TuffTorq K46 Repair Guide with Pictures

[tntatro]

I got the transmission back on the mower today and it seems to work good now. The problem had nothing to do with the dump valve pin. I could tell from the wear marks on one of the surfaces on the center block that I didn't flatten it well enough. The block I used to flatten it had a low spot in the middle so I ended up making it lower towards the center where all the pressure is. I found a better technique for surfacing the center block by first flattening the motor block on a surface plate with sandpaper, then I glued sand paper onto the motor block surface that I flattened using a medium strength spray adhesive and put the splined shaft through it and into the center block the way it goes together when assembled. That held it in place so I could just rotate the motor block and flatten the surface of the center block. I covered the surface with marker to measure the progress. The other side looked okay so I didn't do it but I think the same technique could be used on the other block as well by removing the shaft from the case and doing the same process. The glue is easily cleaned off with Wd40 or PB blaster. I used 400 grit paper and finished with 600 grit. If I were to do it again I think I would polish the surfaces with finer paper. I'll have the owner let me know how it holds up and update if there are any issues with the rebuild. If it holds up then that saves $400 in parts.

 

[tom3]

Kind of scratching my head on gluing the paper to the block, but I think I get what you were doing, matching the surfaces.

 

[tntatro]

Yes, just matching the surfaces. I cut a square out of sand paper and sprayed adhesive on the back and put the block on it and let it dry for a few minutes then cut the excess off and cut a hole in the center for the shaft. The first time I used the piston side of the motor block without putting the shaft through it and just sanded in a circular motion but I didn't realize the block was slightly raised in the center and that sanded more out of the center.

 

[tntatro]

The owner of the mower is happy with it but I don't think it works like new. I probably should have done the other surfaces again using the better method. My main concern is that it might create fine shavings from the uneven surfaces. I'm going to have him mow a few hours then I'll drain the oil and maybe put in synthetic 20w-50. His transmission had the magnet upgrade so hopefully any metal gets picked up. If I do have to do it again I'm pretty sure I can get it going even better. I don't know how it was when new but I thought it would drive a little faster and climb a little stronger, although it does climb hills even with the lever halfway and if you push it all the way it will speed up. When it's all the way up it will move back a little when going uphill if you don't hold it in place. I might be able to fix that by tightening the spring on the linkage.

 

[stevem5215]

K46's aren't the most powerful transmission even when new. They are adequate for flat surfaces and on hills it's just not like a more powerful version of a Hydrostat trans. I have 3 here. A K46 Black Craftsman 24hp a ZT2800 based ZTR Simplicity and a ZT3400 based ZTR Simplicity. The best is the ZT3400 transmission. It is a great transmission. The other two are lesser. And you can notice that less ness when going up hills.

 

[tntatro]

Yeah, maybe that's pretty much all it has for climbing ability. I was surprised at how small the transmission is for the size of the mower. I could carry it under one arm.

 

[molarski]

Hey guys, I have K46 trans, for me the loss of power happened rather rapidly. I was wondering if there is anything inside center case that could be broken as I was trying to flatten its surfaces and the revolvers like 4 times but unsuccessfully. I am loosing my mind with this trans. Does anyone have any spec for the diameters of the revolver small cylinders? They are rather tight in here but would like to compare to the new ones. Already changed the belt, not sure what else can be wrong there. Thanks in advance.

 

[Kyle_in_Tex]

just to keep this thread going. I have ordered a rebuild kit. I guess i could have sanded it down, but after 375 hours this mower really doesn't owe me anything. I've only ever changed belts on it. Mow 2 acres, once or twice a week for 11 years. Started getting bad after i dragged a harrow around for a while landscaping the front yard. Right after that the power was never the same and over the 3 years after that landscaping it was a struggle up any incline and it was hit and miss for power. If it was hot out forget it, the thing was like a turtle. Fall and spring were okay. I changed out to a heavier gear oil last week to see if i could salvage it, but it just made more noise than it ever did. Hoping this $450US dollar fix kit works. Here's some photos of what i pulled apart.

Did your kit help it out?

 

[nicnac117]

Dont recall seeing it in the previous 103 pages . My lower case has been milled by the intermediate gear outer side . I think P901,s shims would stop this from happening

 

[stevem5215]

Well, the K46 in my 2009 Black Craftsman Professional quit working again. This time though it had broken off the two mounting bolts from the cross frame member to the K46. And dropped the belt and popped off the fan ! I pulled the transmission out today and easy outed the two bolts (one was rusty and broken for quite a while it looked) the other had the old bolt laying on top of the mower deck. I drilled them and easy outed the studs and bought new Grade 8 bolts and cut them to size and cleaned up the holes. I cleaned up the transmission asm (it was pretty filthy oily and dusty oil encased on the housing). Drained out the oil (the last time I worked on this was back in 2011). This time there was no synthetic 5w-50 available so I used 5w-40 Euro spec. Fixed all the bent pieces on the frame and put her all back together. Changed the engine oil and filter and fuel filter while I was at it. Works like new again. Now it needs a bath and some wax on the metal and back to sleep till spring ! Another K46 still operational.