One day doing some loader work, the steering started jumping around. It smelled like hydraulic fluid. I knew I had a problem, so I drove over towards the barn and shutdown. With the engine shutdown, I could hear liquid pouring. The transmission fluid was pouring out.
The seal on the rear left axle had been pushed out, and as a result all of the transmission fluid drained out. In reading forums, some people would’ve just hammered the seal back in. But I was concerned to identify what would lead to the seal coming loose, and so I decided to replace the bearings and seal with new parts. This post explains how I did that.
Here’s what the job looks like according to the diagrams and manuals, though this is skipping all of the preliminary work of draining the transmission, jacking it up, and removing the wheel:
First, acknowledge that at this point you’re committed to a hydraulic oil change. Unless you’ve recently done so, so you may as well finish draining the oil, replace the filters, and clean the strainer. I hadn’t done this since I purchased the tractor used (maintenance history unknown!), so it was a must. At this point, since I was committed to disassembling the axle, I also went ahead and removed the tire. That made removing the strainer and the left oil filter easier.
The strainer says to clean it in a solvent, which is unhelpfully vague. I chose to clean it using diesel fuel, though I see others use kerosene or even solvents frequently used for painting. I found that my strainer had some metal shavings in it, but it was only about 1 ml worth.
At this point, I replaced the two filters. The part numbers follow:
- HH660-36060 (which replaced the original 66021-36060) – HST Oil Filter, which is on the left side of the tractor
- HH670-37712 (replaced HH670-37710, 67955-37710) – Hydraulic Filter (suction), which is on the right side of the tractor
Now it was time to take the axel case off. There are 10 bolts, and they’re not all the same, so take note of which hole each came out of. For this, I chose to make a diagram, number each bolt, and then put the bolts in corresponding numbered storage containers.
After the bolts are removed, you also need to remove the subframe assembly which has additional bolts near the middle of the tractor. At this point the subframe can come off, and to keep the bolts straight it’s easiest just to put them back in their corresponding places.
Now its time to split the case. Grab your oil pan because there will be more oil. Once its underneath the seam, grab a pry bar and leverage the tabs on the top rear corner where the two cases come together. It shouldn’t take much force.
Cover the case with some plastic and take your axle case into your work bench for the next parts.
Remove the circlip.
Use a puller or bearing splitter to take the bearing off. Note that this may damage the bearing, so have a replacement part on hand.
Once the first bearing is removed, the big gear should easily slide out. A few taps on the axle to hit it out of the case should knock it fully loose and it should slide right off the other bearing.
At this point, conduct any inspections or repairs as necessary. In my case, I knew I needed to replace the seal. I also chose to replace the two bearings, and I also replaced the circlip.
Everything should easily go back together in the opposite order. There’s a bit of axial play in the assembly, which means getting the seal fully seated really needed to come last. Also, to get the last bearing back on you’ll need some help from a bearing press. I don’t have one, so instead I relied on heat: I took my new bearing and heated it with a propane torch, which made it fit partially. To get it on the rest of the way, I used a mallet and the old bearing as a guide. It took a bit of fighting but it went on in the end.
Once the assembly is ready, go back to the tractor and start prepping the differential case: dig out the old liquid gasket using a pick. Apply new gasket, which the new material would be Permatex 51813 Anaerobic Gasket Maker. The case should just slide together with ease, and then attach and torque the bolts.
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