From park or neutral into R or D the transmission hesitates too long (flare?) then clunks into gear. Not terrible, but annoying. On the road shifts are nice and smooth. Engine starts/runs very smooth. Performance is OK. Does the modulator effect the shifting at low engine RPM? I have redone all the vacuum lines except the one that goes from the manifold to the transmission modulator. I get 16" at 2000 rpm. I don't know if that is low. I really don't know where to start on this one. Can you tell?
Unless recently done I would change transmission oil, filter and gasket. Should be done every 60,000 km. Made a difference on my car.
Normally vacuum would adjust shift speed down under partial load, but you have a shift problem at idle.
The Mitchell repair guide states the following:
"HARSH ENGAGEMENT WHEN SELECTING "D" OR "R"
Idle speed too high. Check pressure receiving (pick-up)
piston in valve body for ease of operation and correct installation.
Replace valve body (if necessary).
NOTE: Pressure pick-up requires a running period of approximately
2 seconds. Harsh engagement may occur during repeated shifts
between "N" and "D". If harshness takes place within 2
seconds, condition is considered normal."
How long is "too long"? If it is really long, like 5 seconds before it kicks into D or R, might be a sign of a failing front pump. Change your filter if you haven't done so lately.
No, it's more like 1 second. That's why I said that it was more annoying than a nasty problem.
JC201
79 450SL
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