R9 Overdrive

Posted by Bill Capron On 2014/2/20 0:57:57

I have recently purchased a '48 with R-9 overdrive. When I first got the car running and driving the overdrive would "coast" properly but not engage.
I diagnosed this problem to a open circuit kick down switch. I was able to clean the switch and the overdrive worked perfectly! It would engage easily and kickdown under full throttle.
Now the problem, I'm driving down the freeway at about 65-70 MPH and the overdrive locks itself out! It basicly downshifted from overdrive to 3rd gear abruptly without warning. Since then it operates as if the lockout cable has been pulled out. It does not freewheel when coasting or make any attempt to engage. If you floor the accelerator like you were trying to cause the overdrive to kickdown it causes engine missfire ( required for kickdown to happen). The lockout cable appears to operate normally. I have changed the fluid in both the transmission and overdrive unit since this has happened. The drained fluid looked ok, no metal debris.
Can anyone point me in the right direction?