Tuff Torq K66 Hydrostatic Transaxle Rebuild - Part 1

[@NathanielGalvan]

Almost 10 years later and I'm doing the exact same process on a K66AG out of a husqvarna GT48XLSi - I don't know you postman, but you have saved my bacon with these videos. My deepest thanks to you and your camera man for the great information and camera angles.

[@bwhited2]

Any luck? I’m getting ready to tackle mine on the GT48XLSI.

[@NathanielGalvan]

@bwhited2 yep! Went smooth as butter. A couple of tips: 1. On the husqie the rear end is inaccessible when it's in the mower. When you're bleeding the system after it's back in, I was able to snake an air hose I ripped from a bicycle pump to the overflow tank and put the oil in a measuring cup and siphoned it down to the Trans. I'm sure you could do it easier with a funnell, but I didn't have one that would fit the piece of air hose I had on hand. I was also able to get a lot of the air out by putting a power drill with a socket on the bolt for the fan and spinning it for a few minutes before I reinstalled the transaxle. It really didn't need much after I filled it til the overflow tank was completely full. Once the system was bled it worked out to just about right. 2. The fan blades are pretty flexible, so don't be scared of muscling them out from around the belt 3. The diff lock didn't change the process. It's activated with a lever that's held down with a tab bolted down on the outside of the housing. You can leave it in place, the linkage connecting it to the switch is a little tricky, if youre forgetful like me then take some pictures before you take it apart. 4. The almighty pin and washer for the pump/motor disconnect stayed in place really well with a little grease while I tried to get the center case seated. That was the most finicky part. At one point it looked like it was seated, but after looking at the brake disc, i realized it wasn't quite there yet. Definitely take extra care on that part. 5. In the video, postman puts the sealant around the upper case housing. I would recommend putting it on the lower case housing (the one thats empty during the rebuild process) instead. There's little voids cut in that side that are supposed to be filled with sealant.

[@bwhited2]

Thanks for the info, may I ask why you took your transaxle down? We’re you able to find parts? Mine is a little noisy and won’t pull once it’s warm.

[@NathanielGalvan]

@bwhited2 that's exactly the issue I had. It would run for 20-30 minutes on flat ground, but once it got warm it would slip and make noise. I called Tuff Torq directly to get the SKU I needed to order for the repair kit on their site. They asked for the serial # printed on the transaxle, you can see it from the back of the mower, it's printed on a sticker. I will say, while customer support was helpful, their site was awful, I never got an order or tracking number, it just appeared on my door step after two weeks of calling customer support and getting told it got sent to a warehouse that didn't have it in stock. There are people that sell the same kit on Amazon and eBay, not sure if that's a better route but oh well. Either way, I got what I needed in the end, and customer support did all they could for me which was appreciated. The kit cost something in the neighborhood of $450

[@bwhited2]

Thanks again, I appreciate your time and help, I ordered a repair kit for mine today. Looks like I’ll be tackling it soon.

[@davebenedict7986]

Thank you for sharing/posting. The pin you discovered that kept the center case from being removed is what drives the charge pump. The charge pump feeds the main pump, instead of just trying to draw fluid into the main pump. True, there is no pin in the main shaft of a K46, because it does not have a charge pump. A K57 does have a charge pump, and so does a K66, as you discovered here. That is also why....you can pull the main shaft straight out of a K46 or K62, and not a K57 or a K66.

[@jolierouge8332]

Gotta love the postman. Excellent video. I had the rebuild kit and tranny taking up my workbench for over a year, and it was this video that got me rolling. The project went smoothly and the machine is back in operation. As the postman said, it was $400 vs. $2400 and about 4 hours of labor. Good work.

[@joepacheco4038]

Hydrostatic trans have no seals, what seals the motor & pump are the sealing washers on the ends. Any scratches will cause it to hemorrhage internally losing pressure especially when warm. Oil will thin out. Biggest concern is keeping fluid clean. I remember when I went to school for Caterpillar on hydrostatic had to use lint free wipes when drying sealing washers that's how close the tolerances were. Good luck to anyone rebuilding, remember keep everything " CLEAN " and you will be ok

[@jolierouge8332]

My G100 failed after about 2500+ hours of real tough going (actually abuse.) Bought it new about 2002 - it was used heavily as a companion during house construction. I used it to tow a 8 ft^3 concrete mixer, Vacuum motor and cart, pulled wagons filled with dirt/mulch/rock/bags of concrete, etc to such a degree that the wagon looks like it has been stepped on. We live on a steep hill so it reliably carried all this like a trooper. I also own a Cat 289C tracked loader, so I can fully appreciate what the G100 was doing. I also used the G100 and its belly mower more like a bush hog than a lawn mower, going through about 2 sets of blades a season. I never changed the fluid, and kept the thing outdoors all year - occasionally changing the battery. The seat has more duct tape than vinyl. It failed about 2014 when I was going up a hill. Something snapped loudly and the machine immediately started to roll back. Brakes did not work. Luckily, I made it down without incident. I would have sworn that the axle or something solid in the drive train sheared completely apart. I expected the fluid to look black and filled with steel debris, etc. However, there was not even scintela of hint of damage - the fluid looked clear and pure - like baby tears with barely any evidence of steel particle debris, the gears looked sharp and true, and the shafts and train were fine. I assume that the damage was owed to failed directional valves in the block housing.

[@DMJ160]

@BKD Vickers , I have to admit. Your post is the first I have read at having an issue with switching from the 10w-30 to the 5w-50. I have a John deere L130 with the K46. It was slowing down on hills. I switched to the 5w-50 synthetic and it brought the K46 back to life. To me, synthetic oil will handle heat much better then conventional oil. That was 4 years ago at around 400 hrs. Last summer i noticed it slowing again and more noise but for first 3 years...it worked close to new after switching oil to 5w-50. Just stating my experience.

[@DMJ160]

@BKD Vickers your reply makes total sense. Thank you.

[@ronclaros]

ThePostman777: what an amazing job you've done in this 2 videos (Part 1 and Part 2 for the K66 Hydrostatic Transaxle). Thank you so much for the way you explained this!!!! Finding information on Transaxles and videos are very hard to come by, so big KUDUS to you, sir! I have a Craftsman tractor which appears to have the same transaxle: it has roughly 600 hours and has been roughly mighty slowly especially going up a hill and when going on reverse. I may adventure on doing something like this if the tractor gets worse with time.....

[@ThePostman777]

UPDATE: June 2021 - 1386 hours - still pulling hills under load like a champ.

[@buzzflood7539]

Outstanding video! Very informative. You explain everything very well. Thank you!

[@genegvahle23]

Also the k72b has the pin holding center case Down 🤔

[@michmich9826]

Bravo travail de pro !

[@donhokanson2704]

I have a John Deere LA145 that has a Tuff Torq 46 transmission that went out with about 300 hours...I then bought the rebuild kit for $400 and paid someone $200 to repair...Here I am a year and a half later with the transmission beginning to slow down again. I live on a hill and I suspect that this transmission was not made to operate in such an environment and was curious as to what The Postman 777 thought of the Tuff Torq 66 since this is the unit that comes on a Husqvarna GTH52XLS that I am looking at purchasing. At the end of the video Postman 777 says he operates his mower in hilly terrain W.Va so I am thinking this unit might be more of a workhorse that would be more appropriate yo my situation.....Sure would be nice to be a DIY'er like a lot of you other folk who have posted on this site.

[@marcb8874]

merci

[@randybeard6040]

Folks, it was Recommended that you use Straight 60 weight oil in these Transmissions--Amsoil Dominator is said to work great and keeps a great internal seal on Pump pistons and Motor Pistons--I would try this before breaking down transmission.....

[@genegvahle23]

Anyone noticed of the 2 pumps , 1 is a bit bigger than the other

[@bwhited2]

Wv hick here too!

[@dickcheddar928]

what type of fluid goes in the k66a....there's two filler ports but what fluid goes where???....please help

[@Thedbcox]

Great Video, Thanks. I'm a fellow WVian with a JD G100. Have you changed the transmission oil since the rebuild? Any video on that?

[@ThePostman777]

I have not. I've added just a few ounces to keep it topped off, but no problems. Now at 1386 hours and still pulling hills under load like a champ.

[@Nudnik1]

p o s transmission. All failing in hilly terrain here in VA also. Junk Change oil every season suck oil out put in new oil . John Deere should be ashamed. Small pump is charge pump which when weak you lose hydrostatic pressure to pistons in pump and motor. I work on Heavy equipment and build pumps.. Pistons don't have bronze shoes on pump or motor ...steel on steel..If suction screen filter gets dirty and restricts charge pump intake pump will not charge pistons . One cannot clean or change filter without disassembling entire transmission. Excellent work Thanks.

[@aprivateuser]

The K66 should last for 600+ hours, with proper maintenance. The problem is the owners never change the oil in the transaxle. The change is simple: There are two easily removed oil drain plugs in the bottom of the transaxle and an external oil reservoir. I was told the reason the owners do not change the oil is JD's Owners Manual does not indicate they should change the oil.

[@bjl1000]

Roger Daisley owners manual says transmission is factory sealed and needs no maintenance. Only maintenance suggested is purging the air.

[@darkwinter6028]

Yeah... when the transaxle wears out, just pop down to your friendly dealer and buy a new tractor! See how this works? 🤬

[@SBUBandit]

@@bjl1000 Yeah, I read that too, and then after hundreds of hours I was working on something else and noticed there are two larger bolts on the bottom. Sure enough, drain plugs

[@sonko2010]

Would you be so kind as to tell us where you got your K66 Schematic? Is there a site to download? Thanks.

[@barrytaylor8666]

sonko2010 were

[@Eugene2ndW]

Does this have locking diff? Can the oil be changed without disassembly, i.e. drain and fill plugs.?

[@mr.e7022]

My K66 has two drain plugs in the bottom.

[@crabhab]

How many hrs did you have on the machine when the trans failed? I have a 1998 Scott S2554 garden tractor and a 2002 Scotts gt2554 both have the k66 my 2002 has 350 hrs and need a pump rebuild.

[@ThePostman777]

crabhab Sorry for the late reply. It started to notice a fail around 500 hours. I tried changing to a 50 weight oil, with no help. Then to a 5W-50 synthetic, no difference. Watching KZbin gave me the courage to attempt this rebuild - which is actually very simple. The guys at Tuff-Torq are great and very helpful. Best of Luck!

[@zscater]

Hreat video. Im also from WV with a G100 that just quit pulling on inclines. Serviced the transaxle fluid and no luck. Pulled the axle out and looking to do a rebuild like you did. Who did you get parts through?

[@ThePostman777]

zscater Direct from Tuff-Torq at www.tufftorq.com/parts-service/index.html. You can call them also, they're very helpful. Best of Luck!

[@timheadrick8385]

Where did you get your parts?

[@ThePostman777]

+Tim Headrick Direct from Tuff-Torq at www.tufftorq.com/parts-service/index.html.

[@brandonprice9762]

Was this a K66R

[@DMJ160]

I believe the G100 has a K66C