Farmall and W6 Bull Gears

Before I commit to another goofy project, I thought it best to check into a few things.

The short version of the story is; a fellow wants me to swap the transmission, crown and pinion, bull gears and differential from a '47 Farmall M into a '41 W6.

Does anyone know if it has it been done before, if not, is it possible?

With the taller wheels on a Farmall I assume the gearing must be different to provide for similar ground speeds between the two tractors. Is the difference in the transmission gears or the rear end, i.e. crown and pinion and bull gears?

You only change the transmission main shaft w/integral differential pinion and the differential ring gear. I suppose that might be the "crown" gear but I haven't seen that nomenclature before.

This will slow the W-6 down. How much? I dunno. You have to know the tooth count on both sets then do the math.

Nothing else will change the ratio except planetaries from a 660. Send us pictures when you get that done.

Or sell the W-6 and get a SW6TA or W400-450. Low range will slow each gear by 33%.

If you just want to slow down first, get a 'Low-Low' first gear set. They are kind of scarce.

If you want to roto-till turf, you will probably need the low-low, the Farmall gear set, and the planetaries. Or stretch the tractor and install an additional transmission. There were about 20 of those tractors for sale in SoCal a few years ago.

A close approximation of the change in speed will be the % difference in the circumference of the rear tires. What is the intended tractor going to be doing? Wardner has good ideas as well. Jim

Thanks Wardner, I think 'crown and pinion' is more of a slang term, bevel pinion and bevel gear, or ring and pinion are usually the technical terms used in service manuals etc. In my TD9 service manual they are refered to as the bevel pinion shaft and bevel gear. Dad always refered to a V8 engine intake manifold as 'the battleship'. I never heard it called an intake manifold until first year tech school.

The tractors both belong to a fellow who wants to make one out of the two. He has one of each. The M has a good engine and drive train, but the rear end housing is busted out under a bull gear. The W6 has a good engine and all the transmission gears including the lower shaft, but the main shaft and everything else is gone. He told me why, but I can't remember.

He was hoping we could use the parts from the M that are missing from the W6, including the bull gears. I told him there may not be enough clearance in the rear end for the Farmall bull gears, if they are of larger diameter that what the W6 had.

He's going to do all the 'tearing apart' so I quess we can take some measurements and teeth counting then go from there.

Could be a fun project. Dad had a reputation for taking on these type of jobs. Maybe some folks think it's hereditary.

I think (but am not certain) that the gear sets are different between the two transmissions. Numbers of teeth and details of shifting forks. Be careful not to make it a disaster. Part numbers can be found in the caseih.com parts diagrams on line. Jim

If the W6 and M are the same year tractor or near, the trans. and rear housings will be the same. Most others work. You can do what you want with the right parts but is simpler if both tractors are not real early versions. Bull gears and pinions are the same on both. For most M and W6 tractors with standard transmission gears, use the pinion gear or main shaft from the M along with the differential. Use the M transmission gears, reverse idler and input shaft. Or you can mix some transmission gears. Since you don't have the W6 pinion you can't put the W6 set in the M. W6 standard transmission gears 1,3 and 4 are one tooth different on bottom and top than a M. Gear 1 turns the main shaft slower, 3 and 4 faster.
I put the slightly slower W6 first gear in my M. Put the W6 first and second gear on the counter shaft, first and reverse sliding gear and reverse idler gear in a M with other gears M.
Also you need to use the M axle housings and axles from the M on the W6 housing.
W6 pinion 19, ring 47. M pinion 19, ring 50. 19 tooth main shafts don't mix with the different ring gears.
Should add that W6 tractors built sometime in 1942 and older used the same speed first as a M with standard gear speeds.

Dadgummit D Slater, why couldn't you live just around the corner. I could have sent this project your way. I'll take Jims advice and see if I can fill in a few blanks with a search of caseih.com parts.

Why do the M axles and axle housings need to be used? Will the W6 fenders work with the M housings or will brackets need to be fabbed?

If we can get this project to sound complicated enough, maybe the fellow will change his mind and hunt down some W6 parts.

Guess I misunderstood, thought you just wanted a good housing for the M. If wanting to fix the W6, the ring and pinion from the M will work but slow the tractor down in all speeds. Guess since you don't have the transmission sliding gears with the 6, The M transmission gears will need swapped in. Another thing to keep in mind depending on ring and pinion used is the transmission rear main shaft bearing housing. Different for 6 and M main or pinion shafts.
No axle or housing change needed if fixing 6.

What about the pinon shaft bearing carrier,(rear) and the snap ring location between the two? Was thinking the location was different?

Yes thats what I was calling the rear bearing cage or 3 bolt housing for the pinion shaft bearing. Use a W6 one for W6 pinion and a M one for a M pinion. His W6 one is probably gone along with the pinion shaft.

Well we might be in luck then guys, because we have all the bearing and seal retainers etc.

It's going to be a while before I can get at this project because I'm working on a John Deere AR for another fellow, and at my present rate of progress, it will be well into the new year before it gets the boot.