Hi, I have a 1970 W30 with a 400 turbo transmission that during low speeds, between about 20 and 25 mph it seems to be at odds as to what gear to be in,
1 or 2nd. Only happens at low speeds and not during harder acceleration. It's
kind of hard to explain, anyone else experience this ? Any ideas ?

Thanks

 

Check the lines to your modulator, make sure the rubber lines are not cracked or leaking. When you pull off the line at the modulator, if there is trans fluid in there, replace the modulator.

 

Hello - Did you ever figure this mystery out? I have the same condition, only between 2nd and 3rd gear between 30 & 35 MPH. I have a new modulator and a new vac. line.

Thanks -

 

Is your modulator the adjustable kind? It should shift into 3rd at somewhere around 20-25.

 

No I have not , haven't had a lot of time to drive and experiment with it. There is no fluid in the vaccum line and the modulator is new. I will try to
adjust the modulator next. Anyone know which way to go with it ?

 

Turn the modulator screw in(clockwise)to raise the shift timing and firmness. Turn it out(counterclockwise) to lower the shift point and soften the shift.