First my apologies if I missed recent posts on this subject. In the last three months I have have several eye surgeries and still can barely see out of one eye.. so much for the whining. I am close to finishing a '49 Coupe, and have changed to at ~'53 flathead and a '51 Ford OD trans. The car was originally not an OD six cyl. car. I know the rear ends are different, and do not really plan on using the OD unless one longer interstate driving. Sooooo my quistion is from others doing this what can I expect from this combo, such as speed required to comfortably cruse on interstates and so on. Also non OD speeds on regular highways with the different gearing, as well as regular highway driving using second gear in OD. Thanks a lot for any help.
I don not know how far along you are in this project, but I'll post this anyway. My apologies if you have already solved these problems. The main problem you are going to run into is that the mount on the '51 transmission is not in the same location as that on a '49. Ford made this change to accommodate the new for 1951 Ford-A-Matic transmission. IIRC, the mount is further forward on the '51 than the '49. I can't give you any hints on how to accommodate this, as I have never had to solve this problem. Perhaps you can get the '51 transmission crossmember and drill some new holes in the "X"-member? All I can tell you is that it is not a direct bolt-in. In addition to the transmission, you will need a bunch of other components. Just about everything you need is available, although some of it may be expensive. In addition to the OD transmission, you will need the relay, the wiring harness, the kickdown switch, and the lockout cable assembly. There are also a couple of minor brackets involved. This change has been done may times, but it was simpler when a complete donor vehicle was available. Trying to piece it together complicates the task. Don't let this deter you, as a properly functioning overdrive on these cars is a real pleasure to have. Also, while there are several shortcuts that can be taken to make the OD "semi-functional" I would strongly suggest doing the whole factory installation to get maximum benefit from the upgrade.
You can buy a Plug-n-Play as Factory wiring harness form Rhode Island Wiring including correct color code wires. A few years back I bought a relay and kick down switch from Dennis Carpenter. If you've built the car up to this point you for sure can install the rest of the package.
I am going to assume that this car has the flathead V8. You will need to stay with the 49-51 Ford bell housing and starter plate and related clutch release parts. The side cover (shift housing) on the 51 trans is slightly different than the 49-50 versions but everything should swap over. You can also swap over the complete side cover assembly of the 49-50 onto the 51 transmission if you wish. The overall length of the complete transmissions is the same from 49-51 so there’s no change to a different driveshaft. The one difference on the 51 tail housing is that Ford relocated the “foot “ on the tail housing by several inches as stated above. You may have to create a custom plate to adapt the bolt hole locations for the motor mount. All of the overdrive controls are the same for these years.
It looks like your non-OD ‘49 came with a 3.73 rear end so using a 28” diameter tire (stock) and the 1-1 3rd gear ratio you are at 2300 rpm to drive 51 mph. When running in OD the 3rd gear is now .70 and the same 2300 rpm returns 73 mph.
Kinda doing similar with a merc. Adding an od trans. Stock gears are 3:92. The OD cars were around 4:27 Will probably only wire up the solenoid to a switch and add the pull cable. Got an od like that now. Ya have to remember that switch.
tubman Thanks much for the detailed reply. I was aware of all the things you mentioned, and have compensated for them already. Just need to finish an adaptor bracket for the cross member hole change. I do have all the rest of the components you listed, include a now kick down switch. My biggest concern was running at internet speeds in OD with the wrong rear end bogging down my motor, which was why my question about maybe running ~55-60 in second gear OD. Will be hooking up the driveshaft and trans levers next week, so anxious to pull it out of the shop on it's own power....
'51 Ford OD had 4.11 gears and non OD had 3.78. I ran my '51 with OD and a 1954 3.54 gears and axles. Pulled it fine. This time when I put an OD back in it it is getting 4.11 gears again cuz my 3.78's are noisy and the donor 4dr has 4.11 ! Dave
This is my'49 Tudor... originally equipped with a 6 cylinder and overdrive transmission...I removed the 6 cyl. and replaced it with a (stock) Mercury V-8. This rig I would , on occasion, tow my boat. I never checked the rear gear ratio, thinking it was probably 4/11? It towed well...'never needing to go past 55 mph!
I would also use the governor as this will take it out of overdrive when you slow down and come to a stop. I have heard that these units don't like the torque of starting off in low gear while in OD. If you are like me, I bet you may forget to turn the switch off at a stop. then you would be in OD and start off in first.
I did that 60 years ago on a 49' F-1 and it worked great.... Probably had 4:11 gears... I don't remember.... Made a good highway cruiser out of that truck.... I just bought another 49' F-1 ... New TOY .... Going to Montana next week to pick it up.... LynnW
UPDATE: Making progress, slow but sure. Making an adaptor bracket to offset the '51 OD trans to the '49 crossmember. Also have the clutch linkage hooked up. However, still a bit confused on the shift linkage. I am leaving the three on the tree set up. Only thing I have come up with so far is this diagram, which is a bit small to figure out. I am asking for help with a larger diagram, or actual pictures of the shift linkage. As always, thanks much
So, what is it you need to know exactly? The 2 shift rods should hook up exactly the same between the 2 different trannys. No doubt they will take a little fine tuning to get Neutral in the right place for the shifting.
Appreciate the info... May seem simple, but we have changed a lot on the drivetrain on my Shoebox, and pulled the engine/trans over two years age, so having some trouble figuring out where the rods go, as well as if we have all the parts after two years.. Therefore a good picture or diagram would help a lot..... and yep, I am an (80) year old with a lot of issues, so please be patient with this old dog.
I don't have a photo of the arms in stock application. I do know that the rods connect to the trans arms same as the arms on the column. Meaning the arm closest to the firewall is 1st and Reverse. It goes to the arm on trans closest to the tailshaft housing. Closest to the steering box goes to arm closest to the Bellhousing. Past that I can't be of much help. Any photo of that part of 49 to 59 column shift will tell you what you need to know.
Yes you can but Anthony was talking about not using the governor using just a switch to "turn it on and off" and by doing this if you forgot to turn the switch off, you would start off in 1st OD. Or like you said, 2ond gear but without turning the switch off it would still be in OD. The governor is a good safety item to knock it out of OD. And believe me, I have forgotten to turn my switch off a few times and if not for the governor I would have started off in 1st OD.
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