1949 Chrysler Fluid Drive Shift problem

I've looked at many posts and don't find a problem like mine. My fluid drive down shifts fine. (seems most of the problems are in that area) In low range it upshifts as it should. However in high range, the upshift from 3 to 4 happens as soon as i take foot off accelerator - no coast & clunk, just bang & jerk. This happens about 70% of the time. If I push in the clutch as I let off the gas, it will delay and shift correctly - no clash & jerk. I just bought this very original car and the previous owner-who seems very knowledgable about fluid drives has changed the fluid in trans., using 10 weight oil. I haven't checked it, but I assume it is full. Any help will be appreciated.

You may need to clean the governor. Sometimes they get oily or dirty and the points don't work correctly. You can take the cap off and clean the points with brake clean spray or electronic contact cleaner. Drag a strip of white paper between them till it comes out clean. The points are silver so don't be too aggressive.

Thanks, Rusty

I haven't had a chance to check the governor. But since the down shifts are perfect and the 1 to 2 upshift work fine I'd think the governor is working. Looking at some other posts, I wonder about the accelerator linkage needing lub., but the fact that the 1 - 2 shift is ok it is still a puzzle!! I'll probably look at the linkage first as it will be easier than getting under the car to clean the gov.

Thanks

There is a switch on the carburetor that is supposed to control the down shift, it is actuated when the throttle is completely closed. It, or its wiring, may have something to do with the shifting problem.

I lubed the throttle linkage, added a small spring and no more jerk, clash - just the good old fluid drive coast, clunk!!!!!!! I'm 8 for 8 on a short test drive, but I think it's fixed.

Thanks, Frank