97 3rd-2.08 4th-1.69 5th-1.27 6th-1.00 7-0.85 8th-0.65

GM in the future will allow Ford to use its 9 speed auto because Ford will be allowing GM to use its future 10 speed auto.

We are seeing lower and lower 1st gear ratios partially due to the very tall wheels tires, the lack of off idle torque some newer engines are making, the increased weight that newer trucks weigh, to help with in city fuel economy by allowing the truck to move from a dead stop with the least throttle usage possible.

We are moving into new transmission territory that is very high tech and super expensive. There really is something to be said about staying in a GMT400 truck and avoiding such craziness, esp. if you plan on modifying anything from stock.

peace
Hog


Nope!

The 6L80 is very close to the 4L80 and the 8L90 has closer ratios.
Having very low ratios mean you can have wide ratio spread and tall rear end which is good for fuel economy.

Divide second gear by first then multiply by rpm at shift and you'll get your rpm drop.

RPM×:
4l60: .53
4l80: .597
6l80: .587
8l90: .651

So while the 1-2 shift drops by half with the 4l60, it only drops by 2/3 with the 8l90.
So shifting at 6k in first would see 4k in second.


Thanks for the correction, I was using the wrong math for about 10 years now. I was wrong, I only hope I didn't lead too many people down the wrong path.

Thanks again Hoe.

peace
Hog

View user's profile Send private message
Reply with quote
Post  
Ah no prob.

It's a little abstract so it's hard to spot the error if you reverse the #.

I'm no math wiz, I just do this kind of math all the time.

Like calculating 1/4 mile times from G force on each gear to determine fastest gear ratios.... Fun Laughing

Now, phone apps are so much more advance.

View user's profile Send private message
Display posts from previous:
Reply to topic Page 1 of 1
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum