1969 Dodge Dart Custom Sedan Slant Six, Father-Son Project

A904 Transmission sticky governor Stalling the Motor

The car had one quirk that was pretty annoying. Sometimes, at least once per trip,, when decelerating quickly from a stop, it seemed like the transmission would refuse to downshift from 2nd-to-1st gear. Maybe it was the torque converter misbehaving, the more I think about it?

Whatever it was, the engine would be forced to lug down into the realm of 500 RPM as it came to a stop. Which is so low that it would stall the engine. Months ago, we’d drained the transmission, added new fluid, and changed its filter. But that was the extent of the attention the transmission got. I convinced myself the problem was with the governor sticking from varnish build-up.

So did we rebuild it? Nope! Instead, we added a full can of Sea-Foam Trans-Tune, and crossed our fingers. And you know what, after about 50 miles of driving, it stopped doing that! After a few more trips to confirm it was truly no longer misbehaving, we pulled a transmission cooler line off the radiator, and completely flushed out the semi-new fluid (which looked pretty darn cloudy), replenishing it with 5 qts of Dextron IV plus 2 qts B&M Trick Shift, plus a 1/5 can of Trans-Tune.