Overdrive

Habusailor

Habusailor

Senior Member
My 49 custom does not have overdrive, I see a lot of shoeboxes came with OD. What is the best way to convert to overdrive?

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Most cars of that era were set up to go either way but you will have to find a 1949 or 50 overdrive transmission first. The 1951 units may work but they are different and might lead to a need for some modification. If you find one, you will need to purchase a wiring harness, a control relay, a kick down switch, a lock out cable, and what ever transmission components that might be missing from the transmission itself like the governor, reverse lock out switch, or operating solenoid. The driveshaft may work as is but I'd have to confirm that from the chassis parts book for the shoe box Fords.
 
I have a T86 with OD that needs a new home, but missing solonid, Should fit, although splines may be different.. Brst way is to watch eBay not uncommon for someone to offer the whole shebang, but shipping will be high
 
Not sure what is different with the 51, I know 49/ 50 convertibles with X frame had a special mounting plate for the soloniod so it would clear the frame but sedans where the same.. These trannies all the way up into the early 60's will interchange, May need different clutch plate or drive shaft yoke as the splines were different in some of the later years. Also the taild shaft length may change

http://www.vanpeltsales.com/FH_web/.../Flathead_Trans_8A-6910_ODslidingpawlassy.jpg
 
The transmission mount on a '51 is in a different location than the '49-'50. I think it is further forward. This change was done to accommodate the new for '51 Fordamatic transmission. I am in the process of converting mine and was pleased to see that most of the ancillary parts (cable, kick-down switch, wiring harness, etc.) are readily available and relatively cheap. This is not the case for some of the transmission components (solenoids, etc.).
 
Well, in my opinion, the very best way to make the conversion would be to find a donor car that had all the parts. a rusted out dented up vehicle from a farmers field would be best, but these are very hard to come by any more. putting one together from a part here and a part there may take a while, but is doable. there are many here on the ford barn , and over on the Hamb, that will be able to help you with specific questions.
 
Maybe watch craigslist for a while, I see them sometimes. There's one on Springfield, MO. list now. Way too far for you, but gives an idea.
 
If you want a contemporary hiway speed cruiser, get the od transmission and keep your 3.73 rear. Just watched the od conversion installed in a 51 coupe. Took three old f--ts a weekend laying on a concrete driveway. Ouch! You could always do a "parts wanted" and have the pick of the liter.

It is worth the effort and the bucks. Good luck.
 
I changed my 50 to overdrive earlier this year, 49 and 50 used the same transmission, 51 will work but you'll have to modify the mount. I used a 51 trans and had to weld a short section onto the mount. The mount is wider and heavier on the 51 and as was said earlier the mount is one inch farther forward. Take some basic measurements of the output of your stock unit, center of output to the tunnel and to the frame on either side. I did this and had to make clearance for the solenoid, measurements make it a lot easier. I bought a kickdown switch but haven't installed it because mine doesn't need it, overdrive makes a big difference in the car, I can run with traffic with no problem.
 
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As said before you need to go with the 49-50 transmission. If the reverse lockout switch is bad just bypass it. That was the official Ford replacement part. You have a sedan so you will not need the rocker assembly to mount the solenoid underneath. These transmissions are available as I've seen quite a few at Hershey before. The other parts can also be sourced. Some will tell you they use a toggle switch but when you get one of these hooked up the way the factory did it you'll love the operation.
 
The lock out switch is not just for reverse. Personally, I like to have that switch on there and operational. When you pull the lock out cable, it turns the system off so that the solenoid is not hot when the governor reaches shift speed. I think Ford discontinued its use because owners rarely locked out the overdrive function. If you pull a trailer or live in mountainous areas, you will find more of a necessity to lock out the overdrive and that solenoid uses a good bit of electrical power whether its locked out or not without that switch.
 
I use a toggle switch to turn the power on and off, I too didn't want unnecessary wear on the solenoid/relay when not using overdrive. The relay I'm using can be found at any parts store, since mine is 12v, my solenoid I found on eBay for $51 delivered.
 
amodel25 said:
The '51 transmission is a bolt in in '49 and '50 if you use a '51 rear crossmember.
Click to expand...

I suspect that you have to drill the proper holes in the "X"-member to mount the '51 cross-member; I don't think they're already there. That might get a little tricky.
 
The mount needed a 3/4 inch rise to sit at the height of the stock transmission, a piece of angle steel cut down on one side and welded to the mount and the the holes drilled. This was the best option for me, I've got maybe $20 in it and it works fine.
 
tubman said:
I suspect that you have to drill the proper holes in the "X"-member to mount the '51 cross-member; I don't think they're already there. That might get a little tricky.
Click to expand...

Only the convertibles had the X member. They also have a rocker attachment so the solenoid is underneath the transmission.
 
I should have said "cross member", not "X member"; it may have been a poor choice of terms. I was referring to the inner frame structures to which the transmission support bolts. Since the support has been moved, new holes will still have to be drilled.
 
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