TuffTorq K46 Repair Guide with Pictures

[buckeyefarmer]

Wow, this thread has been ongoing for over 12 years! Many good advices here.

I am asking for help on behalf of my father: Recently he (again) broke a gear inside the K46 tranny (tried to pull a tonne of gravel up a hill). He dismantled it like last time, but this time around he had to dismantle the hydraulic engine as well, as the gear this time was the one attached to the disc brake, which is on the same axle as the engine.

I found the right gear for him and he assembled it on his own. Upon starting the engine and applying pressure on the pedal ... nothing at all happened, not even a tiny movement on the wheel axle. He was pushing forward and reverse quite a few times and then turned it off.

He dismantled all of it again, and realised that the small pin that supposed to lift the washer inside the hydraulic engine was missing - the one used to disengage the drive, and was later found at the bottom of the oil sump. So, he put back the pin and put all of it back together and tried again. Still no drive at all. After reasoning with him, we realised that with the pin missing, the drive should be working - it should be the other way around: Not possible to disengage the drive. So, the drive not working was not caused by the missing pin.

He dismantled it again and realised that the washer that the pin was supposed to push was missing. He just forgot to put it back the time before. He assembled it all again - still no drive.

I watched him following an instruction video on Youtube, and I could not see him going wrong anywhere, but the guy in the video mentioned something about the by-pass valves that I did not really got my head around. Mainly because I was not there when my father explained about a filter inside one of the valves.

I have a suspect that he might have lost some tiny part, like a ball inside a valve or something, but my workload is overwhelming me, so I do not have time to go there and have a look ... for the fifth time. Bless him, being over 80 years old, with an eyesight and hearing which have seen better days - I just wish he can get it working before I have to bring my own lawn tractor there, as the jungle is taking over their lawn more and more every day.

I have moved the transmission "backwards", i.e. turned the wheel axles, first one by one, then both, to test that the differential is working, and the transmission is working all the way to the hydraulic engine. From the other end, I have turned the belt wheel to confirm that the hydraulic pump is working, and it feels exactly as I expect it to do.

Are we just too shy when it comes to bleeding the pump/engine? Should we try for longer? When the (petrol-) engine is running and the forward/reverse pedals are pressed I can hear some kind of "rotating" sound from inside the transmission. Of course one would say, because something has to rotate inside as all is connected to the transmission.

I have read that some people first disengage the engine by pulling the thin thread-like handle that moves the arm and the pin inside the engine, push the forward/reverse pedals, and then re-engage the engine again, and repeat the procedure with the pedals. Would that make any difference?

Any thoughts, suggestions, or share your own aha-moments with me? I am out of clues now.

Thanks in advance //
Magnus

If the bypass is engaged, it’s like it’s in neutral.

 

[pbbp]

Many have a strut to control the input

could you please elaborate?

 

[tom3]

Might be the damper on the shift lever as shown. Some hydros have an internal cushioning port in the hydraulic pump to smooth the shift.

 

[pbbp]

Might be the damper on the shift lever as shown. Some hydros have an internal cushioning port in the hydraulic pump to smooth the shift.

Thank you for the photo, mine does not have that.
yes, i thought those 2 small ports or balls (i forget the name) had some cushioning design, perhaps best function with a lighter weight oil?
thanks all!

 

[tntatro]

Hello, if anyone is still helping on this thread I could use some advice on a k46 rebuild I just did. The transmission appeared to be in pretty good shape internally so I just flattened the blocks on a surface plate using 600 grit wet/dry sand paper and flattened the center block surfaces also. Only one of the surfaces on the center block was scored and I had to use several pieces of paper. The other surfaces were pretty good and didn't take much at all to smooth out.
I gutted the case and cleaned everything really well and blew it out with air and also cleaned all the parts and pre oiled them. When I got it back together and installed it the mower (Husqvarna LGT2654) didn't run any better, it might even be slightly worse. I used Tuff Torq oil. The drive belt has already been changed and there seems to be sufficient tension. It drives slow and won't climb hills. The hour meter on the mower has about 460 on it. It is only used for mowing and not really steep hills but some hills. Any suggestions would be appreciated. Thanks, Tim

 

[buckeyefarmer]

Buy the new parts.

 

[Engineer42]

Hello, if anyone is still helping on this thread I could use some advice on a k46 rebuild I just did. The transmission appeared to be in pretty good shape internally so I just flattened the blocks on a surface plate using 600 grit wet/dry sand paper and flattened the center block surfaces also. Only one of the surfaces on the center block was scored and I had to use several pieces of paper. The other surfaces were pretty good and didn't take much at all to smooth out.
I gutted the case and cleaned everything really well and blew it out with air and also cleaned all the parts and pre oiled them. When I got it back together and installed it the mower (Husqvarna LGT2654) didn't run any better, it might even be slightly worse. I used Tuff Torq oil. The drive belt has already been changed and there seems to be sufficient tension. It drives slow and won't climb hills. The hour meter on the mower has about 460 on it. It is only used for mowing and not really steep hills but some hills. Any suggestions would be appreciated. Thanks, Tim

Seems like for about $200.00 plus shipping there is a guy in Canada that will rebuild the pumps for you after you take them out, box them up and send them to him. That may solve your problem. I didn't want to take the chance and bought a new transaxle for $700.00 and installed it two weeks ago on my 12 yr old JD D-140 with 600hrs. Much cheaper than the $2,900.00 to replace with a new identical mower.

 

[tntatro]

Thanks for the replies, I have seen on ebay where people are offering to rebuild the pumps. I really don't know what else they could do other than flatten them as I did unless the pistons are worn which the one I worked on seemed really good. I'm going to take it apart again tomorrow. I have a theory on what might have happened. The washer that the dump valve pin presses against has a ring worn in it, probably from that pin touching it. That part of the center block was the part that needed the most flattening also. I also flipped the washer so the worn groove was on the inside. If the specs were that close where it wore a groove, maybe me flipping the washer and sanding the surfaces made it touch and leave a slight gap. I may sand the pin down slightly and flip the washer back. Other than that I'll have to inspect the other washers to make sure I put them in the right order. The parts are $400+ dollars so I have to make sure it isn't a different problem before investing that much. It's not my mower. I'll post the results after I check it out and get it back on the mower. I think before buying the parts I'd consider having the owner get a better transmission like a k66 and modify things to make it fit if I could find good information on that. There are some good deals out there for k66's, I would just have to make sure I got something that could be made to fit.

 

[Engineer42]

To go to the k66 you have to buy new rear rims and tires, about $300 I believe. Plus the k66 is about $900.00 plus shipping. oops, correction. $2,050.00 for the complete kit.

 

[tntatro]

Yes, it's a lot if you buy new from a dealer but I see new k66"s on ebay for $400-$450 shipped, I just don't know if they would fit both mounting and linkage. I've read on other forums where people have done it by modifying things themselves but they had a different mower. The hubs would have to be switched but maybe not the wheels because this one has the 5 bolt wheels. It would still cost a lot more than the kit for the k46 but I think a lot less than a new mower the same size and he would have a garden tractor instead of a lawn tractor. he was thinking of buying a new mower but I said I would try to get his going.