Technical Is there an open drive conversion that keeps the stock 1940 Ford Transmission?

Is there a way to run a open drive rear with the stock 1940 side shift transmission? I'm not aware of any but was hoping i was wrong. Thanks

 

i believe you can use `46-`48 Ford pickup transmission parts to convert your `40 transmission to open drive

others here will know more

 

I think 36-3 window is correct.Seems like there are some parts for sale here or Fordbarn.

 

If you need to, Speedway has a kt that allows you to covert a banjo rear to open drive. I just saw a post on it and it looked real slick. Wasn't overly expensive either. Check them out.

 

I'm looking to keep the original engine and trans and go with a open drive rear end other than the banjo so I need to convert the stock trans to an open type. Converting a banjo to open doesn't solve my problem.

 

You can use the tail housing and main shaft off of a '42 to '52 pickup, but the mount is different, would require some fabrication to make the change. If you could find a '51-'52 pickup trans, they are side shift.

 

What Marty said ^^^. If I recall correctly, the pickup mount is slightly longer but should be workable.

 

Just an FYI speedway used to sell the hot rod works conversion , now they started making their own , probably in China ... I've seen two that don't fit for **** on the splines... If that's the route you want to go for the rear , get it from HRW !

The info on the 42-47 frock trans is correct , I'm not sure on the span between the mounts but I'm sure something could be made to work with either biscuits or the truck rubber mount, I made an adaptor to the biscuits on one once .. I believe it was a 40 crossmember

 

This may be a dumb question but why not keep the original rear end. If they are properly rebuilt they don't cause problems. I believe the guys are right about the truck parts but check with Mac VanPelt, http://www.vanpeltsales.com/FH_web/flathead_home.htm He is a member here and the "go to" guy for the early transmissions.

Charlie Stephens

 

I drive my cars several thousand miles a year and I'm not talking 4 or 5 thousand, I'm talking like 12 thousand plus. Its not uncommon for me to take my hot rod on a 1000 mile trip for the weekend and the guys I travel with , well we run 75MPH+ for hours on end. If you have ever tried that in a flathead with a 3.78 gear you'll understand why I want to change it. My last Flathead, a '51 Shoebox vert, I swapped the rear to a 3.00 geared 8" and it was perfect. So I'm either going to have to swap a high winding SBC for the flat head or swap the rear end to an open drive with a much higher gear. Since adding a Parallel leaf kit to mount a new rear end will also get the rear of the car lowered as well that would be my first choice if its possible.

 

Get VanPelts transmision book or I will loan you one. Tells you how and what parts.

 

If you convert your transmission to open drive, I'm not sure the center section in the X-member has clearance for an open driveshaft. If I'm not mistaken, a 3.3X ring and pinion is available for the banjo. That gear and larger tires should get you to where you need to be.

 

There are 3.27 gears available.

 

Well this will be a bit more money but why not a good over drive, columbia? I have one and love it. My buddy has a 40 deluxe coupe with a Columbia he drives it all the time and runs 75 at about 2500 ish.

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The pickup transmission, or parts thereof, is probably the easiest way to get an open drive in your application. However, I went a slightly different route. On a '47 Coupe I did several years ago, I too wanted a later model rear end and installed the Ch***is Engineering parallel leaf kit and an 8" Ford axle ***embly. On the transmission end, I used a '50 Merc trans I had laying around ('49/'50/early '51) . That was a bolt up to the engine and I used the the '47 side cover (arms were a bit different on the Merc) to mate with stock shift rods.

The rear mount in the ch***is required modification. I drilled the rivets out of the bottom plate on the X member, same for the stock mount inside the X, and removed it too. I then fabbed a replacement mount for inside the X that accepted a conventional Ford or GM trans mount insulator that was bolted to the Merc tailhousing mount pad. Bolted the bottom plate onto the X member, had a driveshaft fabbed, replumbed the brake lines and drove it at speed with reasonable rpms.

Ray

 

Here is a picture of the truck parts you need to turn the transmission into open drive. Plus of course drive shaft yoke. I recently sold these. Note you only need one each of the two parts.

Charlie Stephens

 

You could go one step further and eliminate the vulnerable original 3 speed box ,,using a 3 speed 60s mustang type transmission ,,easily adapted to the flathead and already open drive ,,adapt the linkages to the original 40 column ,,very strong unit ,,,

 

Hey Mike,

You could do what I did and use an early Ford to Chevy transmission adapter, and stick a Saginaw behind it. You have 4 choices of 1st and 2nd gear ratios with the Saginaw, and you get a sync'd 1st gear. I was cheap and used a Speedy Bill version that uses the stock style linkage, came with a new throwout bearing and sleeve. Only parts we needed to make was a throwout bearing return spring mount for the transmission, and some shifter arms to reach the shift levers on the transmission. I actually will redo the shift levers to clock them forward, eventually, to make it shift a bit easier.

I'm running 2.79 gears in my rear axle, and used the 3 line Saginaw. First gear is a 3.5 ratio, Second is 1.89.

 

x2. I drive my flathead '40 with a Columbia at 70+ with no problem. Other options are the Mitchell OD kit, or a 3.54 rear end. IMHO, all seem like less h***le than converting to open drive.

 

Russco; I just changed an Open drive gear box to closed and have all the take out parts. I don't have the slip yoke for the drive shaft but they are the same as a Power glide. So I've been told many times. Yes you can do exactly what you asked in your opening question. It's no big deal. If interested in my parts send me a PM.
The Wizzard

 

Or, you could get a '49-'51 Merc overdrive trans which is already open driveline plus it's a direct bolt-up to the engine. Kill 3 birds with one rock.

 

Here is a photo of both the late '40s truck 3 speed, Merc. O.D. or all three if you count the '49 Merc. three speed with floor shift linkage on the left.

 

Having installed a Merc 3 speed (see post# 15), I believe the O/D version will not fit in the X member.

Ray

 

Thanks for all the replies. There sure are more options than I realized. I will have to do some figuring and try to make a decision.
Brett on the Saginaw swap, how well does the original clutch and shift linkage work out? I want to keep the column shift, but it must work nice and smooth otherwise its a no go, same with the original clutch linkage. The Columbia is a cool option but I looked around online and didn't see any nice rebuilt ones for a '40 for sale anywhere, and I'm betting cost wise I can put a nice 8" or 9" in there WITH the Parallel leaf kit for the same money or less. I'm going to have to do some more research and come up with a plan. Thanks for all the info fellas once again this place comes through.

 

Russco,

On a traditional sight, this may not be the most popular answer, but personally, I'd convert the rear to an open driveline and hide an S-10 five speed. You not only get the advantage of the over drive, but a much larger advantage in a deeper first gear, plus far better spacing through the other three. Basically, it means your engine never falls out of it's torque band, and doesn't have to "start over" each time it's shifted. Shifter comes out at pretty close to the right place to mimic a top shift Ford trans, too.

Frank Oddo wrote something about 35 years ago I have never forgot... "Nostalgia Stops At The Firewall"! He was a hard core flathead guy, and already championing better gearing.

 

Mike,

The only issue that I have, at this point, is the shifter arms on the transmission. They need to be clocked forward, at a 90 degree angle to the shift rods. Mine are currently pointed directly down, so shifting into 1st and 3rd is currently a little clunky, since it p***es into an overextended position. Once they are clocked right, I think it'll be totally fine.

My application was behind a SBC, with an early Ford adapter, to the early Ford to Chevy transmission adapter, so I was concerned about the clutch and pressure plate setup. I wound up using a Chevy diaphram style pressure plate and took about 1/8" off the fingers to clear the sleeve that allows the use of the early Ford throwout bearing. If you are running it behind a flathead, you should be able to use the flathead pressure plate with a Chevy clutch disc. Also, the Powerglide to early Ford adapter that I used is 3/8" deeper than the Speedway or Offenhauser Chevy to early Ford adapter, so I had to use a long pilot bushing.

One thing that I learned, from years of driving the F100 with the 3 on the tree, is to use a palm down pushing action to make that shift from 1st to 2nd. Helps keep from accidentally hitting reverse and pushes the lever down to hit second. Second to third also palm down, pulling it into 3rd.

 

Russco I wanted to say congratulations on the feature of your 40 coupe in Rod and Kulture! I realize you just want to convert your ****** to open drive. Looks like the guys have given you a good plan for that. As to the 49 Mercury OD conversion some have mentioned I did that on my 40 coupe.Although the end result works well it is a lot of work to get it to fit the cross-member. I run a 3.89 9 inch rear and she will cruise at 70 under 3000 RPM.

 

I agree with you on the 5 speed trans, I actually have a Tremec TKO600 in my '40 coupe now. The car I'm asking about on this I want to retain the column shift. I'm not concerned about performance just highway cruisability (is that a word?) and keeping the original Column shift.

 

Thanks I was surprised how nice of a write up they gave it. (thanks Spike Kilmer for that)

I know that trans mount area under there isnt very friendly when trying to put a larger trans in there. I learned that lesson on my blue 40 putting the Tremec in there. I sure like the idea about using the newer fully synchronized Saginaw while retaining the stock clutch and column shift linkages.

 

I've been following this and think I see your vision and also understand what you'd like to end up with. With that said have you thought of using the GM 883 gear box? You can column shift the 4 forward gears and a simple out of view cable will work reverse. That will give you overdrive, bolt to a cheep (speedway) adapter keeping your stock clutch linkage and fit in the 40 X member. When looking in the window nobody will know.
The Wizzard