Mercedes 722.6 transmission -
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Old 08-16-2012, 12:18 PM
Lupin..the..3rd's Avatar
Lupin..the..3rd Lupin..the..3rd is offline
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Join Date: Oct 2005
Location: Arlington, VA
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Default Mercedes 722.6 transmission

If you have an electronic 5-speed Mercedes 722.6 automatic transmission (aka 5G-TRONIC), and you are experiencing slipping or hard clunk during 2-3 and/or 3-4 shifts, the solution is an easy one.

This transmission was used in a bunch of models, C, E, S, SL, ML, CL from late 90's through late 2000's. It's also used in many Chrysler vehicles, Charger, Magnum, Challenger, 300, Durango, Nitro, Wrangler, Cherokee, Commander.

There's a pressure control spring in the side of the valve body that is known to break, and intermittent strange 2-3 or 3-4 shifts are the result. Don't get talked into a spendy transmission overhaul! The solution is both cheap and inexpensive!

The replacement part is Sonnax 68942-01 and is available from a number of sources online. I ordered mine from here. It was about $17 shipped.

Checking or replacing this spring is easy, especially if you're doing a transmission fluid flush already. Drain the fluid from the pan, remove the torx screws around the perimeter of the pan, and then remove the pan. On the passenger side of the valve body is a long rectangular metal plate, held on with a bunch of torx screws. Remove all the screws. Now you see two springs and two caps. Remove the rear-most cap. The spring you're after is under this cap. It should pull straight out. Inspect the spring to see if it has broken, and if so, use a pick to retrieve the remaining piece from inside the bore.

"Installation is the reverse of removal"

Torque spec for all the torx screws holding the metal plate to the side of the valve body is just 4 Nm. (35 inch/pounds).

You'll need about 5 liters of fluid to refill the transmission.
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Last edited by Lupin..the..3rd; 08-16-2012 at 12:24 PM.
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Old 08-16-2012, 01:13 PM
APKhaos's Avatar
APKhaos APKhaos is offline
Join Date: Dec 2002
Location: McLean, VA
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There are a number of tricks with the 722.6, and this is one of them.
The conductor plate connector is renowned for leaking trans fluid. There's an updated connector and seal to solve that problem. Might be worth looking at that if you are dropping the trans pan.
Tony K
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