First off, I want to say thank you to everyone who has tolerated my extreme low knowledge and all the questions regarding the 49 ford I inherited from my father. The car is a 49 ford coupe with an 8ba flathead with a 3 speed and r10 overdrive. The car has been fully rewired for 12v negative ground. My next question is why would the overdrive try to kick in with the cable pulled out which should lock it out? For the driving I do with the car, I plan on leaving the overdrive locked out. At least until I can figure out what's going on with the unit itself. It is full lubricant wise, so thats no issue because advice from a known overdrive user stated the governor may be dry therefore causing the noise. Well that's not the case so I can eliminate that part. When the cable is pulled which should be locked out, I can shift through the gears fine and it engine brakes as it should, and I can park it in gear instead of reverse like I have to with the od engaged. Once I reach 30ish mph, it sounds like the od tries to engage still. I'm stumped. Could the relay be troublesome being it's still the original 6v relay that uses the glass tube fuse( I don't think dad replaced it when the car was rewired) or the solenoid? ( still original one) or governor? Sorry for the long post, but I don't know where else to go. Thank you!
Remove the fuse from the overdrive relay. Then get under the car and make sure the cable for the overdrive is locking out the lever all the way.
Go the electrical section in the manual. Then go back up to figure 8 and locate the shift rail lock out switch, bottom right of the drawing. It sounds to me like the switch is either failed in the closed positions or bypassed, thus trying to engage the pawl when the o/d is locked out. Probably the easiest way to trouble shoot that is to pull the fuse, lock out the o/d, and see if the problem goes away. That’ll narrow it down. If you continue to operate it with the pawl blocked and the solenoid trying to engage, you might just cook the pull in winding from heat-it only operates briefly, then internally (in the solenoid) switches over to the lower draw hold in coil. As stated above, the cable travel has to be correct to actuate that lock out switch. https://www.oldwillysforum.com/forum/TechData/BWOverdriveManual.pdf
This manual is the universal guide for this transmission but each car brand used different wiring for the activation. 49-51 Fords and Mercurys didn’t utilize the shift rail lock out switch.
My GM cars don't have the "lock out switch" (or even a spot for them). But first make sure the arm on the trans (that holds the lock out cable) is going all the way onto the stop to lock out. They system is always energized when above 23-25 mph (unless the lock out switch is in there), the only thing that keeps it from going into o/d is the cable. Generic schematic since not all cars companies use the lockout switch.
It looks like it might be. Use an Ohm meter to check continuity with the cable pushed in and out, it should be open with the cable is pulled out. This just disables the relay if the cable is out, which is less wear on the solenoid contacts. If the lock out arm is moving stop to stop with the cable then something else inside could be worn. Pull the fuse or wire from the relay and disable the system until you get it fixed. Check this out if you haven't already. https://www.fordification.com/tech/overdrive.htm
1oldtimer jogged my foggy memory. My 55 T86 R10 o/d didn’t have that switch either, or I missed it completely. So that may be a non Ford (or GM) drawing. I don’t know if there’s other internal differences if you don’t have that switch.
I have been wondering about this also. My trans is a '57 Ford unit with the R11 OD and it does not have the lock out switch. From the way it looks, the shaft that moves forward and back when the cable is pulled "blocks out" the solenoid from full stroke, preventing the unit from going into OD. I have wondered if this would burn out the solenoid by not letting it travel far enough to turn off the "pull" coil. I would think the "hold coil" can stay energized but the "pull coil" should not.
The Jalopy Journal
