50 overdrive

J

JHFORD51

Senior Member
My 50 ford has been giving me some trouble lately with the O.D. Trouble started with O.D. engaging as designed but once you drove it 10-15 miles the O.D. would disengage. I added an additional ground wire directly from one solenoid mounting bolt to the chassis with no change. Removed solenoid, cleaned points, and it bench tested fine with crisp engagement. Today, I unhooked all the factory wiring to rule out the govenor, relay, etc. and operated the solenoid directly from a toggle switch. I hear/feel the solenoid clicking but never get any O.D. lock-up. My next step is to install a different solenoid and repeat testing. Can the wires within the solenoid can lose insulation and break down so that the solenoid works with no load but not be strong enough to push the pawl into the spinning ring when the transmission is turning?
 
Still 6 volts? Running a generator or alternator. Bench test usually don't prove anything except engagement - once installed things change. If you're still 6 volt & generator then grounds need everything as well as correct gauge wiring- have you done any rewiring?
 
Hi I had a problem like that on my 49 Merc. The problem causing mine not to shift in to overdrive was the switch on the back of the overdrive. This switch is used to keep from shifting in to overdrive while going in reverse. The switch will stick open and after a while driving it will close and shifting will work. The switch was removed on later overdrives. Don't know if your vehicle has that switch.
 
The answer to your last question is no. A breakdown of insulation isn't a problem unless the exposed wire makes contact with ground. No contact = no problem.

These solenoids are very sensitive to voltage drops. Anything less than 6 volts and they don't like to throw. You can rig up a voltmeter to the solenoid feed wire and test from there.
 
Try this: Unhook the wire on the relay that comes from the switch. Then make a wire with 10 gauge copper and hook it from the starter solenoid to the relay where you unhooked the switch wire. Test drive........
 
as noted in original post, I have already ruled out all the factory wiring by running my own temporary 10 AWG wiring directly from back of ign switch through a 360 watt rated toggle to the solenoid. I have also added a direct 10 AWG chassis ground from solenoid body to framerail. Battery is fully charged on charger for testing. Today, I swapped solenoid to another one with same results. I can literally feel the solenoid clunk into place in the pawl when I engage the toggle but only get freewheel action. I did hear some slight growling today when the solenoid was engaged and the tailshaft was hotter than the main case immediately after the test drive. Guess I am R&Ring the trans...
 
Sounds like you're going to have to dig into the trans. As a side note, did you confirm that you in fact had the solenoid correctly installed? It must be inserted 90 degrees from its normal vertical position, engaging the OD shift pawl, then rotated to vertical so the bolt holes line up. At this point you should have tried pulling the solenoid out. If correctly engaged, it would only pull out perhaps 3/4" before stopping....yet you feel spring tension. If it came right out in your hand, it was not correctly engaged.

Assuming you had done this already, I suspect something internally to the trans.
 
The poster who said he had it fixed is not the original poster. I checked his previous posts and he is mostly on the Model a board. All of this is my reasoning, I think he posted a response on the wrong thread.
 
40cpe said:
The poster who said he had it fixed is not the original poster. I checked his previous posts and he is mostly on the Model a board. All of this is my reasoning, I think he posted a response on the wrong thread.
Click to expand...

I'm thinking the same thing of post #8.
 
I wish had pulled the trans, rebuilt it, and stabbed it back in overnight! Plan to tackle this during my Christmas break; I'll likely overhaul another trans and then R&R. Thanks for the comments and suggestions. I suspect something in the planetary hub but we shall see...

One question for MacVP, does the 49-50 ford car share the same synchro assembly as the earlier 40-48 car (and up through 52 F-1) truck? Aftermarket parts catalogs are all over the place in their respective numbering system with with everything from 1938 to 1962 part numbers being quoted. Ideally a fellow would like to have all the replaceables (seals, synchro rings, thrust washers, etc) on hand before opening everything up for the job.
 
The synchro assy is the same as the '46-54 units. The '40-44 synchros were essentially the same but used a different hub and inserts. The bronze rings were the same between the two types. Beware of the complete synchros sold out there today. Most are incorrectly made. We get the phone calls all the time. Chances are you may only need to replace the rings anyway. Poorly made rings are out there too sadly....

Total disassembly of the overdrive trans will take several hours. The entire job (in our shop) is a solid 11-12 hours labor......and we've done plenty of them. If this is your first one it'll take longer. So don't plan on knocking the job out overnight.
 
Thanks for clearing that up; I'm wary of cheap bearings and cheap brass. O.D.s aren't my favorite but I have done one before.
 
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