The Stovebolt Site Forums The Shop Area Driveline 1950 Tranny fluid drain and change

I have a 1950 3100 with a 4 speed with the enclosed driveshaft. I want to drain and refill the tranny fluid before I put the cab back on the frame (figure it will be easier that way). I have drained the gearbox, but thought I read somewhere that the enclosed driveshaft needs filled also? If so, how do I drain it and where do I fill it? Any help would be appreciated.

Conrad,

If you want to drain the u-joint enclosure, you will have to re-seal it. If gaskets break, that might turn into a more complicated procedure. If the enclosure does not leak (much), you might want to let it be (unless you are hearing noises from inside the enclosure).

The transmission fluid slowly migrates rearward into the u-joint enclosure (and visa-versa).

Fill the transmission to the appropriate level; let it sit a few hours; check and top up to fill level; check and repeat until no change in level.

cornhead,

Just a note....make sure you use straight 90 weight mineral based gear oil as specified in the shop manual.
Many of the new Hypoid gear oils are too slick which could cause double clutching to shift and synchronizer problems. I learned this from experience.

Tim

Tim

Thank you for that info. Sounds like im best to not drain the shaft. The truck has been sitting 25 years. I see no sign of a leak anywhere, nor did one appeare after dolly towing it 20 miles. So if its low or leaked out, the tranny fill plug level will work back into the shaft? Im assuming the fill plug is the one on the passenger side below the breather?

After sitting for that period you may see some leaks once you start using it.