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:( I have a 70 Impala with a turbo 400 trans. Once the car is warmed up it shifts into gear very hard. The hotter the car is like after driving for awhile when shifting to drive or reverse it really slams into gear. The idle speed is set correctly. Any suggestions would be appreciated. I'm not sure if some kind adjustment can be made or am I looking at rebuilding it . THANKS
 

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ratboy7070 said:
:( I have a 70 Impala with a turbo 400 trans. Once the car is warmed up it shifts into gear very hard. The hotter the car is like after driving for awhile when shifting to drive or reverse it really slams into gear. The idle speed is set correctly. Any suggestions would be appreciated. I'm not sure if some kind adjustment can be made or am I looking at rebuilding it . THANKS
OE t-400 suffered with a ruff reverse engagement

common issue if the trans has a shift improver kit installed. IS this a recent change or a long time complaint?? Did you recently purchase the car??

Worn boost valve , bad vacuum modulator will raise main line pressures so a ruff engagement happens.

GM installed reducer cup plugs in reverse servo feed bore to ease this engagement.
 

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Use a vacuum gauge to check idle speed vacuum level at the modulator. Vacuum should be 15 inches or higher at idle for proper "garage shift" engagement. Less than that will cause high line pressure and harsh engagement.
Use a gauge!!
 
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