The Ford Barn

jackson · 06-09-2022, 11:55 AM

Stock '50 Merc transmission with OD. Reverse will not engage if the OD control is "in". I have to disengage OD to back the car up.

In the shop manual transmission drawing, it appears there is a cam/lever in the transmission gear shift housing that, when in OD, and reverse gear is selected, forces the rail assembly back, shifting the sun gear into direct drive position.

I assume this lever is either broken or missing. My question is.... can I get at and replace this lever by removing the gearshift housing from the side of the transmission, or will it require removing the transmission and disassembling the whole unit?

Thanks in advance for any help.

Jackson

pistonbroke · 06-09-2022, 03:10 PM

It sound like you have a internal issue with the lockout moving freely. I would pull the transmission and investigate. If you can manually pull it out the OD is working but the rail is not being moved by the reverse lever in the trans case for some reason. When you shift into reverse in over drive the rail slides by compressing a spring in the lockout fork or what ever you call it. I would think the lock out fork is not sliding on the rail. Tim

Mac VP · 06-09-2022, 05:53 PM

The 49-50 (and early 51) Mercury overdrive transmission has a unique side cover with a special lever (7292 in the drawings) that fits onto a pin sticking out of the cover. When you shift into reverse, the 1st/reverse shift shaft bumps this lever towards the rear, which in turn pushes the lockout shifter rail backwards. This is the mechanical method that was used to temporarily move the overdrive gears out of OD mode, allowing the transmission to operate in reverse. Since the lockout rail is spring loaded, it will return to overdrive mode when the driver shifts out of reverse. Here’s a link for the drawing.

http://www.vanpeltsales.com/FH_web/F...hiftr-hsng.jpg

Perhaps your transmission is missing that lever.

jackson · 06-09-2022, 06:46 PM

Mac VP, thanks, from your clear drawing, it appears that lever (7292) is missing or damaged in my tranny. I'm getting along OK by simply taking it out of overdrive when I want to back up.... but would like to get it working properly. Now the question is, can I remove that "unique side cover" and repair/replace that lever, and get it back together again, without dropping the entire tranny/OD. I don't mind tackling that job, but would like first to know that I could get it back together properly through that side panel. Hope there's someone on this site that knows the answer.

I guess an additional question would be.... can I find that part (7292).

Mac VP · 06-09-2022, 08:47 PM

The cover can be removed from the transmission while it’s still in the car. The shifter forks could be the separate type or connected to the shifter shafts in the cover. Note the orientation of the low/reverse fork as it’s offset to the rear. Your shifter housing (cover) must be the one used on the overdrive version of this transmission. It should have a pin sticking out at the inside of the lower rear corner……this pin carries the 7292 lever. If you have the standard 3 speed cover, there’s no easy way to add the pin and the lever. We’ve got the correct cover and the lever if you need them.

With the correct shifter housing for the Merc overdrive transmission, installing it back onto the gearbox can be tricky, especially if doing it on the car. You have to align both shifter forks AND hold the lockout lever (7292) in place with your fingers while fitting the housing back to the transmission.

jackson · 06-10-2022, 06:39 AM

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Mac VP - The transmission and OD is original, and worked as it should before I had a local guy go through the transmission and OD unit. It has not worked correctly since re-installing after a 8 year body-off project. Since it's original, I suspect the tranny has the correct OD version of shifter housing. Your description of the effort required to remove and re-install the shifter housing is a bit scary.... but worth trying. I guess the worst thing that could happen if I can't get it re-installed is dropping the transmission-OD.

I just visited your web-site and am grateful to know where to go for parts. Whoever designed the web site deserves a medal.... easy to navigate and find stuff, and lots of great information for us flathead bigots.

Thanks for your help.

rotorwrench · 06-10-2022, 08:35 AM

The standard side shift type cover will fit right on an overdrive type case. I don't know any reason for a person to do that during repair but it is a possibility. If it has the original shift cover then you just need to replace any missing or damgaged part or parts.

My old OD Mercury transmissions have riveted shift arms on the side cover and they are pita to remove for restoration of the arms with new paint and rubber/brass bushings. This may have been a reason a mechanic may have changed the cover if it was changed.

pistonbroke · 06-10-2022, 09:28 AM

I'm confused here. It seems to me if the cam lever were missing you would be able to engage reverse with the lock out pushed in but bad things would happen to the OD unit. My understanding was that Jackson could not use reverse with the lock out pushed in. That would indicate to me that the cam/lever are trying to do their job but the rail is not moving. What am I missing? Tim

rotorwrench · 06-10-2022, 04:23 PM

The overdrive has a sprag unit in there that will freewheel if the unit is not locked out for reverse. This can get things out of place in the OD shift mechanism that is a PITA to get back in place. It no worky in reverse if not locked out. That reverse lockout has to function. I would leave it locked out till repairs are completed.

06-09-2022, 11:55 AM	#1
jackson Member Join Date: Sep 2010 Location: Lincoln, Nebraska Posts: 54	1950 Merc Transmission question Stock '50 Merc transmission with OD. Reverse will not engage if the OD control is "in". I have to disengage OD to back the car up. In the shop manual transmission drawing, it appears there is a cam/lever in the transmission gear shift housing that, when in OD, and reverse gear is selected, forces the rail assembly back, shifting the sun gear into direct drive position. I assume this lever is either broken or missing. My question is.... can I get at and replace this lever by removing the gearshift housing from the side of the transmission, or will it require removing the transmission and disassembling the whole unit? Thanks in advance for any help. Jackson __________________ 1950 Mercury mild custom. Original flathead, re-built, bored .040 over, Max-1 cam, Offy heads, Edelbrock super duel with Stromberg 48s.

06-09-2022, 03:10 PM	#2
pistonbroke Senior Member Join Date: Feb 2021 Location: Perry Mo. Posts: 841	Re: 1950 Merc Transmission question It sound like you have a internal issue with the lockout moving freely. I would pull the transmission and investigate. If you can manually pull it out the OD is working but the rail is not being moved by the reverse lever in the trans case for some reason. When you shift into reverse in over drive the rail slides by compressing a spring in the lockout fork or what ever you call it. I would think the lock out fork is not sliding on the rail. Tim

06-09-2022, 05:53 PM	#3
Mac VP Senior Member Join Date: May 2010 Location: Cincinnati, OH Posts: 1,465	Re: 1950 Merc Transmission question The 49-50 (and early 51) Mercury overdrive transmission has a unique side cover with a special lever (7292 in the drawings) that fits onto a pin sticking out of the cover. When you shift into reverse, the 1st/reverse shift shaft bumps this lever towards the rear, which in turn pushes the lockout shifter rail backwards. This is the mechanical method that was used to temporarily move the overdrive gears out of OD mode, allowing the transmission to operate in reverse. Since the lockout rail is spring loaded, it will return to overdrive mode when the driver shifts out of reverse. Here’s a link for the drawing. http://www.vanpeltsales.com/FH_web/F...hiftr-hsng.jpg Perhaps your transmission is missing that lever. __________________ VANPELT SALES LLC Cincinnati, Ohio Office: 513-724-9486 www.vanpeltsales.com www.classictransmission.com

06-09-2022, 06:46 PM	#4
jackson Member Join Date: Sep 2010 Location: Lincoln, Nebraska Posts: 54	Re: 1950 Merc Transmission question Mac VP, thanks, from your clear drawing, it appears that lever (7292) is missing or damaged in my tranny. I'm getting along OK by simply taking it out of overdrive when I want to back up.... but would like to get it working properly. Now the question is, can I remove that "unique side cover" and repair/replace that lever, and get it back together again, without dropping the entire tranny/OD. I don't mind tackling that job, but would like first to know that I could get it back together properly through that side panel. Hope there's someone on this site that knows the answer. I guess an additional question would be.... can I find that part (7292). __________________ 1950 Mercury mild custom. Original flathead, re-built, bored .040 over, Max-1 cam, Offy heads, Edelbrock super duel with Stromberg 48s.

06-09-2022, 08:47 PM	#5
Mac VP Senior Member Join Date: May 2010 Location: Cincinnati, OH Posts: 1,465	Re: 1950 Merc Transmission question The cover can be removed from the transmission while it’s still in the car. The shifter forks could be the separate type or connected to the shifter shafts in the cover. Note the orientation of the low/reverse fork as it’s offset to the rear. Your shifter housing (cover) must be the one used on the overdrive version of this transmission. It should have a pin sticking out at the inside of the lower rear corner……this pin carries the 7292 lever. If you have the standard 3 speed cover, there’s no easy way to add the pin and the lever. We’ve got the correct cover and the lever if you need them. With the correct shifter housing for the Merc overdrive transmission, installing it back onto the gearbox can be tricky, especially if doing it on the car. You have to align both shifter forks AND hold the lockout lever (7292) in place with your fingers while fitting the housing back to the transmission. __________________ VANPELT SALES LLC Cincinnati, Ohio Office: 513-724-9486 www.vanpeltsales.com www.classictransmission.com

06-10-2022, 06:39 AM	#6
jackson Member Join Date: Sep 2010 Location: Lincoln, Nebraska Posts: 54	Re: 1950 Merc Transmission question Sponsored Links (Register now to hide all advertisements) Mac VP - The transmission and OD is original, and worked as it should before I had a local guy go through the transmission and OD unit. It has not worked correctly since re-installing after a 8 year body-off project. Since it's original, I suspect the tranny has the correct OD version of shifter housing. Your description of the effort required to remove and re-install the shifter housing is a bit scary.... but worth trying. I guess the worst thing that could happen if I can't get it re-installed is dropping the transmission-OD. I just visited your web-site and am grateful to know where to go for parts. Whoever designed the web site deserves a medal.... easy to navigate and find stuff, and lots of great information for us flathead bigots. Thanks for your help. __________________ 1950 Mercury mild custom. Original flathead, re-built, bored .040 over, Max-1 cam, Offy heads, Edelbrock super duel with Stromberg 48s.

06-10-2022, 08:35 AM	#7
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,018	Re: 1950 Merc Transmission question The standard side shift type cover will fit right on an overdrive type case. I don't know any reason for a person to do that during repair but it is a possibility. If it has the original shift cover then you just need to replace any missing or damgaged part or parts. My old OD Mercury transmissions have riveted shift arms on the side cover and they are pita to remove for restoration of the arms with new paint and rubber/brass bushings. This may have been a reason a mechanic may have changed the cover if it was changed. Last edited by rotorwrench; 06-10-2022 at 04:28 PM.

06-10-2022, 09:28 AM	#8
pistonbroke Senior Member Join Date: Feb 2021 Location: Perry Mo. Posts: 841	Re: 1950 Merc Transmission question I'm confused here. It seems to me if the cam lever were missing you would be able to engage reverse with the lock out pushed in but bad things would happen to the OD unit. My understanding was that Jackson could not use reverse with the lock out pushed in. That would indicate to me that the cam/lever are trying to do their job but the rail is not moving. What am I missing? Tim

06-10-2022, 04:23 PM	#9
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,018	Re: 1950 Merc Transmission question The overdrive has a sprag unit in there that will freewheel if the unit is not locked out for reverse. This can get things out of place in the OD shift mechanism that is a PITA to get back in place. It no worky in reverse if not locked out. That reverse lockout has to function. I would leave it locked out till repairs are completed.