Re: A couple of transmission questions

Sun Jan 06, 2013 1:00 pm

Agree with Boss. Do you have a 'Service Manual'?? It is invaluable, especially for something like this, Generally the shims stay with the case and which sides the differential carrier shims came FROM is important. The ring and pinion gears are a matched set.

The only thing easy about getting it right is reading about it :roll:. Try a search. This is a good write up on the differential.

viewtopic.php?f=1&t=50301

Re: A couple of transmission questions

Sun Jan 06, 2013 1:05 pm

Yes - you really want to get the backlash down closer to the 0.003/0.005 that the book calls for. It won't hurt the gears.

Re: A couple of transmission questions

Sun Jan 06, 2013 1:34 pm

Buzzard Wing wrote:Agree with Boss. Do you have a 'Service Manual'?? It is invaluable, especially for something like this, Generally the shims stay with the case and which sides the differential carrier shims came FROM is important. The ring and pinion gears are a matched set.

The only thing easy about getting it right is reading about it :roll:. Try a search. This is a good write up on the differential.

viewtopic.php?f=1&t=50301

I have the manual. I am putting the guts from my transmission into a "new" case so preload and shim placement start from.scratch. I can get the backlash closer, but those gears sure are loud when I get there.

Re: A couple of transmission questions

Sun Jan 06, 2013 8:25 pm

High jacking this thread bit a related question. I have replaced the differential bearing cones and adjusted the pre load. Is there a need to check the backlash if there was no change?
Wally

Re: A couple of transmission questions

Sun Jan 06, 2013 8:28 pm

How did you adjust the preload?

Re: A couple of transmission questions

Sun Jan 06, 2013 8:38 pm

Using a fish scale as they show in the manual. That was no easy task. I had a nice digital fish scale but cant seem to find it so I figured I would pick up one of the old Zebco's. No where to be found. Finally found a cheep one at Bass Pro. . I then torqued the caps with shims till it felt like there was some resistance and put the scale on it. It was right where it should be according to the book.

Re: A couple of transmission questions

Sun Jan 06, 2013 8:41 pm

wfmdfm wrote:High jacking this thread bit a related question. I have replaced the differential bearing cones and adjusted the pre load. Is there a need to check the backlash if there was no change?
Wally

Did you put the original shims back in the same location? Bearings are precise. Castings are not. If you kept the same shims in the same location you should be OK as you are really shimming the casting variations, not the bearing variations.

Re: A couple of transmission questions

Sun Jan 06, 2013 8:43 pm

Just to throw another question into this interesting thread, Why did or would IH build the tranny so that when the pto is run stationary the main shaft bearing get no oil? Seems kinda dumb. It's turning at rpms upwards of 1600 i assume so why let them run that way? Why did they build the wide belt pto adapter if it caused the bearings to starve of oil? Seems like using the wide belt adapter would mostly be used stationary. Also does running a cub sitting still in neutral cause this same scenario?

Re: A couple of transmission questions

Sun Jan 06, 2013 9:20 pm

Chris D wrote: Why did or would IH build the tranny so that when the pto is run stationary the main shaft bearing get no oil?

Also does running a cub sitting still in neutral cause this same scenario?

That is the same scenario.

Re: A couple of transmission questions

Sun Jan 06, 2013 10:48 pm

I bet most Cubs don't get proper lube to those bearings, the oil 'feeds' in the castings are very often plugged. Not to mention it is not unusual to have water in the tranny. Water is bad news to bearings. But still an outright failure is pretty rare considering the abuse they get.

This whole procedure is tedious and time consuming. The short story is the differential bearing preload (1 to 8#) is set with an EMPTY case (the retainer bolts should be torqued to 45 ft#). The original shims for the case probably are correct. The side they came off of are important as that 'sets' the ring gear position left to right (against the pinion). You can move shims side to side after the preload is set to adjust the mesh/backlash. AFTER you set the preload, you need to remove the ring gear. (I still can't do that without removing the right bearing, but rumor is it can be done). Then install the countershaft with gears, shims and bearing carrier.

At that point you can adjust the backlash/mesh, essentially moving shims side to side and adding or removing countershaft shims.

One day I will get a dial indicator with a magnetic base....

Re: A couple of transmission questions

Sun Jan 06, 2013 11:13 pm

Buzzard Wing wrote:(I still can't do that without removing the right bearing, but rumor is it can be done).

Yes...it can be done. I have done it at least 4 times in the past couple of weeks. You have to get it just right to remove it, but once the carrier is in the right position, it will slip right out. :D
Having said that, you really cant go wrong following the service manual. I found that I had to add a .004 shim (which I made from sheet shim stock) to get the bearing preload within the 1-8 lbs pull.....difference in the casting from old case to new case.