No. 9 mower gearbox

[Rivendell Farm]

My No. 9 mower has an oil leak around the clutch shaft and I was wondering if it’s worth the trouble of replacing the oil seal there. How difficult is it? Does the mower axle need to be removed first? Is there a bushing there that also should be replaced? Because the original recommendation was for a lighter oil in the gearbox than the 80w90 gear oil I’ve always used, I am considering trying a lighter synthetic gear oil used in semi-tractor transmissions to reduce draft. I don’t want it all to run out past the clutch shaft. Any opinions from the mower re-builders out there?

Bob

[Stone Horse Farm]

I’ve done it. I had to pull the gears out to get to the shaft and the seal. Seemed worth it, and wasn’t too difficult. Didn’t have to pull the axle. With the gears out you can really clean out the bottom of the box too. If you put a lighter grade of oil, it will run out of the old seal. The lighter grade will help the horses, though.

Stu

[Rivendell Farm]

I found it was possible to pry out the oil seal without removing the shaft. An Amish neighbor who rebuilds a lot of mowers told me you can simply “pop it out”. Popping out took probably an hour with a lot of mutilation of the old seal, but it did work. I’ve put a 50 weight synthetic oil in and so far none has dripped out. Of course it is winter and the mower is just sitting. Bob

[Jay]

I also have removed the seal- easiest to just take the gears out (not the big gear on the axle, just the smaller ones and the clutch). Look at them carefully as you take it apart so you can get all the shims, etc. back together in the right order. It’s then fairly simple to take the shaft out and pull the seal and well worth doing in my experience. Jay

[Does’ Leap]

Ditto on the above comments. I’ve done it. Not a bad job and well worth the effort. I think I put two seals on there for good measure. To add to Jay’s suggestion, I snapped a half dozen pictures of the gear assembly as I was taking it apart to refer back to during the reassembly.

Good luck.

George

[Author]

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