Virtually all non-overdrive transmissions run at 1:1 in top gear. It doesn't matter whether they are 3 speeds, 4 speeds, or automatics, if they're not overdrive, they're not overdrive. Overdrive is defined as getting more than one driveshaft turn per crankshaft turn. The Borg Warner Overdrive used by Ford and Merc results in a 30% overdrive. It's like getting a whole extra gear on top of top gear. In other words, it takes your 4.27 rear end and makes it work like a 2.99 rear end on the highway. My Merc will cruise at 70 all day long. On top of that, the 4.27 rear gives some spirited launches for a 3500lb car with 115 HP engine. I will warn you that if you swap to a 3.00 rear with your current transmission, starting from a dead stop will be like starting in second gear. You'll have to fan your clutch which is not good in the long run and not good for quick getaways. The rear end ratio of a non-overdrive Merc (in 1951) was 3.91 which I think is still not very highway friendly today but probably a decent compromise. I stick to my original post. Find an overdrive tranny and leave the rear end alone.
No where in here do I see a mention of previous OD trans by the OP, have I overlooked that? Straight pipes, no speedo, no tach, is is possible that you're going faster than you think, and the engine is turning slower that you think, just making lots of noise? Or is your clutch slipping? Seems to me that I recall my parent's '53 Ford Fordomatic had 3.31 gears, the 3 speeds w/o OD were about 3,78 or so , and the OD models had somewhere in the low 4s. First thing you need to do is verify your speed and rpm. Speed can be checked by following a buddy at a predetermined speed or with a GPS. For rpm, maybe you can find somebody with a 6 volt tach you can lay on the seat and rig up some temporary wiring, or maybe a mechanic friend's handheld shop test instrument. Straight pipes on a flathead can hit resonance at certain speeds and rpm that may be fooling you. Without knowing true speed and rpm you're farting in a whirlwind and we're all wasting our effort typing all this shit! Dave
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Dirty: You gotta read all the posts. Original 53 Merc except for tranny swap. Recent engine rebuild, runs great except too high rpms at highway speed. You got to assume the Merc came with an OD and somebody removed it.
I had a 53 Merc with straight pipes, didn't run to good, put those motorcycle type mufflers, (super traps) on the end of the exhaust, back pressure, ran much better. Check what rear you have, mine hit almost 100 in O/D.
It did come with an OD but during the rebuild it was swaped out with the current non OD transmission. I would love to contact the person that rebuilt it but it was an older gentleman that had passed on and i picked it up from a relative that new nothing of it. Also, i knew what speed i was going with someone driving next to me on the phone. And the rpm's were maxed because if i went any faster i thought i was oging to tear something up. I like having a std trans, however my column shifter needs to be repalced" entire column" and i dont want a floor shifter, i enjoy the bench seat and the leg room.
Really need a tach , tire size and fairly accurate speed to know how to continue this conversation. I've had a 305 with 2.5" glass packs that sounded like it was working harder than it was. But, it fooled enough people.
Yea I was going to say the same thing. Most stock flatties won't spin themselves far enough to come apart. No offense to the flat head bunch intended here. I have to agree with sled here. I have a valve in head motor that if I went by the sound of it instead of by the tach I would stop spinning it a good 1500 below the redline. Exhaust noise is deceptive. Replacing the tranny is a 20 dollar cure for a 10 cent problem here. Fix the colum, even if you do replace the tranny you will still have to repair the colum.
I apreciate the help guys. Im just going to look for the original trans if not ill swap it with a different od trans. My column shifter is trashed so what other column could i swap it for and still have a 3 on the tree? I found a 58 f100
If that will bolt up, how much? Also the reason im having shifter issues and need to repalce the colum is the shifter collar is worn out and i cant find a new one.
I don't know if it would bolt up or not. You would have to ask someone smarter than me. Not much Imagine. Do some asking and find out if it will work then PM me an offer.
Well i have an old r10f 1g overdrive laying around thats still good, can i install it on the transmisison that i already have on the car? I found a related article that seems to show that it will work. http://www.streetrodderweb.com/tech/1007sr_borg_warner_overdrive/photo_29.html
I'm from that old school and the first thing we did after buying a car with and automatic was to get rid of it and swap in a three speed with overdrive and a floorshift kit. That said, if you want to keep it an automatic trans use a Ford AOD and swap out the rear end with a later Ford with somewhere around 3.73 gears and cruise in comfort.
You are trying to be traditional when if wasn't traditional even in the day. Until someone discovered tank clutches in Hydramatic and the BandM tranny came on the scene, automatics were not used in the day, especially behind a flathead. No one swapped a stick for an automatic. So use a C4 and you will solve your problems and unless you tell someone, no one will know. I used one in my 51 ford pickup with a Merc flathead and it was cool.
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