Thanks to this Thread I was able to repair the LT180 I just bought at an auction. All was good until about 30 minutes of mowing when the world stopped turning and the machine was barely moving. After reading all the info above I took a slightly different approach to remedy the slow trans-axle condition. Taking the least aggressive path, I was curious if just a fluid change would make a difference, I decided to jack the rear end up and pop a couple drain holes into the Axle cast housing where Tuff-Torq suggests. Here is a Link https://www.tufftorqservices.com/EnvEEdefault/FlatHTML/TechInfo/ttcoil/pdfs/K46%20Drain%20Port%20Location.pdf I used a 1/8 stubby drill as not to injure any interior components, both holes drained over night. I then added 2 self tapping screws 1/2 inch long with a neoprene washer. Without the deck on the machine I was able to reach under the frame and pop the fill hole cover off using a stubby flat screwdriver. I cleaned up the magnet and filled the unit. 24 inches of 3/8 clear tubing and a small funnel allowed me to add back the 2 quarts of cheap 10-30 oil for my test. Popped the magnet and cap back in place and DONE! I am pleased that the result was success, the machine runs very well without growling and slowing after 30 minutes of use. My intention is to replace the 2 small drain holes with real drain plugs after about 5 hours of use and refill the unit with synthetic oil for hopefully many more years of use. Happy Mowing!!

You have the Tuff Torq K58 trans, it's a K46 with a charge pump addition. Life of a K46 is about 900 hours, slightly better for a K58 I would assume. Heat is the main destroyer of transaxles. Keeping the transaxle fins clean is a must to have it last. See the link attached for how to rebuild a K46, but it is very long (72 pages). Change the fluid may help and is cheap - use 5W50 synthetic motor oil - 2 Qts. Some have had great results just sanding out scratches on the internal parts. Here is a link that might be useful: K46 rebuild

Thanks for everyone's advice - saved me hundreds of dollars and a lot of time! After 10 years and 406 hours (with a self-installed meter) I experienced the screeching / grinding / scraping noise problem with my John Deere / Scotts S1642 riding mower whenever I engaged the transmission in forward or reverse. My mower would move slowly, but if I tried to gain any speed, the grinding noise started and the tractor stopped. As with many posters here, I discovered the cause to be extreme wear on the hydrostatic drive's input pulley and input shaft. The spline mating surfaces on the ID of the pulley and on the shaft OD had both worn so badly that the pulley could spin freely (albeit in a chattering way) on the shaft. When I was driving very slowly, the belt pressure held the pulley up against the shaft enough that friction and what was left of the teeth would turn the input shaft. At higher speeds, the torque overcame the grip between pulley and shaft and the pulley release and ground around the input shaft. I solved the problem by removing the Tuff Torq K51A transaxle (just put the rear hitch on a cinder block and a piece of 2x4, pull off the rear tires, disconnect two linkages to the tranmission, remove six bolts and it's off!), and replacing the pulley and input shaft. Total cost for new shaft kit, new oil, and a new pulley was about $100. Time to complete the repair was about 4-hours once I had all the parts. I ordered the replacement Splined Input Shaft (Part #19216899490 - called a "Pump/Bearing Kit - K51A, B, E") from Derrick at Tuff Torq (actually I got advice from Derrick - Phone: 866-572-3441, and ordered the parts from their web site - www.tufftorqparts.com - The Input Shaft Kit consists of a splined shaft, a seal, and a spring [the spring is a new improvement and was not part of my original K51A.] The kit cost me $25.00 plus shipping.) The replacement Pulley (#M127358) I got from my local John Deere Dealer for about $15.00. Replacement of the Input Shaft is easy and is accomplished without opening the case! While working on the transaxle, I took others' advice and replaced the oil in the unit with Castrol 5W50 Synthetic Oil. On Derrick's recommendation, I just popped the big oil cap off, removed the spring and filter, then inverted the K51A on a 5-gallon bucket to drain. NOTE: Derrick says to NOT invert or move the K51A while you have the input shaft removed as components inside can shift! I drained mine before changing the shaft. Changed the shaft, then filled with 2.25 L of 5W50 (should fill to just above the filter.) The new spring that goes on the input shaft required some fiddling to get down into the hole. Be sure to purge the air from the transaxle after refilling it with oil. I failed to do this and at first I thought my repair had failed. Instructions for purging air can be found at the Tuff Torq link above - under the Tech Info link in the lower left corner. After I drove the mower in a slow, herky-jerky fashion for a few minutes, things smoothed out and now it runs as good as new. Now that it's purged I will recheck my transmission oil level this weekend.

my2014 X300 transmission just died.,.,,.230 hrs on it.,.,i mow approx. 1.2 acres and use the 44 inch snowblower.,.,.,i was told by dealer that J.d new of this transmission issue early on and then rebuilt/redesigned the tranny in the newer versions in 2018.,.,realizing that the 3/4 axles were borderline strong enough for the snowblower attachment.,.,.,$1,200 later.,.,i'm mowing again.,.,,.if your going to add attachment to any tractor maybe 3/4 axle should be avoided.,