1952 Cranbrook overdrive issue

[John Klosterman]

Update.....I found and corrected a wiring problem with the kickdown switch on my 52 Plymouth overdrive. The wire on the B2 terminal of the kickdown switch was supposed to be wired on the negative side of the coil, but was instead attached to the positive side of the coil.  This caused feedback into the overdrive solenoid making the shift into overdrive erratic.  Correcting this issue fixed the downshifting problem also.  Also, upon the awesome advice from George Asche, I drained the synthetic 75/90 gear oil and refilled the transmission with Synthetic 5W-40 engine oil used in diesel cars. Original literature advised using 40w engine oil.  Apparently the advice NOT to use synthetic oils in this overdrive transmission (R10) is not correct. My transmission now shifts and downshifts flawlessly.  Happy motoring in your Plymouth. 

[Go Fleiter]

I fear You just have to try it out!
As changing the oil is the least job, You should begin so!
Maybe washing it out in its place is sufficient.
If residues of the modern oil still prevent reliable funktion,
it may be necessary to open the OD to clean it up completely.
Than the mechanical parts can be inspected too.
Until now, the reason for disfunction of mine always was
the locking cable not having driven the control lever to its end position.
Moving the handle in and out energetically 2 or 3 times always helped.
  I have added LED- control lights displaying the contact function of
governor, shift rail /lock out switch and the OD relay.
With a tachometer added too, I wanted to learn how the OD lives.
I found all this very helpful to trace malfunctions quickly, that I didn´t
take all this out other than originally planned.
Greetings from Düsseldorf!
Go

[John Klosterman]

I have a 1952 Plymouth Cranbrook coupe with 53K.  It has a 3 speed transmission with overdrive.  When I lock the overdrive out the transmission performs flawlessly.  When I lock the overdrive in, the overdrive usually shifts into 4th gear (o/d) without an issue.  Occasionally, when I shift into high gear, it misses the gear and acts like the transmission is in neutral.  The engine revs up but high gear is not there.  I went through the solonoid and the kickdown switch and all appears normal.  When I got the car the previous owner had changed the transmission gear oil.  I do not know what weight oil he used or if it was synthetic.  I also changed the gear using synthetic 75/90 weight oil.  I now understand using synthetic gear oil can affect the operation of the transmission causing the sun gear not to slide to engage the planetary gear locking the o/d.  Is there any way to get the synthetic gear oil cleaned off of the internal parts so I can put the proper gear oil into the transmission (GL1) so this problem can be resolved without removing and disassembling the entire transmission, cleaning every part?  Help!