MD tranny teardown

Since finding the gear with the missing tooth, I have no choice but to take trans. apart. This, after it's all nicely painted up. Oh well, can't run it like it is. I did locate a new (used) constant mesh gear. As I see it, it's a lot of dissassembly and then removal of top cover and also taking out clutch shaft, and proceeding from there. I've never attempted this, but it's necessary if I'm going to use the tractor. Any one having any tips on dissassembly, your comments are appreciated. Also, if you want to help, I'm in eastern NY.

Post some pictures of the process when you tear into it. I have split tractors to do clutch and TA work, but never took a transmission apart. I'd like to see how it is done.

Good luck,

CT

Block up the fuel tank to avoid removing it!
Take pictues of each step from different angles.
Put bolts in holes in a piece of cardboard to be able to put them back in the same hole.
Take the clutch plate (6) bolts loose not out, to remove the clutch shaft.
Put a gag under the center bearing (where 4th -fifth gear is located to catch the rollers located there (SEE diagram on line)
Use a skim of Blue RTV for a top gasket. Replace the top shaft seal while it is apart.
Make sure the forks go back on the gears!!
Jim

It's not hard at all. Like you said there are about 9 million things you have to take off just to get the lid off. Here's hoping you don't need the torch at all. :shock: Some of those lid bolts can rust and break off or just be REALLY tight.

Use the shop crane (somehow) or a buddy to get the lid off bc you have to go straight up with it so you don't bend the shift forks. The crane would also help you set it down easily while aligning the shift forks. It is really a three man deal to put it back on, but I did it with two.

There is nothing tricky or easy to forget that I can think of once in there. IIRC there are two different constant mesh gears though. I didn't take mine apart that far. I only took the top shaft off. I moved the bottom shaft to check for bearing play and I was happy enough with that.

It will look something like this when you get in there.


I would check out the balls and springs that hold the shift stuff in gear. The springs like to rust apart and break. Obviously, check out the bearings and make sure none of them are bad. I am not the type to replace them "just for fun" but some are. I did replace all the seals while it was apart. You may have done this before you painted it. I would suggest a local bearing shop rather than IH if you need seals and bearings. Mine usually is half of what CNH charges.

(quoted from post at 11:51:31 03/18/11) Block up the fuel tank to avoid removing it!
Take pictues of each step from different angles.
Put bolts in holes in a piece of cardboard to be able to put them back in the same hole.
Take the clutch plate (6) bolts loose not out, to remove the clutch shaft.
Put a gag under the center bearing (where 4th -fifth gear is located to catch the rollers located there (SEE diagram on line)
Use a skim of Blue RTV for a top gasket. Replace the top shaft seal while it is apart.
Make sure the forks go back on the gears!!
Jim

Click to expand...

I like to spin the nuts back on or put the bolts right back in the holes whenever possible. Not losing them or having to worry about bad labeling. That's never happened to me...

Which clutch plate?

I may not know what I am talking about as I have never done the job. I always thought the input shaft w/constant mesh gear and belt pulley gear could come out without removing the rear frame cover. You have to remove the Liftall and clutch shaft and unbolt the transmission input bearing retainer. The input shaft and bearing should slide out and escape the tractor where the Liftall used to be.

After all, this is how it disassembles should the tractor be split at the transmission. With the Liftall out, there is plenty of room.

He means getting the pressure plate loose in order to remove the splined clutch shaft so that _then_ you can finally remove the input shaft assembly!

Although I did manage once to wriggle an input shaft out once without doing that!

At least you did catch it early! I would wager that some debris or something caught between the gears led to the broken tooth.

The transmission is simple, just heavy parts. Have someone there when you take the pressure plate loose to get the clutch shaft out. You can do it by yourself but once on a SM when I had things loose and jockying things around the input shaft got loose and landed right on my neck! I was less than pleased.

Like they said use a cherry picker to remove the top; it lets you go slow up or down and pause to check shift fork alignment when it goes back on.

Pull the cover before pulling the input shaft. With everything still assembled grab the trans mainshaft right where 4th is and wiggle it around to see if there's a lot of play in the trans pilot bearing. You don't want to put it back together and then have that thing fail on you.

If you need "normal" part numbers for the other bearings just ask as a several of us have them handy. Ebay can be a good source believe it or not. Also Steel Wheel ranch.

With the top off and the oil drained you can thoroughly clean out the inside of the trans and rear. You'll likely find little bits of trash and metal. Get a sprayer and two 5 gallon buckets. Put one under the trans drain and one under the rear drain. Fill the sprayer with diesel and go to town washing everything. The junk will settle out or you can filter through an old shirt rag and run the diesel through over and over if need be. Some will be fairly clean and some will have goopy gunk.

Like Jim said, silicone is the hot tip for the top cover.

Keep us posted on your progress!

If you put a pilot bearing in that did you find it at your local brg shop. I've got my early Super M trans apart and my local place run by old guys that can find anything, can't find that. I have not tried Case IH yet, I'm still looking for one of those half price places.

The trans pilot brng is a roller brng & delicate, put a rubber band around it to keep all the rollers in place, when you slide it back together dont try and remove it, it will just crush & not hurt to leave it in there. Also the 4th gear from the back forward appears to be ground or raked off, I remember that they were equal in tooth depth to other 3 gears. IH part # for the bearing is 69215DA, only fits M/MD.

Some suggestions, after the top is off and before removing the top transmission shaft. Slide 2 gears in mesh to lock shafts, then loosen the drive dog for the hydrualic pump. Right hand threads or the same as a regular nut. Remove PTO and parts from one side of the clutch brake pedal shaft. Shaft needs to slide out enough for one end to pass the rear of the transmission counter shaft. Good time to replace seals on the clutch brake pedal shaft if needed.
On the countershaft will be spring ring just behind the rear bearing that needs removed. Next the countershaft rear bearing is driven out of case and from the rear of shaft. If you left the drive dog nut on the front of the shaft after loosening it some, that will keep the counter shaft from trying to go back when driving bearing off. Now remove the drive dog nut, bearing retainer with seal and front bearing from shaft. Shaft can then worked out of the housing. Constant mesh and other gears are a press fit on the countershaft. All this is after the transmission input and top shaft is removed as others mentioned. Keep track of the shims at the main shaft rear bearing housing.

Many thanks for all responses. Your information and advice has helped me to tackle this project with more confidence. I'll post my progress. Thanks again.

I tried and tried to find the pilot bearing through the aftermarket but didn't have any luck. I think that one is special made to IH specs. I did not try contacting the manufacturer.

You have two options. Option A is the Dealer. Option B is Steel Wheel Ranch. Option B has the better price!

(quoted from post at 21:07:08 03/18/11) I tried and tried to find the pilot bearing through the aftermarket but didn't have any luck. I think that one is special made to IH specs. I did not try contacting the manufacturer.

You have two options. Option A is the Dealer. Option B is Steel Wheel Ranch. Option B has the better price!

Click to expand...

Which pilot bearing? PTO?

There is some confusion as to the pilot bearing. (in automotive school I was told to use the term intermediate bearing, as it is in the middle of the top shaft system, between the input shaft and the output shaft. IH calls it a Pilot bearing. Jim

The pilot brg. on the front of the main shaft (top shaft), two piece needle bearing.