overdrive question

[40cpe]

Originally Posted by FRANK PKNY

Perhaps I'm misinterpreting what the overdrive does? I thought when the transmission freewheels you are in Over Drive? When my relay kicks in it goes out of the freewheeling mode. This seems incorrect. However I stand to be corrected if free wheeling is engaged without the overdrive being activated. When the solenoid is engaged I do not get free wheeling, if I understand you correctly this is correct? Now I'm not trying to be difficult but from the way I see it, I thought the free wheeling was in play in the OD mode only? Am I incorrect here? If I'm incorrect then the OD is working properly>

Your overdrive is operating correctly. You can readily see the difference if you will put the truck in high gear before 28 mph and accelerate to about 60 mph without letting up on the accelerator. Then let up on the accelerator until the engine is braking the truck. Then get back on the accelerator to cruise mode. You will hear and feel the difference in engine rpm. Overdrive reduces the engine RPM about 30% from non-overdrive. If you will pull the OD handle out (do this while stopped for now), the truck will operate like a non-overdrive transmission.

[FRANK PKNY]

Interesting Ole Don, I did check the fluid it seemed very clean and the viscosity seemed good. However I may try your cure. Thanks


40 cope I need to try your suggestion also. Thanks Frank PKNY

[rotorwrench]

While locked in overdrive, the planetary gear set reverses the motion of the sun gear when you let off the throttle. This is what allows the pawl to engage the gear plate and stop the motion of the sun gear after the balk ring moves out of the way. When it shifts into overdrive you can tell its a different ratio of gearing as soon as you press back down on the throttle. The allowance of reverse rotation on the sun gear is made possible by the over running clutch but it also give the car a coasting affect much like an automatic transmission. Then you lock the transmission out by either pulling the cable control or shifting into reverse, the shift rail repositions the sun gear to lock it with the planetary cage & pinion assembly so that the car can have some engine braking again and pretty much act as a standard manual transmission.


I use AeroShell 100 or 100W (no Plus or + TCP additive) aircraft engine oil in my Mercury transmissions. It is SAE 50 motor oil which is equivalent to SAE 90 gear lube. I've never had a problem with shifting but I'm in a warmer climate than most.

[FRANK PKNY]

I got home from work early enough tonight to work on the BW OD unit. I have a pair of monitor (led) lights hooked so I CAN SEE THE GOVERNOR ground at about 30 MPH and then see the relay send 12v to the solenoid All systems work as they should. I hooked up a tachometer/dwel meter wired to reach into the cab and taped it to the steering column. with this set up I could compare the RPM at a fixed speed. I chose 40MPH down the road I went, everything works as designed. The reason I thought that it was not working properly was because I thought free wheeling meant that I had OD locked in. Which is not the case. I was under the impression that I was not in OD because the freewheeling at below 30 MPH. The tachometer verifies the drop in rpm at the test speed indicating that the overdrive works. The cure for the original problem came from repairing the grounding points in the solenoid.The phenolic insulator that rides on the plunger shaft was broken off, therefore grounding all the time. That kept the kickdown function from working properly. ALL IS WORKING NOW!! I'M a happy old man tonight.

[40cpe]

Good on you for sticking with it and seeing it through.

Thanks for reporting back with the fix.

[FRANK PKNY]

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I got home from work early enough tonight to work on the BW OD unit. I have a pair of monitor (led) lights hooked so I CAN SEE THE GOVERNOR ground at about 30 MPH and then see the relay send 12v to the solenoid All systems work as they should. I hooked up a tachometer/dwel meter wired to reach into the cab and taped it to the steering column. with this set up I could compare the RPM at a fixed speed. I chose 40MPH down the road I went, everything works as designed. The reason I thought that it was not working properly was because I thought free wheeling meant that I had OD locked in. Which is not the case. I was under the impression that I was not in OD because the freewheeling at below 30 MPH. The tachometer verifies the drop in rpm at the test speed indicating that the overdrive works. The cure for the original problem came from repairing the grounding points in the solenoid.The phenolic insulator that rides on the plunger shaft was broken off, therefore grounding all the time. That kept the kickdown function from working properly. ALL IS WORKING NOW!! I'M a happy old man tonight.

[rotorwrench]

A friend of mine had an old 1963 Galaxie 500 fordor sedan with a 352 & R11 OD. He was hard on it with the 352 but the old 352 was aging. He replaced the 352 with a 390 from an old police car and it really came alive. He liked having 6-speeds if he wanted. He managed to crater the 9-inch pinion bearings in that thing. After repairing the 9-inch he put in a super T-10 4-speed and ran it a while before getting an old 67 Fairlane tudor hard top to play with. He wished he hadn't put the 4-speed in the Galaxie after a while. It never had the top end with 1:1 drive that it had with OD. Those T85 transmissions with the R11 OD are tough sumbeaches.