The Ford Barn

1951Flatheader · 11-22-2014, 08:20 PM

Hello everyone,

New to the forum. Finally got some time to start working on my 51 F1, it has the stock 4 speed non synchro tranny behind a well running 239 Flathead.

I was hoping to find out If there is an option to add overdrive to the 4 Speed or if that was only available on the 3 speed trannys?

It still has the 4.27 gears in the rear that I will be swapping out for a little taller set when I get the chance but an overdrive would also be nice. Without changing to a T5 or automatic. Trying to keep it close to stock but updated enough to run at highway speeds.

Any information is appreciated. Thanks.

scooder · 11-23-2014, 06:52 AM

I think your best bet is the three speed overdrive out of say a mid '50's F100. This would be column change though, there are ways to convert to floor change.
In this case, just the overdrive will get what you want, no need to change axle ratio aswell.
Could look into the late Model F150 3+1 overdrive there's talk about on here. This will give you floor change, with shifter in the right place, and overdrive.
Martin.

blucar · 11-23-2014, 12:02 PM

To my knowledge Ford never put an OD behind a 4 spd. quite common in the '50 and later 3spd on the tree cars and pickups. The OD units would never take the abuse that a 4spd would put on the OD.
The 4.27 axle ratio is a little low for daily use.. The F series Ford trucks through '60 generally have a 3.89 ratio. I'm not to sure about the OD axle ratios after '60.

Bob C · 11-23-2014, 12:02 PM

The F150 trans wouldn't be to bad a swap beings you already have
the hogs head you could take off your 4-speed to use as an adapter.
A 49-early 51 Mercury overdrive trans is another choice.

Bob

Charlie ny · 11-23-2014, 01:54 PM

Sponsored Links (Register now to hide all advertisements)

51 FL,
The cleanest way to go in my opinion is to use a '49 - 50 Merc OD trans.
We are presently doing this swap with a '52 F1. You must find a '50 to '52 F1
column shift ass'y ( I purchased all the parts required from Chuck Mantiglia in Conn,
Chuck has '48 to '52 truck parts stacked ). The '49 - '50 Merc trans bolts up to the
F1 just fine and the big plus is the clutch linkage falls into place. The 4 speed drive- shaft is an odd ball so I got the coreect one from Chuck ( still required shortening ).
A compatible cross member must also be fabbed.
Mac Van Pelt has all the impossible to find, elsewhere, parts to complete the
electrical side of things.
This is the second swap I've done like this and it is not a walk in the park but
it is really worthwhile. Coincidentally this present truck also has/had the non syncro
4 speed and was a pain to drive especially if you miss timed a shift.
Charlie ny
Charlie ny

11-22-2014, 08:20 PM	#1
1951Flatheader Junior Member Join Date: Nov 2014 Posts: 1	1951 ford f1 stock 4 on floor overdrive avail? Hello everyone, New to the forum. Finally got some time to start working on my 51 F1, it has the stock 4 speed non synchro tranny behind a well running 239 Flathead. I was hoping to find out If there is an option to add overdrive to the 4 Speed or if that was only available on the 3 speed trannys? It still has the 4.27 gears in the rear that I will be swapping out for a little taller set when I get the chance but an overdrive would also be nice. Without changing to a T5 or automatic. Trying to keep it close to stock but updated enough to run at highway speeds. Any information is appreciated. Thanks.

11-23-2014, 06:52 AM	#2
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: 1951 ford f1 stock 4 on floor overdrive avail? I think your best bet is the three speed overdrive out of say a mid '50's F100. This would be column change though, there are ways to convert to floor change. In this case, just the overdrive will get what you want, no need to change axle ratio aswell. Could look into the late Model F150 3+1 overdrive there's talk about on here. This will give you floor change, with shifter in the right place, and overdrive. Martin.

11-23-2014, 12:02 PM	#3
blucar Senior Member Join Date: Jul 2010 Location: Ventura, CA Posts: 2,464	Re: 1951 ford f1 stock 4 on floor overdrive avail? To my knowledge Ford never put an OD behind a 4 spd. quite common in the '50 and later 3spd on the tree cars and pickups. The OD units would never take the abuse that a 4spd would put on the OD. The 4.27 axle ratio is a little low for daily use.. The F series Ford trucks through '60 generally have a 3.89 ratio. I'm not to sure about the OD axle ratios after '60. __________________ Bill.... 36 5 win cpe

11-23-2014, 12:02 PM	#4
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 8,750	Re: 1951 ford f1 stock 4 on floor overdrive avail? The F150 trans wouldn't be to bad a swap beings you already have the hogs head you could take off your 4-speed to use as an adapter. A 49-early 51 Mercury overdrive trans is another choice. Bob

11-23-2014, 01:54 PM	#5
Charlie ny BANNED Join Date: May 2010 Posts: 3,019	Re: 1951 ford f1 stock 4 on floor overdrive avail? Sponsored Links (Register now to hide all advertisements) 51 FL, The cleanest way to go in my opinion is to use a '49 - 50 Merc OD trans. We are presently doing this swap with a '52 F1. You must find a '50 to '52 F1 column shift ass'y ( I purchased all the parts required from Chuck Mantiglia in Conn, Chuck has '48 to '52 truck parts stacked ). The '49 - '50 Merc trans bolts up to the F1 just fine and the big plus is the clutch linkage falls into place. The 4 speed drive- shaft is an odd ball so I got the coreect one from Chuck ( still required shortening ). A compatible cross member must also be fabbed. Mac Van Pelt has all the impossible to find, elsewhere, parts to complete the electrical side of things. This is the second swap I've done like this and it is not a walk in the park but it is really worthwhile. Coincidentally this present truck also has/had the non syncro 4 speed and was a pain to drive especially if you miss timed a shift. Charlie ny Charlie ny