W140 Transmssion - hard shift
07-14-2004, 11:34 AM
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CLK, ML320, 400E, 400SE
W140 Transmssion - hard shift
I have noticed that the 1-2 and 2-3 shifts on my 92 400SE are somewhat harsh - not quite a "thunk", but harsher than I would expect from this car. 3-4 and 4-5 shifts are quite smooth. The transmission is a 722.3
It's interesting because the shift is much smoother until the car reaches operating temperature.
I've noted that the "harshness" is much more noticeable under light load, and in fact on a fast acceleration, the shifts seem quite smooth and quick.
The transmission guy said the pressure to the modulator is within spec. The transmission fluid level is correct and the fluid and filter are new. I've given the vacuum modulator a couple of turns counter clockwise in an attempt to smooth shifting.
I know very little about automatic transmissions, and am also unlikely to ask the transmission guy to dig deaper - as they have not demonstrated much transmission knowledge. I've done a fair amount of searching the archives, but am frankly at somewhat of a loss.
Any thoughts?
It's interesting because the shift is much smoother until the car reaches operating temperature.
I've noted that the "harshness" is much more noticeable under light load, and in fact on a fast acceleration, the shifts seem quite smooth and quick.
The transmission guy said the pressure to the modulator is within spec. The transmission fluid level is correct and the fluid and filter are new. I've given the vacuum modulator a couple of turns counter clockwise in an attempt to smooth shifting.
I know very little about automatic transmissions, and am also unlikely to ask the transmission guy to dig deaper - as they have not demonstrated much transmission knowledge. I've done a fair amount of searching the archives, but am frankly at somewhat of a loss.
Any thoughts?
07-15-2004, 11:50 AM
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93 600SEL
Rsmcmahon,
Had a similar problem on a 87 300e. Turned out that the vacum line leading to the egr had cracked and fallen off. When the car warmed up the vacuum is routed to the egr and the total vacuum decreased and made the car shift hard when at slow speeds.
Hope this helps,
Helga
Had a similar problem on a 87 300e. Turned out that the vacum line leading to the egr had cracked and fallen off. When the car warmed up the vacuum is routed to the egr and the total vacuum decreased and made the car shift hard when at slow speeds.
Hope this helps,
Helga
