448 Case low range quit working

[rick-from-upper-mich]

I was ripping in my garden with my 448 case and I heard a clunk, the tractor would not move in low range. I selected high and it operated well, no grinding or noise. I can't take it apart right now because I need to get the garden done. Can anyone tell me where the weak spot is so I know what to expect when I'm able to tear the rear diff apart? Is there a shear pin or something that is a common problem? The selector shifts from high to low, but low range does nothing.

 

[kencombs]

I was ripping in my garden with my 448 case and I heard a clunk, the tractor would not move in low range. I selected high and it operated well, no grinding or noise. I can't take it apart right now because I need to get the garden done. Can anyone tell me where the weak spot is so I know what to expect when I'm able to tear the rear diff apart? Is there a shear pin or something that is a common problem? The selector shifts from high to low, but low range does nothing.

Most common thing is the 4 bolts that hold the halves of the differential carrier together. They stretch, become a little loose then shear. If that is it, it really common for the it to lock up and split the case at the bottom if you continue using it.

I've never seen the low slider fail, but it is possible that the selector failed to move it fully into engagement, but you should feel something when moving the lever if that's the case.

It's odd that high range works with no noise. I'd jack it up and rotate/rock the wheels while listening for clicks or grinding before risking it.

If it's the bolts, you'll need specific bolts, high strength and size from a dealer. Or Cat has a similar bolt that is even stronger. I always replace the bolts and tack weld the halves together when I open one up.

Lots of spare parts on hand if you need them

 

[rick-from-upper-mich]

I read something about the bolts breaking the case so I quit using it and started tearing it down yesterday. When I opened it up it had watery oil and rust in the case but everything looked good. I think it was a linkage issue. The lever may have slipped over the roll pin on the shaft and if the low gear wasn't fully engaged, the resulting slack might have stopped if from engaging. The sheet metal that the lever mounts to has slotted holes to adjust the swing and I don't think it was adjusted right. I'll pressure wash it when it quits raining and when I put it back together I'll pay a lot of attention to the linkage. Thanks for the reply; Rick