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722.6 Slow shifting: fixed today by replacing trans conductor plate

13557 Views 26 Replies 6 Participants Last post by  Dave2302
The silver S430 has been getting a lot of TLC from yours truly. This stuff is fun. :)

The transmission's shifting felt kinda sluggish. It's never failed to shift, and it's not in limp-home mode, but the shifts would feel just slightly klunky--no banging noises, just a feel--and it was starting to get very gradually more mushy, if you will. There were no codes. It'd probably be fine for another 10,000 miles, but I just don't like sloppiness on a Benz. Better to deal with it sooner, when I can take my time and do it right.

Some Googling and STFF'ing said something about the speed sensor typically causing this, and the way to deal with one of those on the 722.6 transmission is replacing the conductor plate with a new one. Since I already had a plate handy, I thought, might as well try an experiment.

Sure enough, it worked. Shifts did firm up considerably, which I consider a good thing. The "klunky" feeling is pretty much gone. I had done the transmission fluid and filter exchange (the full 14 liter version) about 5,000 miles ago, and apparently dropping the tranny pan really does result in a loss of nearly exactly 4L of fluid. Four more liters of the good stuff took care of things. Also replaced that made-in-Taiwan Meyle filter with a genuine M-B filter, as well as a new trans electric connector (also M-B brand). Hey, those have to come out anyway, so might as well, right?

The job took me about 5 hours, since it was my first one, and as usual, I'm doing it on the street, i. e. no lift. Actually, since my buddy's borrowing my jack, I did it with the car's front end up on a pair of Rhino Ramps. :) Yes, it can be done. It's a little awkward getting the valve body back in, especially if you have long arms, but it's certainly doable. Next time, it'll probably take me about 2 hours since I now have a better idea of how to do it.

While I was at it, I checked the resistance of the solenoids. All of 'em are right within spec; matter of fact, they're at dead-center of the acceptable range.

Miles on the car are 143K. Tonight's test drive was a pleasure. Well, driving that car always has been, and now it's even more so.
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The w220 generation of the 722.6 is suppose to be the one with the better internals. I actually have internals of 01 s55 transmission in my storage for my w140 along with a lsd. I have been told my 722.6 was bad 50,000miles ago but knock on wood the tranny is still good it only leaks a quart in a month. Did you do the shift lock linkage? Its easier to do with the conductor off. Also it would have been a perfect time to do the filters in the valve body and replace the springs. I have done the conductor on a w210 and w202 it took me 4-5 hours the first time and about 1-2 at the shop on a lift with air tools and a buddy. The valve body is sensitive to dirt and small particles.
Yes i was refering to the screens on the solenoids. The w220 has the reliable 722.6 transmission. It recieved the "updated valve body". There is a seal that goes on the shifter linkage and once that goes bad its a pita to replace. The pressure springs sometimes snaps or atleast on the pre 2000 model transmission it was really common. I am going to do the valve body in my w140 when i get days off from work so i can barrow the car lift might even get the internals replaced with the s55 trans i have in storage. I have a really bad habit of buying parts and keeping them in storage. For example in my storage i have brand new leather set, a lorinser body kit, and 18" monoblocks not to mention s600 door panels, b pillars, steering wheel and wood set all for my w140.
The fuel consumption gauge was spot on with my s65. I drove non stop from oregan to california and i was shocked that i averaged 23mpg. Then again with my w140 i averaged 28mpg on the same road before. I was extremely tired on ride back to california because we took a greyhound for 1100miles non stop with no sleep and bought the s65 and drove back to California non stop for another 1100miles. I was knocked out cold when i got home. The only down side is you get sleepy with the w220 esspecially the 04-06 models which have no aux port (i have retrofitted a fm transmitter connected through the factory bluetooth) audio sounds clear as a CD.

But it looks like you wont have aux issues since you have an 03. By the way 06 model w220 did not have tape players either but mp3 dvd playback was supported.

Have a safe trip
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