My 1994 F-150 grinds when I put it in Drive for about 20 seconds then makes a horrible clunk sound and then it seems ok. If I put it directly into 1st gear it doesn't make the grinding sound and once I'm moving I can select Drive and it's fine until I come to a stop. Could this be a valve body problem? Or do you guys think the tranny is toast? Any help would be greatly appreciated!
Neil

 

I would suggest a overhaul of the trans.

 

I'm not that great with that series, however if it uses a one-way roller clutch for first gear? I'd say it's probably toasted. One of the tricks to see if it's good or bad on some makes is to use 'drive' gear...and it makes that sound...Then shift to manual 'first' gear..and the sound goes away and everything is normal. The manual 'first' gear uses the clutches/bands, and does not rely on the one way clutch.

S-

 

You guys were both correct, thanks for the help.