OD ****** issue

51merc

51merc

Junior Member
just returned from cruisin the coast and on the way down lost the OD and reverse. during the trip, the ****** thumped, like it was suddenly thrown out of OD, and it was. thought i'd check the reverse at the next light, and sure enough, it was gone, too. here's the strange part....no reverse, but still have first gear, on the same lever, etc....no OD, but it's free wheeling like it is in OD. was hoping maybe the OD lever had jumped back, but it was still in OD. pulled out the handle, and it still free wheels like it IS in OD. remembering what happens when it gets stuck in OD, i.e. won't go in reverse, won't even ROLL backwards, i jacked it up, removed the OD solenoid, ratated the tires a bit, but still no reverse, no OD. now i'm embarassed to say, i have let the OD run dry before, but when i checked that, it was a little low, but not much. I'm thinking/hoping maybe the sun gear is our of wack or something? any ideas folks?
 
I couldn't say what it is exactly, but I'd wager you have some destroyed parts in the OD. The OD locks out reverse, and maybe what ever went "thunk" froze that function. I've heard that dreaded thunk before, only on mine it was the sun/planetary gears melting together.
 
I never liked the Ford OD trannmission. The BW Ford 54 car and ruck is a much better unit and will bolt right up to a flathead Bell housing. Drive shaft yoke will have to be changed and possability the shaft shortened. I think this is the T-85, but not sure.
 
The overdrive units on the back of all 49-54 Ford transmissions is the same R-10 unit. The only Borg-Warner overdrives bigger and better are the R-11 units used behind big blocks and blown motors.
 
The mid 1951 Mercury and on up to 53 at least has a different lock out rod than the earlier 49 though early 51 trannys had. When you select reverse gear, it pushes a portion of the rod mechanism into a groove in the solenoid operating pawl which locks it & keeps the transmission from being shifted into overdrive. If the pawl is locked in overdrive, it may not be able to push in there since the pawl is out of possition. Check your solenoid and see if it is functional before disassembling anything else. It may be hanging up in the overdrive "on" possition for some reason. I've also heard of the pawls breaking which could jam the thing so it can't be shifted out. Worse come to worse some parts of the plantetary may have busted. You'll have to pull the tail shaft to find that.

Kerby
 
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