PeachParts Mercedes-Benz Forum - View Single Post - Only Using Half The Springs In 722.3 Transmission Reverse Piston

Squiggle Dog · #4 04-03-2016, 06:35 PM

Right. It took me a while to figure out how the setup works. I initially thought that the spring plate hit the discs, but what actually happens is the spring plate is already up against the K1 clutch and the piston works against the springs in order to press on the discs.

So, a harder spring means reverse engages more softly that if it were to have lighter springs.

The discs engaging hard will prevent wear because otherwise they would slip for a brief moment before engaging. By only using half the springs, reverse will slam harder when engaging, but the discs will last longer as they won't be slipping.

The initial problem with the early transmissions was reverse slamming into gear and customers didn't like it, so Mercedes went with heavier springs so that it would softly feather into reverse, but the slipping of the discs wore them down too quickly.

So, a person has to choose between harsh reverse engagement and short reverse life.

When I replaced the transmission in my W116 300SD (722.120), I set the shifts on the firm side to save the friction material, but no so harsh as to jolt the driveshaft and rear axle.

You want to experience a transmission with a firm shift? Try riding in a 1960s W111 220S with automatic transmission featuring a fluid clutch instead of a torque converter. It about bucks you out of your seat shifting up and down.