A couple of months ago, I bought a LT160 for my son. It was in good shape, had a snow blade, deck and pickup system. But, at almost 400 hours, the hydro whined and it wasn't able to backup some of the steeper parts of his lawn. Changing the oil did not fix the problem.
After reading all the trials and tribulations about the smaller Tuff-Torq transaxles, we started watching CL because the $1000+ K66 conversion kit was a bit more than he was willing to spend. After a week or so on CL, I found a Simplicity Broadmoor with a bad engine and less than 400 hours. I contacted the seller who confirmed that this tractor did have the Tuff-Torq K61 so I paid the $150 asking price and brought it home.
I had already looked at pictures of the K61, K46 and K66. Based on those pictures, it appeared that the K61 could also be installed in the LT160.
Here's the final result.
The K61 is under here.
Tire and wheel size - The K46 had 3/4" axles, the K61 has 1" axles - both tractors had the same size tires, so all that was needed was to paint the wheels yellow.
Bolting the transaxle under the frame - The mounts on the axle matched, so no changes needed to be done there, but the forward support was in a different place, so I had to modify one of the existing supports and drill a new hole in it.
Connecting the drive belt - the K61 has a pulley that is almost 2" larger in diameter than the K46 and it is farther forward on the trans. The LT160 drive belt was 91" long, the new one is 89" The new belt just touches one of the supports for the tensioner, I don't like the idea of the belt rubbing, but if it were 1/8" farther away it wouldn't touch. The rubbing is in the middle of a long run, so there isn't much tension on it. I'm going to leave it for now.
Attaching the forward/reverse lever. Both transaxles have the control on the right side of the trans and operate in the same direction. The throw length is different and the K61 has a horizontal throw while the lever on the K46 is vertical. I had to trim the length of the K61 lever, notch the frame on the tractor to allow room for the dampener and drill a new hole so the connector rod would allow the lever to move properly.
Attaching the brake. The brake on the K46 is on the far left side of the transaxle, the K61 has it more centered and about 6 inches farther back. I had to build a support for the LT160 brake rod and fashion an extension using one of the pieces from the other trans. After adjusting the brake, it has the same feel, but since the hydros tend to stop and not move when in neutral, I'm not certain that the brake on the trans actually works. Everything is connected and moves like it's supposed to.
Attaching the fan - The K61 fan interfered with the LT160 frame, so I bought longer bolts and put 1/2" spacers between the fan and the pulley. The K46 had a smaller fan that was below the pulley, the K61 has a larger fan that is above the pulley. I had to move the reverse switch wire out of the way, but other than that there is no interference.
Operating the release lever - The release lever on the K61 is in the front of the transaxle; the K46 lever is also in the front, but it has the rod bend around the trans and come out the rear of the tractor. I wasn't able to build a release lever that had the proper bends in it, so to release this trans, one has to reach under the tractor and pull the lever forward manually to release it.
Filling it with oil - The K61 has a plastic reservoir that holds a couple of ounces of oil and allows one to see that it is still full. The LT160 mounts the fuel tank directly over the top of the filler. I remvoed the reservoir and used a 3/4" chair tip to cover the filler, but filling the transaxle is problematic. It can be done using a funnel with a tube more than two feet long, the tube has to be snaked inside the frame near the front of the left rear tire and held in place while oil is poured into the funnel. The only way to tell if the trans is full is by watching for the oil to overflow. I need to find a rubber 3/4" right angle adapter that will allow a hose connection so the trans can be filled without overflowing. We filled the transaxle with oil before mounting it under the tractor, so we've only topped it off once, I think it will be ok.
When we started the engine, it took nearly 20 minutes before the wheels finally started turning. After another few minutes of light movement, it got to where it's working well. We hooked up his 5'x8' trailer and moved it around. Before we pronounced it working, we put some wheel spin marks in his turf trying to back the trailer up a hill with me on the tractor and him on the tongue of the trailer right behind me. The K46 would simply have stalled doing that. With him on the trailer, it will also pull some very impressive wheelies when starting out quickly.
This project is a success in that he has a working tractor again. However, I can say with some certainty that the K61 transaxle does not fit the LT160, I don't recommend it as a replacement. It works, but it certainly isn't a bolt in replacement.