TuffTorq K46 Rebuild - Teardown

TuffTorq K46 Rebuild - Teardown

05/26/2012 - 2 COMMENTS


I have a John Deere L120 mower with a TuffTorq K46 AC transmission. There are a lot of TuffTorq transmissions in almost every brand of entry level mower on the market in the last 10 to 20 years. My AC designation is specific to my mower and serial number range. Yours will be 99% the same, just make sure you get your designation right for ordering parts.

For the cost of a box of Ziplock bags, I'm putting like minded parts in their own bags and writing on it with a marker. All the clips for the rear wheels go in a bag together as one example.


There is a keyway on the rear wheels. Looks like this shaft could use a shine up before I go back together.


Ordering of parts for future reference.


This is the top bracket over the belt which is on the TuffTorq K46 pulley. There is just the nut on the one end to remove this.


There is another bracket over the belt. Just the one bolt in the orange box will unbolt that and it will come right out.



Now there is nothing obstructing the pulley so the belt can come right off. If you go under the mower and hold open the tensioner with one hand you can easily remove the belt with the other. After a look, I don't see any reason to replace my belt even after 8 years and 360 hours.


On the other side we have this arm connected via that pin in the blue box. Take the pin out, the arm easily lifts up. Put the pin back in the arm hole so you don't lose it.


Unplug the safety switch.


The arm that goes out the rear of the L120 is attached here by just a clip. With a screwdriver you can gently push, pull and wiggle this thing off. Take the arm out, put the clip back on so you don't lose it.


There will be 2 bolts here on each side to take off. Notice the yellow stripe sticker on the far left of the picture. That is your serial number and model number tag. That is where I find mine is a TuffTorq K46 AC model. When on the TuffTorq site ordering parts, the serial number helps you get into the right parts bucket.


I happen to be tossing out an old couch so I put one of the cushions under the transmission so it could fall about 1 inch down on the cushion as I remove the remaining 2 side hanger bolts (black brackets you see here).

In the blue box, big trouble. The cooling fan lost all of it's fins. Weird thing is I never remember seeing any of them when mowing. I didn't order that from TuffTorq when I got the replacement parts. Would have been better to check that and save a shipping charge and some down time.

The red circle.. is something you won't have. One of my kids put an old pin in that hole sometime back. :-)


Take these two brackets off, as shown in Red. They go in their own bag with their bolts...


This one is the vent cap. I'm pretty sure you don't need to remove this. Since I ripped it off, I will clean it up and then put it back on. It's the other plug you want to remove.


This filler cap has really no way to get it to come out (which makes sense). I used a small chisel edge to gently get under the sides a couple times on the way around. Others use a utility knife to gently pop it out.

The red arrow points to a magnet. The magnet sits in a small washer type holder. Lift that out and wipe it up. Those go in a bag together.


I'm not a full time mechanic, so I'm not sure if this is an acceptable amount of filings and gunk or not.


Turn the transmission over, draining the oil in a pan. I didn't measure my output, but did note that it would be about the 2.x quarts expected (it wasn't dry). Once the oil is out, find a way to set it on a workspace bottom side up. Take out the ring of bolts. I was unsure if they would all be the same and it turns out the two closer to center are the longer ones. Rest are all the same.


With the bolts out, gently pry up around the edges. It doesn't take a lot of force an soon it will have a bit of a pop and apart. You're just breaking the bond of the sealant here.


This is the part we were just looking at, flipped over. Take notes on where the sealant was used so we can trace back over it to put it together with new sealant.


Uh Oh Margaret, we may be in over our heads now!

Yellow boxes is another magnet, we will take that out later.

Blue box is a piece which I'm unsure what it does, but that one is loose and can be lifted out.

Red arrow is helping us remember which end of that shaft/pin has the flat edge on it.


Red box, magnet again. Lift that out and clean it up. Again, unsure if this is an acceptable level of filings or not.



I'll go over the parts I ordered when I do the page for putting it back together. The new filter doesn't look a lot like this one. This is almost like a fiberglass mesh without much of anything appearing caught in it.


The top most gear assembly will easily lift out, just don't let it fall apart on the ground, keep it together.


The pictured assembly again. Also, noting again the flat end is up there..


This all just slides apart and goes in a bag as an assembly as soon as you get it cleaned up. I'm just wiping things down with paper towels, not using any chemical cleaners or anything special.


The two clips in Red gently lift out. From there, the axels will be able to move just to the left and right. Do one first and get that gear off the end of the axel. Note, there is another clip type thing on the inside of those gears that will fall into the case if you're not careful. It's fine if it does, you can get it back. Just noting there is a round C type clip on the big gear side of those smaller gears. Take both of those small gears off the axels.


Now this will lift out easily. Keep in mind that these gears and pins are just sitting in there, nothing to keep them from falling out. Gently lift them out and clean them up. All of this goes in a bag together.


There is one of those rounded C clips that was on the inside of the small axel gears I mentioned.


These just slide out. This whole thing is like controlled chaos. All just pins and gears that are all loose, but none of them can go anywhere so they all stay in place.


The full disassembly before I bagged it up.


Here is that thing again. Not sure what it is, but it's just sitting there lose. Take it out, then the 3 bolts holding down that unit.


So far, everything has been fairly straight forward. Now this thing pops out a bit hard and it's all kinda spring loaded into place. Should be interesting getting it back together. a few pictures of the assembly and then pull it apart.




Hopefully that's enough pictures to get all the parts back in line on the way together.


I missed taking a picture back down on the rear assembly after putting the above picture of stuff away. This is the assembly which was still down inside the axel. I brought it out and cleaned it up. This is all a fairly simple stack of stuff. The 2 pieces on the lower right don't belong to this assembly, they are the brake pads, you'll see where they are and where they go back.


So, here is another problem. This is from the 2nd to last assembly a couple pictures up. Once apart, this shaft / bearing runs through the center. This bearing runs like it's full of gravel. Far from smooth to the point where it catches and stops as I try to turn the axel inside. Another thing I need to replace. Going to see if that Plastic cooling fan and this bearing are at the John Deere Dealer.