Case 580k Bull Gear Final Drive Repair

[580meyer]

Hello All,

I have a case 580k backhoe. I just replaced both final drive gears. (1 was broke and the other had cracks) Took everything apart kept everything clean reassembled the transaxle and now have an issue. It appears 1 of the drive gears is very tight to the bull gear. As I slowly rotate the tire i can feel resistance every few inches of rotation. When I rotate the wheel and look into the top inspection hole the resistance matches the rotation of the final drive gear. It looks like everytime a final drive gear tooth hits top center on the bull gear there is resistance. It is almost like the teeth on the new drive gear is a couple thou thicker than they should be. Has anyone ever run into this? Any suggestions?

Thanks for any ideas!

 

[alrman]

Congratulations on your first post @580meyer

I wouldn't think there is a problem with the gears.... (famous last words ) I have replaced quite a few over the years, using genuine bull pinions (side gears) & non-genuine, & never had an issue.

Did the shim packs for each side go back exactly as they came out? Keeping LHS & RHS seperate?

The thrust washers between the bullpinions & the crownwheel carrier are different thicknesses, to allow correct clearance with the hemispere/spider gears - were they kept in same location - LH & RH?

Did the bearing preload get checked for the bull pinion gears while they were both installed? (rolling torque 4-8 pound feet)

Were the old bearings for the bull pinions used or replaced? Were they properly seated when fitted?

Has the crownwheel & pinion clearance been checked in multiple places? (.006" - .011")

Has this transaxle got the park brake disc on the front of the transmission? If so, they can get a wobble on them & create what you have described above - be sure it is not dragging on the brake pads.

 

[580meyer]

Thanks for the reply Alrman,

So I kept the shims on the same sides as they originally were. There was .040" on the left and .050" on the right.

Same goes for the thrust washers. Never measured them but kept them on the same sides.
I did not replace any bearings. I inspected them well and they seemed fine. I did however have to take the 2 bearings off and place them on the new bull pinions. Yes they were seated down as far as they would go. When I bolted it back together it snugged right up, but I could still turn the bull pinion. I never checked the rolling torque. I just kept turning it by hand and could feel the resistance when the brake housing was tight. I can turn it by hand but it would never free spin.

I checked the crown wheel and pinion the best I could and it seemed to measure consistently around .008"

As far as the castle nut on the bull gear I tried it tight and loose (maybe 1 full turn back) and it doesn't seem to make a bit of difference.

I had placed a piece of clay on the bull gears and rotated it through the pinion gear. On 1 side it left a very thin film of clay on the bull gear. I couldn't measure it but i could see a faint film. On the other side it hits so hard that there is no film left.

The parking brake is on the front of the trans. I will check that.

My concern is when I rotate the tire by hand I can feel it on 1 side. not bad but its there. I am half thinking about just using it and seeing if it soothes out, but i think that might be a bad idea.