Technically Speaking
- Author: Wayne Colonna, Technical Editor
With the 722.6 being a transmission that shifts from clutch to clutch, smooth shifting requires proper shift overlap. To accomplish this task, a number of components and strategies merge to allow for adaptation under various driving conditions. To fully appreciate what it takes to make for correct shift timing and shift feel, it is good to look at and understand these components and strategies independently. And after having a basic understanding of them, one can see how they work together like members of a musical band to harmoniously accomplish the task at hand.
Related Articles
- - The ins and outs of transmission diagnostics
- - Mazda FW6A-EL stored pressure switch codes
- - A 6T70 IMS Invalid Range Signal
Hydraulics
One of the difficulties a transmission technician faces when working with a 722.6 transmission is the absence of pressure taps. Hydraulic pressures are calculated from input signals such as engine torque, engine speed, accelerator-pedal position, cruise-control request, wheel speed, traction status, kick-down switch, selector-lever signal and the program-select switch W/S. If taps were available, there are basically eight different pressure categories (see Figure 1) with their respective range specifications.
Shift Solenoids
There are three shift solenoids, the 1-2/4-5 (Y3/6y3), the 2-3 (Y3/6y5) and the 3-4 (Y3/6y4). Just by their very names you can determine their functions. Obviously the 1-2/4-5 solenoid is responsible for the 1-2 and 4-5 upshifts and their respective downshifts. Then, of course, you have the 2-3 solenoid for the 2-3 and 3-2 shifts, and the 3-4 solenoid handles the 3-4 and 4-3 shifts. Each of these three solenoids is fed with 50-55 psi of pressure called “solenoid shift pressure,” which is controlled by the shift-solenoid “in” pressure valve.
Pressure Solenoids
There are two pressure-control solenoids. One is called the modulating pressure-regulating solenoid (Y3/6y1) and the other is the shift pressure-regulating solenoid (Y3/6y2).
The modulating PR solenoid regulates pressure between 0 and 125 psi, which influences the pressure-regulator valve to increase main line pressure (working pressure) from a static 60 psi to as high as 320 psi depending upon torque input. This modulating PR solenoid oil also influences the 1-2/4-5, 2-3 and 3-4 shift-overlap valves so that the shift overlap of releasing and applying clutches corresponds to torque input.
The shift-pressure solenoid regulates pressure between 0 and 120 psi, which influences the shift-pressure regulator valve for a controlled clutch-apply pressure (shift pressure) during a shift transition only. This transitional clutch-apply pressure (shift pressure) ranges from a low 0 psi to as high as 220 psi depending upon torque input.
Both of these solenoids are fed with a maximum of 125 psi from the line-pressure-solenoid “in” pressure valve.
Solenoid Shift Chart
As a reminder for those of you who have read past articles on the unique solenoid shift pattern this unit has, you will notice from the solenoid shift chart in Figure 2 that shift solenoids 1-2/4-5, 2-3 and 3-4 are toggled on/off to make their respective shifts. While the unit is in the gear they control, they remain off. This explains why when the computer system observes a fault while the vehicle is being driven, the transmission fail-safes to whichever gear it was in at the time. When the vehicle is brought to a stop and the ignition is cycled, the transmission will remain in second gear.
Shift Groups
By viewing the mechanical, hydraulic and electrical operation of a shift, you can observe that a specific solenoid and a group of valves, described as a “shift group,” cause a change in clutch application. A shift group has two phases. The transition from one gear to the next is called a “shift phase.” The second phase, once the shift is complete and the transmission is in gear, is called the “stationary phase.” Three shift groups achieve five forward speeds. In a shift phase, a shift solenoid initiates the application of one group of valves to change the clutches required for that shift. During this time the other two groups remain in the stationary phase.
The three shift groups are:
K1/B1 (gear changes 1-2/4-5)
This group, which controls the upshifts and downshifts 1-2/2-1 and 4-5/5-4, consists of:
• K1 clutch
• B1 brake
• 1-2/4-5 command valve
• 1-2/4-5 holding pressure shift valve
• 1-2/4-5 shift pressure shift valve
• 1-2/4-5 overlap valve
• 1-2/4-5 shift solenoid (Y3/6y3)
K2/K3 (gear change 2-3)
This group, which controls the upshift and downshift 2-3/3-2, consists of:
• K2 clutch
• K3 clutch
• 2-3 command valve
• 2-3 holding-pressure shift valve
• 2-3 shift-pressure shift valve
• 2-3 overlap valve
• 2-3 shift solenoid (Y3/6y5)
K3/B2 (gear change 3-4)
This group, which controls the upshift and downshift 3-4/4-3, consists of:
• K3 clutch
• B2 brake
• 3-4 command valve
• 3-4 holding-pressure shift valve
• 3-4 shift-pressure shift valve
• 3-4 overlap valve
• 3-4 shift solenoid (Y3/6y4)
Computer Strategy
In the beginning of the article, the section under the heading “Hydraulics” mentioned how internal transmission pressures are controlled and calculated from various inputs to the TCM. The TCM uses these inputs to achieve proper shift timing and shift feel under diverse driving conditions through four basic adaptation programs: driving style, shift time, fill pressure and fill time.
Driving Style
This program is ready to adapt to the driving condition as it happens. The TCM constantly monitors vehicle speed and throttle opening as well as the rate of change of the throttle as it opens and closes. It also looks at lateral acceleration, which is a term for curve recognition. Basically, it monitors wheel speeds to determine when the vehicle is in a turn. In addition to these inputs it also monitors the frequency of gear changes. As a result, it can adapt quickly to a shift time and feel appropriate for the present condition. This adaptation, not written to memory, is known as an adaptation that “lives for the moment.”
Shift Time (Shift Overlap)
This strategy focuses on the quality of the upshifts and downshifts under both load and no-load conditions. Shift-time adaptation gives the TCM the ability to electronically alter the time it takes to go from one gear to another; in other words, the time it takes to disengage one clutch while applying another. Once the TCM has calculated the type of shift that needs to take place, the TCM uses the following two strategies to accomplish the task.
Fill Pressure (Apply Pressure)
This strategy gives the TCM the ability to control and modify the pressure used to engage a clutch, which results in the type of shift feel that will occur.
Fill Time (Preload Pressure)
This strategy gives the TCM the ability to control the time it takes to fill a clutch drum, bringing the clutch pack to a zero clearance but not yet applying the clutch. This adaptation compensates for wear of the friction plate.
Scan-Tool Diagnosis
Shift-Time Adaptation (figures 3 & 4)
Specific values are needed to make the shift-time adaptation, and these values are written to memory, enabling the ETC to adapt during the following shift occurrences:
- Accelerating-upshift adaptation: Upshifts that occur under load
- Deceleration-upshift adaptation: Upshifts that occur under no load
- Accelerating-downshift adaptation: Downshifts that occur under load
- Deceleration-downshift adaptation: Downshifts that occur under no load (i.e., coast-down shifts)
These values are represented in Newton meters (Nm), meaning torque; in other words, the strength of the shift. There are no ideal numbers to achieve. For example, if a 1-2 upshift that occurs under load with an eight-cylinder engine has a 190-Nm reading and the shift quality is acceptable, one may consider that the computer is able to handle and overcome the existing clutch clearance or a slight leak in the system without a flare on the shift and possible premature damage to the applying clutch. A zero number indicates that a clutch pack does not require adaptation or the clutch pack has not yet adapted. However, if an adaptation value is at its maximum and the shift is unacceptable, repair work may be required. Additional adaptation cannot be achieved when the following maximum values are reached:
- 8- and 12-cylinder engines + or – 210 Nm
- 6-cylinder engines + or – 180 Nm
- 4-cylinder engines + or – 150 Nm
Fill Pressure (figures 5 & 6)
Fill pressure is measured and presented in millibars (mbar). Higher values indicate that the TCM is increasing fill pressure to produce a firmer shift. Lower values indicate that the TCM is decreasing fill pressure to produce a softer shift. 0 mbar means either that the TCM has not stored an adaptive value or that the shift member does not require correction. A value at the parameter’s upper limit, along with poor shift quality, indicates the need for repair.
Fill Time (figures 7 & 8)
Data parameters for fill time are displayed in cycles of time. The TCM controls the two pressure solenoids with an amplitude-modulated current. Amplitude means the highest value of a periodically varying quantity. The greater the signal amplitude, or difference between the highs and lows of the signal, the greater the pressure. The TCM can change signal amplitude only once per 20 milliseconds (ms). Each cycle displayed by these data parameters equals one 20-ms period. If the scan tool reports a fill-time adaptation of three cycles, this means that it took three periods of 20 ms each (60 ms) to alter pressure enough to accomplish the correct application of the shift member. The maximum fill correction time is 15 cycles, or 300 ms. A value of 0 cycles indicates no fill correction was needed.
Exhaust Circuits
While reading this article you may have asked yourself about the exhausting clutch. There is a shift-overlap valve in the valve body that controls the decrease in pressure of a releasing clutch. In addition, there are checkballs that assist in metering the vented pressure (see figures 9 and 10).
This was just a small glimpse of some of the components and strategies needed to shift a 722.6 transmission. And since this unit does not offer any pressure taps for step-by-step diagnosis, the only eyes a technician has for any diagnosis is a scan tool. And for a scan tool to be of any use, a technician needs to understand the information displayed and have a good overall working knowledge of the transmission’s operation. Otherwise, you may just as well throw a valve body and solenoids on it and see what it does.
FAQs
The 722.6 Shift Strategy - Transmission Digest? ›
This strategy focuses on the quality of the upshifts and downshifts under both load and no-load conditions. Shift-time adaptation gives the TCM the ability to electronically alter the time it takes to go from one gear to another; in other words, the time it takes to disengage one clutch while applying another.
What vehicle has a 722.6 transmission? ›The 722.6 transmission is equipped on vehicles such as W209 CLK350, W211 E350, W220 S500, W463 G500 and more.
Are all Mercedes 722.6 transmissions the same? ›Mercedes has used the 722.6 transmission in a number of different vehicles and in combination with different engines. To accommodate these different vehicle and engine combinations, different converters were needed. Many of the converters were similar in appearance and differed only in their bolt circle or diameter.
How much oil does a Mercedes automatic transmission take? ›Shown here are the filter kit for the transmission (This includes a new pan gasket, filter element, dipstick tube cap, drain plug seals, a quart of Mercedes automatic transmission fluid (approximately 10 quarts are needed overall) and the special dipstick tool you'll need to measure the level of fluid in the ...
How many gears does a 722.6 have? ›Abstract. The 5G-Tronic (model W5A 330 and W5A 580 · type 722.6) is an electronically shifted 5-speed overdrive automatic transmission with torque converter lock-up (typically in gears 3, 4 and 5) and 2-speed for reverse.
Is the 722.6 a NAG1? ›The 722.6 Mercedes-Benz 5G Tronic (or in Chrysler applications, this transmission is identified as the "New Automatic Gearbox Generation One", or NAG1) is an electronically controlled 5-speed transmission. The 722.6 transmission is equipped in large variations of automobiles from Mercedes Benz to Chrysler.
What year is the 722.6 transmission? ›The 722.6 transmission went into production for use in 1996-model-year vehicles and is still being offered in 2009. The 722.6 is used in Mercedes, Porsche and Jaguar vehicles and in a variety of Chrysler products, where it is referred to as NAG1.
Which Mercedes use 722.9 transmission? ›The Mercedes 7G-Tronic 722.9 transmission is the fifth generation of their transmission line, and it is used in everything from the top of the line Mercedes S-Class, all the way down to the Mercedes C-Class.
What is the pressure on a 722.6 transmission? ›This transitional clutch-apply pressure (shift pressure) ranges from a low 0 psi to as high as 220 psi depending upon torque input. Both of these solenoids are fed with a maximum of 125 psi from the line-pressure-solenoid “in” pressure valve.
How do I know if my Mercedes transmission is bad? ›- The Check Engine Light Is Illuminated. ...
- You Notice a Transmission Fluid Leak. ...
- You Hear Whining, Buzzing, and Humming Sounds. ...
- The Transmission Is Slipping. ...
- You have Difficulty Shifting Gears. ...
- You Smell a Burning Odor.
How do I bypass Mercedes limp mode? ›
You can attempt to bypass Limp mode by restarting the vehicle after a short wait or by removing one of the battery terminals to reset the electronic systems.
Why would I need to reset my transmission? ›If you find any loose or faulty connection in the solenoid or its components, it will severely harm the TCM, causing abrupt failure. This is one of the primary reasons transmission control modules go bad and require resetting or replacement, depending on the extent of the damage.
How much fluid does a 722.6 hold? ›Fluid capacity for the 722.6 is as follows: Transmission including Torque Converter, 8 Litres. Transmission Exluding Torque Converter, 4.5 Litres.
How often should you change automatic transmission fluid in Mercedes? ›Your Mercedes Benz automatic gearbox oil and filter should be replaced every; 5 Speed - Every 40,000 miles or 4 Years [whichever is the soonest].
How much does it cost to change transmission fluid on Mercedes? ›Luckily, transmission fluid replacement is a simple procedure when performed by experienced technicians. The fluid change often costs between $500 and $600. The exact price will depend on your model and the type of fluid your car requires, however, $100 is the average cost for both manual and automatic transmissions.
What does a 722.6 weigh? ›Weight: 50.0 lbs.
Do gears have a max speed? ›Once the gear becomes part of a meshed pair, there are firm limits on the maximum speed that a gear can operate. For worm gear pairs, the practical speed limit is 1,800 rpm. These gears require a lower speed than others because a concentrated section of the worm is in constant engagement with the worm wheel.
Is the Mercedes 5G Tronic reliable? ›The Mercedes-Benz 5G-Tronic (also known as 722.5) is known to be quite reliable, but transmission repair specialists frequently have to deal with the failure of 5-th gear in this transmission. The problem is caused by transmission fluid shortages or pressure issues.
Who makes transmissions for Mercedes? ›The Mercedes-Benz holding company Daimler is one of the few car manufacturers who designs and manufactures their own transmissions. For a long time, Daimler has been using numbering 722, which means automatic transmission of the car.
Do Mercedes use torque converter? ›It has two reverse gear ratios. The transmission can skip gears when downshifting. It also has a torque converter lock-up on all seven gears, allowing better transmission of torque for improved acceleration. The transmission's casing is made of magnesium alloy, a first for the industry, to save weight.
What transmission does AMG use? ›
AMG SPEEDSHIFT® MCT 7-Speed Transmission.
What is the oldest automatic transmission? ›The 1904 Sturtevant "horseless carriage gearbox" is often considered to be the first true automatic transmission. The first mass-produced automatic transmission is the General Motors Hydramatic four-speed hydraulic automatic, which was introduced in 1939.
Do Mercedes have transmission problems? ›If you own a Mercedes-Benz, you know that it is a luxury vehicle that is built to last. However, like any other car, it is prone to issues and problems, especially as wear and tear begins to build up over time. One of the most common issues that Mercedes-Benz owners encounter is transmission problems.
What are common problems with 722.9 transmission? ›As usual, the simplest things can lead to major problems in the 722.9. The majority of the failures we've run into are caused by the O-rings on the tips of the solenoids deteriorating, leaking fluid, and not properly stroking valves (figure 1).
How reliable is 722.9 transmission? ›Nearly from introduction, the 722.9 transmissions have been known to have issues with shifting. The early converter based AMG models had slow and sluggish shifting as well as harsh downshifts when slowing to a near stop. Over time, Mercedes has made improvements through software revisions and the use of new fluid.
What is the difference between 722.9 red and blue? ›The two variants will be referred to as the red-fluid version, and the blue-fluid version. The red-fluid transmission service intervals are 40,000 miles, and the blue-fluid transmissions need servicing every 70,000 miles.
How strong is a Turbo 700 transmission? ›The torque that can be handled by a 700R4 transmission varies depending on its production year. Nonetheless, you can expect a max engine torque around 350 lb-ft and a max gearbox torque of 650 lb-ft.
What problems will low transmission pressure cause? ›Along with gear slippage, low transmission fluid levels can also cause low levels of pressure, which leads to slower engagement when shifting gears. If you notice your transmission takes a second to engage when put into drive or reverse, it could be due to low fluid levels.
How do I increase transmission pressure? ›Raising line pressure is typically done by using a stronger pressure regulator spring, installing a larger boost valve or doing both. Sonnax offers several products which raise line pressure and, more importantly, vary the rate of pressure increase.
How long should a Mercedes transmission last? ›According to the experts at our Mercedes-Benz service center, a typical automatic transmission should last around 150,000 to 200,000 miles–that comes out to roughly seven years of use.
What are 3 common signs of transmission trouble? ›
- Refusal to Switch Gears. If your vehicle refuses or struggles to change gears, you are more than likely facing a problem with your transmission system. ...
- Burning Smell. ...
- Noises When in Neutral. ...
- Slipping Gears. ...
- Dragging Clutch. ...
- Leaking Fluid. ...
- Check Engine Light. ...
- Grinding or Shaking.
Speed sensors, the MAF, MPS and TPS; to name just a few of the essential monitors within your engine. All of these send signals to the control units, so as with faulty wiring, if one of these monitoring units is not functioning correctly, then it could send a message that causes the car to enter limp mode.
What triggers limp mode? ›In automatic transmission vehicles, the car will automatically go into limp mode if there is any fault with the transmission. The limp mode is also activated when the transmission control unit determines that the vehicle's clutch is broken, damaged, or defective.
What is the main reason for limp mode? ›Likely causes for your car entering limp mode range from faulty engine sensors and wiring to low fluid levels, such as engine coolant and oil. More serious issues include gearbox and clutch malfunctions or brake problems.
What are the signs of a bad transmission solenoid? ›- Delay shifting upon acceleration and deceleration.
- Your transmission is stuck in neutral.
- Rough shifting.
- Engine revs loudly even when you apply the brakes.
- Your transmission cannot downshift and the engine is loud.
- Unpredictable shifting.
- Trouble shifting into higher gear.
- Trouble downshifting.
- Getting stuck in the same gear.
- Poor fuel economy.
- Check engine light comes on.
Disconnecting a battery will not typically reset the transmission. However, it may reset the vehicle's computer systems, which could affect how the transmission operates.
What cars use a 722.6 transmission? ›The 722.6 transmission is equipped on vehicles such as W209 CLK350, W211 E350, W220 S500, W463 G500 and more.
What kind of transmission oil does a Mercedes 722.6 take? ›Automatic Transmission Fluid (1 Liter). (ATF 4134) MBZ Approval: 236.14. NOTE: This is a high performance fluid designed to optimize shifting performance. For use with the 5-Speed 722.6 & 7-Speed 722.9 Transmission.
Does Mercedes recommend transmission flush? ›Mercedes-Benz Transmission Fluid
If you don't routinely change your fluids at least every 30,000 miles or so, you may find that your Mercedes-Benz transmission will slip.
Does changing transmission fluid make it last longer? ›
Though changing transmission fluid can't fix mechanical problems, it does make for smoother shifts and can extend the life of your transmission. And even when manufacturers recommend fluid change intervals of 150,000 miles under normal conditions, it may be a good idea to change it more frequently.
How often do you have to flush brake fluid on a Mercedes? ›How Often Should I Change the Brake Fluid in My Mercedes-Benz? Our service experts recommend you change the brake fluid in your Mercedes-Benz every 2 years or 20,000 miles, whichever comes first.
What happens if you don t change automatic transmission fluid? ›If you don't replace your transmission fluid, it will break down much like engine oil and lose its lubricating and cleaning properties. This leads to high temperatures, sludge buildup, and excess friction, which can damage the internal clutches that shift the gears.
Is it better to flush or drain transmission fluid? ›It's been said that a transmission flush is more effective than a change because: With a flush, all the old fluid is removed by a flush machine and replaced with new fluid, allowing for optimal transmission performance.
How do you know if your transmission fluid needs to be changed? ›- Puddles under your car. ...
- Roaring sounds when you accelerate or go around corners. ...
- Difficulty shifting. ...
- Engine revving when going around corners.
- A chattering noise when you start driving. ...
- A slight burning smell.
- Warning light.
If your vehicle is due for a transmission service, our Mercedes-Benz master-certified technicians can ensure that your vehicle runs smoothly for many miles to come by performing the following: Transmission pan and torque converter drained of oil. Transmission pan removed, inspected, and cleaned.
What transmission does Rolls Royce use? ›The exception was Rolls-Royce, which manufactured its own versions of the Hydra-Matic transmission under license in Crewe, England, for use in Rolls-Royce and Bentley passenger cars.
What transmission does Porsche use? ›Porsche Doppelkupplung (PDK)
What cars use 722.9 transmission? ›- Mercedes-Benz CLS500.
- Mercedes-Benz S550.
- Mercedes-Benz CLK63 AMG.
- Mercedes-Benz CLS63 AMG.
- Mercedes-Benz E63 AMG.
- Mercedes-Benz CLK550.
- Mercedes-Benz E550.
- Nissan Magnite. ...
- Hyundai i20 N-Line. ...
- Kia Sonet. ...
- Honda City. 2020 Honda City. ...
- Skoda Slavia. Skoda Slavia. ...
- Honda City e-HEV. Honda City eHEV Powertrain. ...
- Maruti Suzuki Grand Vitara. Maruti Suzuki Grand Vitara. ...
- Mahindra Thar. 2020 Mahindra Thar.
Which is the fastest transmission in cars? ›
Generally, a dual-clutch transmission shifts faster than a standard hydraulic automatic transmission with a torque converter or a single-clutch automated manual transmission.
What transmission do NASCAR run? ›Used by the top NASCAR teams, the Andrews A431 Transmission is a proven design with a supporting record of wins. Andrews provides a highly engineered transmission designed for durability and smoothness of operation.
What transmission does McLaren use? ›Is the McLaren 720S automatic? The McLaren 720S has a 7-speed dual-clutch automatic with manual shifting mode. Essentially, it's both, but we recommend Jupiter drivers drive it in automatic mode at the track.
What transmission does BMW use? ›It is common for a specific BMW model to have a transmission made by either GM or made by ZF. For example, E90, E91, E92, and E93 platforms came with either a 6 speed ZF GA6HP19Z or the 6 speed GM GA6L45R automatic transmission.
Which transmission is used in Audi? ›Manual transmissions
All transmissions from Audi are state-of-the-art, and this applies to the manual transmission as well.
The maximum fill capacity on the 722.9 7-Speed transmission is 9.5 liters (10.03 Quart).
Who makes Mercedes 7G-Tronic? ›