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In the diagnostic system, go to: Control Units/Drive/ETC/Adaptations.
This sub-menu will allow you to read the data showing the current condition of your transmission providing the filling time, the switching time, and the filling pressure. A cursory explanation is provided in the screen to allow one to obtain an idea of what the data means.
If I understand it correctly the solenoids pulse in 20 ms cycles allowing hydraulic pressure to be applied to the clutch packs. As the clutch packs wear, additional cycles are required to take up the slack. When cycles rise above 10 (200 ms or greater), the delay in clutch pack engagement begins to become obvious to the driver. Maximum allowable is 15 cycles (almost a third of a second delay).
It appears I'm going to begin planning on a transmission rebuild in the next one to two years; K2 and K3 clutch pack response times are fine but...K2 takes 10 cycles to fill on upshift and downshift, clutch pack K3 takes 11 cycles on upshift and downshift (200 ms and 220 ms respectively). Makes sense as these are the gears that have large amounts of torque applied to them on a regular basis. Brake pack B2 shows good response time but fill time is at 5 (100 ms). The other clutch and brake packs are very close to optimal.
Not many people realise that the main benefit of electronically controlled transmissions is that the wear of the clutches and brakes can be monitored and compensated automatically, so that you DON'T notice the clutch engagement times. At least, not unless the wear exceeds the adaptation limits, and then the shifts would have a ****** or a flare.
This doesn't apply to engagement of reverse gear, which is purely mechanical, and can take a relatively long time....
I rebuilt my 722.6 recently, and can offer advice. The first thing is to get a copy of the ATSG 722.6 manual if you haven't already; that's a no-brainer.
I put a link to the ATSG manual for the 722.6 in my trans thread for those interested. One interesting page I found was this one. It also defines why k2 is the most likely to fail, it is used a bunch like Barry said, in high torque shifts.
It should be noted the clutch packs for k2 now have been upgraded in WIS to use 240 (Maybach) chassis clutch packs. Mercedes found out they under rated that clutch stack
I rebuilt my 722.6 recently, and can offer advice. The first thing is to get a copy of the ATSG 722.6 manual if you haven't already; that's a no-brainer.
Nick
I have a copy of the ATSG manual and am toying with the idea of rebuilding the transmission myself. I'm not afraid of mechanical devices but do want to ensure I have the proper tools. Any advice on "must have" tools for disassembly and reassembly? I seem to recall some type of tool that applies pressure to the clutch packs so they can be shimmed properly. Stuff like that and oddball sockets and what not....
There really aren't very many.
The most difficult bit is getting the tranny in and out, and I'd recommend a cheap motorbike scissor lift for that.
Unless the engine mounts are shot, you don't need to support the engine.
Pay special attention to removing the dipstick tube before doing anything else.
You can probably get away with keeping the exhaust and prop-shaft in place (though I didn't).
You need a good set of torx and E-torx socket bits, like any MB work.
I used a cheap electric impact driver to get the rear nut off - need a special socket for that.
The rest of the transmission is held together with a variety of snap rings.
The only remotely difficult bit is compressing the piston springs - I used a drill press and some tooling.
Otherwise you just have to remove the valve block before removing the innards etc etc.
Do all the work one clutch at a time. Everything revolves around the clutches, not the gear-sets.
Make sure you understand how to re-assemble B2 & B3 before you remove them - its important to get all the holes aligned.
Regards, Nick
Last edited by Welwynnick; May 29, 2017 at 11:21 AM.
so if you rebuild are you going to put in a high stall torque converter while its apart ? trying to determine if that would be worth it when it happens
I will note to people reading this if you do the Sneaky ECU reset you wipe out all your adaptation values for the trans and for some, this will cause issues.
That is where my issues with my current trans started.
I would agree. I had a terrible 722.6 in my CLK320, them moment I reset the values it went from bad to garbage and every shift turned into a hammer.
I am honestly unsure how smooth the shifts should be in a 722.6 I've only driven mercs with wonky 722.6's... even my e55, when I drive super slow shifts very smooth, if I gun it it's again smooth, but if I do regular people speed I can tell it's shifting almost like a manual. I'm afraid of having transmission issues, it makes my gut wrench just thinking about it.
I am honestly unsure how smooth the shifts should be in a 722.6
So smooth that you shouldn't be able to feel them. Do you know that many german taxis are E class-es? When they "die", they actually live a second live in my contry, as taxis again
It hurts me when I get on a beaten 2-litre MB diesel taxi with 400 000 miles and I can't feel a thing when it shifts. Yet mine makes sure I never have any kidney stones and it only has 60 000 miles on it, and it's a petrol.
So smooth that you shouldn't be able to feel them. Do you know that many german taxis are E class-es? When they "die", they actually live a second live in my contry, as taxis again
It hurts me when I get on a beaten 2-litre MB diesel taxi with 400 000 miles and I can't feel a thing when it shifts. Yet mine makes sure I never have any kidney stones and it only has 60 000 miles on it, and it's a petrol.
Okay yeah then mine are worn out :'( that's scary... so now what do I do? Pay $5000 for a rebuild????
So smooth that you shouldn't be able to feel them. Do you know that many german taxis are E class-es? When they "die", they actually live a second live in my contry, as taxis again
It hurts me when I get on a beaten 2-litre MB diesel taxi with 400 000 miles and I can't feel a thing when it shifts. Yet mine makes sure I never have any kidney stones and it only has 60 000 miles on it, and it's a petrol.
Are you sure? I think there are variants on these trannys for different performance applications, ie: higher power cars have beefier components and will 'punch' a little more. I think they run higher pressure in the lines too.
I did. If you are worried get the dealer to scan your car.
Is there any sense in just driving the car until catastrophic failure in the tranny? When the clutchpacks wear out you're left at the mercy of the fluid right? You can still manage to drive at the cost of smooth shifting I would imagine.
Okay yeah then mine are worn out :'( that's scary... so now what do I do? Pay $5000 for a rebuild????
I don't know about the States, mate. But it seems in line with what I've seen around MB World. I guess it boils down to your plans about the car. I, for example, have spend time and money to find a really nice CLK that I want to keep for at least ten years and keep it pristine. I've found the best mechanic in the country who will return my transmission to factory condition for a very sane amount of money. So it makes sense to me. If I had no intention to take care of the problem whatsoever, I'd get rid of the car as soon as possible, before something worse happens.
Originally Posted by tw2
I did. If you are worried get the dealer to scan your car.
You mean you've rebuilt your transmission to factory state? Could you share your experience on the transmission's behaviour after it was done?
Originally Posted by skylinrcr01
Are you sure? I think there are variants on these trannys for different performance applications, ie: higher power cars have beefier components and will 'punch' a little more. I think they run higher pressure in the lines too.
I absolutely agree. I know that I know nothing so I read a ton of stuff that people smarter than me have writen. But most of the things I remember are, naturally, related to my run of the mill 722.6.
Is there any sense in just driving the car until catastrophic failure in the tranny? When the clutchpacks wear out you're left at the mercy of the fluid right? You can still manage to drive at the cost of smooth shifting I would imagine.
I only found out when I had it cut out after a high speed overtake. Went out of gear, no CEL, was fine when car restarted. Did it once more and I took it to the dealer and they gave me all the info above and identified K2 clutch as slipping. Code was for inappropriate gear ratio. So don't panic, keep driving and go to the dealer if you notice something or are worried.
Originally Posted by shadenfroh
You mean you've rebuilt your transmission to factory state? Could you share your experience on the transmission's behaviour after it was done?
I had it done at the dealer. It felt the same as before the rebuild obviously without going out of gear. There was no change in shift quality etc. They replaced the whole clutch (don't ask) and all the other friction plates in the other clutches.
I put a link to the ATSG manual for the 722.6 in my trans thread for those interested. One interesting page I found was this one. It also defines why k2 is the most likely to fail, it is used a bunch like Barry said, in high torque shifts.
It should be noted the clutch packs for k2 now have been upgraded in WIS to use 240 (Maybach) chassis clutch packs. Mercedes found out they under rated that clutch stack
Could you be so kind and maybe provide a screenshot of the announcement in WIS concerning the Maybach clutch packs?
Limit value is the maximum allowable value. So long as the actual values are less than the limit value you are good. Negative actual values indicate it is effectively like new.
Clutch pack response time values for your 2-3 shift indicate the greatest wear. Filling time for K2 clutch pack is 180 ms out of an allowable 300 ms. Fill time for K3 clutch pack is 140 ms out of allowable 300 ms. When one or both reach a value of 15 (300 ms) you can expect to shortly thereafter experience what feels like a delayed shift or "slippage" because the clutch plates are worn out.
Personally, when mine reach 14 cycles I plan to bite the bullet and have the transmission rebuilt on my scheduled downtime. Much preferable to being stuck on the side of the highway 200 miles from the nearest dealership or trusted transmission shop. That's the beauty of the ability to monitor the health of the transmission.
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722.6 transmission clutch pack wear determination
