40 Ford to 40 Merc rear swap
 

I currently have a 4:44 ratio in my standard coupe. I have recently aquired a complete rearend assembly from a 40 Merc with a 3:54 ratio. Was looking to putting in my Ford. Both are coupes. Could this be done? What are the differences? Any help would be appreciated.

Re: 40 Ford to 40 Merc rear swap
 

If the drive shaft lengths are the same, probably. Some early Mercury inner drive shafts are one piece with the pinion gear, and if the shaft is too long, you've got a problem altering it.

Re: 40 Ford to 40 Merc rear swap
 

if the shaft is too long, it is not a problem changing out the merc for the ford-done without getting into the hard part of the rear end. just about six bolts for torgue tube, one bolt on the bars and a pin in the solid drive shaft

Re: 40 Ford to 40 Merc rear swap
 

The 40 merc is a odd ball. The 2 i have had both had the shaft part of the pinion gear.

2 ways to make it work. Take it apart and have the pinion cut off and resplined or like i did in a hotrod turned a sleave to a press fit , cut the shaft to length and welded it together. That will make some people scream but it works

Re: 40 Ford to 40 Merc rear swap
 

What motor do you have? Most cars with that 4.44 ratio had a V-8 60. If you have a 60 still in the car, it will fall flat on it's face with a 3.54.

Re: 40 Ford to 40 Merc rear swap
 

The Ford has a sleeve, the Merc doesn't,it has a nut and a jam nut. It looks like the shafts are different lengths.

Re: 40 Ford to 40 Merc rear swap
 

I have a 53 merc motor, wish I still had the 60 though. Dad got rid of it before I was born, lol.

Re: 40 Ford to 40 Merc rear swap
 

I looked in the Ford and Mercury parts books and they show the same numbers for the drive shafts and axle shafts.

I miss read the parts book, the drive shafts are not the same.

Re: 40 Ford to 40 Merc rear swap
 

I sure would like to be able to swap the whole housing. It sounds expensive for me to have the ring and pinion replaced. I have called the local shops, they say that they can do it, but when asked if they know what a banjo rearend is they don't know what I am talking about. I just hang up.. arrrg!

Re: 40 Ford to 40 Merc rear swap
 

Best to stay away from a shop that doesnt know what they are. They are more time consuming the difficult. If you get it set up wrong it will just eat itself. I just went through it with a rear that had the pinion too deep in the ring gear and it broke most of the teeth off the pinion

Re: 40 Ford to 40 Merc rear swap
 

Guys, just curious - I thought all '40 Merc drive shafts were welded to the pinion. Yes? No?

Re: 40 Ford to 40 Merc rear swap
 

All i can say is i have had 2 and both were one piece.

When they were built at the factory, were they machined out of one piece or was the gear welded to the shaft?

Re: 40 Ford to 40 Merc rear swap
 

Like you, I've had two apart and both of those were welded. I know little about Merc stuff but remain curious...

Re: 40 Ford to 40 Merc rear swap
 

The first few years, the pinion gear was integral to the drive shaft. Somewhere in there, they changed over to the standard Ford set up. Why they did that is anyone's guess but I figure it was likely due to perceived splined coupling pin problems.

Re: 40 Ford to 40 Merc rear swap
 

Gut instinct tells me the pieces were probably welded first and machined after. But purely a guess.

Mart.

Re: 40 Ford to 40 Merc rear swap
 

have we all forgotten that mercs are 116", fords are 112" DUH on all of us

Re: 40 Ford to 40 Merc rear swap
 

I didn't forget.

Re: 40 Ford to 40 Merc rear swap
 

Yeah, after measuring the torque tube at 74 inches, its not going to work. I will just have to find someone to put a ring and pinion in it. Well does anyone need a 40 merc complete rear with 3:54 gears?

Re: 40 Ford to 40 Merc rear swap
 

If i were closer i would take it. Put a 40 torque tube on it and cut and sleave the drive shaft and right into a 40 project i have now.

Re: 40 Ford to 40 Merc rear swap
 

Just cut the driveshaft, being sure to have the end product cut where the center bearing machined space will be in the right place for a 38 to 41 Ford torque tube.

Re: 40 Ford to 40 Merc rear swap
 

If a person researches further than just the wheel base, they find that the length was all forward of the firewall. They even had an extension to mount the wishbone up in the extended location.

Whether there is a difference in actual length between the drive components of a Ford and the Mercury is unknown to me since I have no Mercury rear drive assemblies to measure. Most of us would like to know this information but only someone who had done the change could tell us for certain.

What is the difference in length between the torque tubes if any?

If the integral driveshaft/pinion gear was just done as a strength measure then they likely are the same. Using the Mercury parts of that vintage is always contingent on whether the whole package will fit a particular application. Cutting the Mercury shaft may be fruitless since there are no splines in the normal ford pinion location and the shaft diameter may be too small to cut any on there. It would be much easier to purchase a new 3.54:1 ring & pinion set.