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Mercedes 722.9 Preliminary Information, Part 1Mercedes 722.9PreliminaryInformation, Part 1by Mike SouzaThe Mercedes 722.9transmission has beenaround since the laterpart of 2004, but there stillisn’t a lot written about it. The722.9 can be found in theseMercedes vehicles:2004-06 – SL5002005-up – CL500, E500,S430, 500, SLK350,55 AMG2006-up – C230, 280, 350,CLK350, CLS500, E350,E63 AMG, R350, 500,SLK2802007-up – CLK550, CLS550,CL600, CLS63 AMG, E550,E63 AMG, GL320, 450,ML350, 500, ML63 AMG,R63, and S550That’s a lot of vehicles! This 5thgeneration transmission is the first 7speed automatic produced by MercedesBenz. The Mercedes designation forthis transmission is New AutomaticGearbox 2 (NAG2) or 7G–Tronic.Along with seven forward speeds thisunit also has two reverse gears ratios(similar to the 722.6) depending onwhether it’s in Sport or Comfort mode.Shift StrategyShift strategy improvementsinclude: Computer reaction time is 0.1second shorter. Downshifts are shortened byup to 0.2 seconds. Coasting downshifts are shortened by 0.4/2.5 seconds.3030-mikeS309.indd 30 37-47 MPHacceleration times are shortened by 23-28% (modeldependant). Fuel consumption is reducedby up to 4%. Noise levels are reduced dueto lower engine speed in 5th,6th and 7th gear at constantvehicle speed. Flexible adaptation to vehicleand engine.Variable ShiftProgrammingThere are two basic shift programsthat can be varied by the customer(similar to the 722.6) using the S or Cbutton on the Electronic Shifter Module(ESM):1. S (Sport) 1st gear starts Normal shift points Reverse gear 1 (3.416:1)2. C (Comfort) 2nd gear starts Earlier upshifts and laterdownshifts Reverse gear 2 (2.231:1)The transmission will start in firstgear if any of these conditions apply: 1st gear is selected manually. ¾-throttle to full-throttleacceleration from start. Cold engine temperature (precatalytic warmup).Emergency Functionor Limp-Home ModeThere are a variety of failsafemodes: If a solenoid doesn’t work theaffected gear is blocked. Forexample: if solenoid Y3/8y7or the B3 clutch is defective,you won’t have 1st, 7th orreverse in S mode. If a hydraulic fault prevents agear from engaging, the previous gear will remain applied. If the computer defaults tolimp mode while driving,it’ll turn all solenoids off.GEARS March 20092/11/09 2:33:57 PM

Figure 1Solenoids that are normallyopen will allow full pressureto selected clutches and thetransmission will be in 6thgear. After shifting to park, oilpressure from K2 solenoid isThe payment processor you rely on for service and stability.ExclusiveMember-OnlyCredit Card Programredirected to the B2/BR solenoid by emergency operationvalves, and the transmissionNEW GM FACTORY TECHNICIAN’SGUIDE NOW AVAILBLE!Toll Free (800) 428-8489 Fax (805) 604-2001Email bookstore@atra.com Website www.atrabookstore.comSave money on your credit card processing.First National Merchant Solutions – an industry leader with over 50years experience – is pleased to offer you an exclusive, members-onlyprogram. Competitive rates. First-rate service. Cost savings. These arejust a few of the benefits to you and your bottom line!Your payment processing program includes:t /FHPUJBUFE NFNCFS POMZ SBUFT t 2VBMJĕFE TFSWJDF SFQSFTFOUBUJWFT BWBJMBCMF IPVST B EBZ t "O BDDPVOU NBOBHFNFOU UFBN t PNQSFIFOTJWF POMJOF SFQPSUJOH Call 800.354.3988 for your Free ConsultationAsk for Shayne Tobaben or Bruce Lonneman 35GM 6T40/45 Technician’s GuidePlease mention this ad when placingyour order. Place your order before12pm PST and receive same day shipping.GEARS March 200930-mikeS309.indd 31312/12/09 12:00:17 PM

Mercedes 722.9 Preliminary Information, Part 1Figure 2Figure 3Figure 4will now provide reverse, and2nd gear with the selector indrive (figure 1). Electronic ControlComponents Here’s a diagram of the components that make up the electronic control system (figure 2). Transmission Control Module(Y3/8n4) (flash capable) Working Pressure ControlSolenoid (Y3/8y1) (line/normally open) K1 Clutch Solenoid (Y3/8y2)(normally closed) K2 Clutch Solenoid (Y3/8y3)(normally open) K3 Clutch Solenoid (Y3/8y4)(normally open) 3230-mikeS309.indd 32B1 Brake Clutch Solenoid(Y3/8y5) (normally open)B2 Brake Clutch Solenoid(Y3/8y6) (normally closed)B3 Brake Clutch Solenoid(Y3/8y7) (normally closed)Torque Converter LockupSolenoid (Y3/8y8) (normallyclosed)Normally Closed: high current, highpressure; no current, no pressure.Normally Open: no current, high pressure; high current, low pressure.Normally open solenoids are usedfor limp mode with no current to thetransmission.Two Oil Floats Oil Control Float 1 (31) Oil Control Float 2 (32)Fluid Level Float Function 2The extended length of the transmission (41mm) allows oil to sloshforward during hard stops. To preventoil foaming from gears running in fluid,Mercedes added a front float.Three Speed SensorsThese components are built intothe valve body assembly (figure 3): Turbine RPM Sensor (Y3/8n1)(Front) Internal RPM Sensor (Y3/8n2)(Center) Output RPM Sensor (Y3/8n3)(Rear / Hall Effect) Selection Range Sensor(Y3/8s1)GEARS March 20092/12/09 11:00:22 AM

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Mercedes 722.9 Preliminary Information, Part 1Unlike the Lepelletiergeartrain, the 722.9geartrain has thesun gear fixed to theK1 clutch assembly,located in the front ofthe unit (figure 6).three clutch packs to provide sevenforward gear ranges and two reverseranges. 4 Multi-Disc Brakes 3 Multi-Disc Clutches No SpragGear ratios are achieved with oneRavigneaux and two simple planetaryassemblies shown in figure 5. Unlikethe Lepelletier geartrain, the 722.9geartrain has the sun gear fixed to theK1 clutch assembly, located in the frontof the unit (figure 6). The Ravigneauxplanetary assembly is also located in thefront section of the transmission (figure7). There are two simple planets locatedtoward the back of the transmission,one in front of the other (figure 8).Fluid TypeFigure 5Range Sensor FunctionThe Y3/8s1 range sensor isbuilt into the ECM ribbon cable, andcan’t be replaced individually. It’s aPermanent Magnetic Linear ContactlessDisplacement (PLCD) sensor; it has apermanent magnet mounted to the manual valve, which changes the magneticfield and output voltage as you movethe selector. If the sensor signal doesn’tregister properly with the computer,it’ll put the system into limp mode.Speed Sensor FunctionThe 722.9 uses three speed sensors to monitor transmission operation(figure 4):1. The front speed sensor (Y3/8n1)monitors turbine speed (input shaft3430-mikeS309.indd 342.3./ small ring gear).The center speed sensor (Y3/8n2)monitors the Ravigneaux carrierspeed (ring gear of rear planet).The rear speed sensor (Y3/8n3)monitors the park pawl gear (exciter ring/2 Hall Effect).The magnets for these sensors aremolded in a plastic ring and securedinside nonferrous flanges.The 722.9 uses a newly-developed,suggested-use-only transmission fluid,referred to as ATF 3353 (figure 9). Itpromises a higher friction consistency,thermal stability, and temperature rating. ATF 3353 can also be used onprevious model 722.3/.4/.5/.6 transmissions. This special ATF is availablefrom Shell & Fuchs Europe oil suppliers in 1 liter bottles under MercedesBenz part number A001 989 45 03 10.No scheduled maintenance isrequired for the 722.9 (fill for life).In the next issue we’ll go intosequential shifting, powerflow, andsome unusual features associated withthe Mercedes 722.9.Transmission FluidTemperatureThe transmission fluid temperaturesensor is built into the TCM, and isn’treplaceable separately.Clutch ComponentsThe 722.9 uses four brakes andGEARS March 20092/11/09 2:35:23 PM

K1 ClutchAssemblyFigure 6RavigneauxPlanetary GearsFigure 7PlanetaryAssemblyFigure 8GEARS March 200930-mikeS309.indd 35Figure 9352/11/09 2:35:50 PM

E63 AMG, R350, 500, SLK280 2007-up – CLK550, CLS550, CL600, CLS63 AMG, E550, . The payment processor you rely on for service and stability. Save money on your credit card processing. First National Merchant Solutions – an industry leader with over 50 years experi