Red neck hydrostatic transaxle repair

[geezer88 17]

I've got a 1994 Toro Wheel Horse 266-H with a K61 Trans axle.  I bought it used twenty two years ago, so most of it's use has been mine.  Five years ago, it was getting pretty sluggish.  I tried the change of oil, but that made no difference.  With nothing much to loose, I took it apart and examined the moving parts.  The gears all looked pretty good except the final drive pinion.  The hydraulic pump and motor had scoring on the surface that contacts the center block.  This scoring allows the hydraulic oil to bypass the motor or pump. 

 

So, I found a nice plate glass surface, silicon carbide sand paper, and got to work.  I used 220 at first, rotating and pushing and pulling to keep the cutting as even as possible.  When all signs of the scoring were gone in about an hour.  I used paint solvent as a lubricant.  Then I cleaned everything up and and started over with 320 grit.  I did this to both cylinders and the center block.

 

When reassembled the thing was as lively as ever.  Definitely put a grin on my face. 

 

Now, five more years of use, the little red machine is again limping along.  So, rinse and repeat.  New again.  Yippee.

 

But, there are some things I learned.  The pinion is worse than it was last time.  I think particles of pinion were the major contributor to the pump and motor scoring.  The first time, I reused the filter because it looked pretty clean, and I was right in the middle of mowing season.  This time, the filter had collapsed and wasn't doing it's job.  The new filter is much better design.  It is reinforced with metal so it won't collapse. 

 

Another lesson learned is that Toro used a special build of the K61.  If you look in the overhaul manual from TuffTorq, the motor block is oriented with the "dimples" up.  That is how I reassembled it.  Big swear word.  It ran backwards.  Got the Toro manual and it shows the motor block with "dimples" down.  Switched around it runs fine.  Like I need more practice taking that thing apart.

 

So a few lessons learned:

1.  Silicon carbide paper can be used to recondition the contacting surfaces in the motor and pump.

 

2. Take a picture of the motor/pump assembly before you take it apart to make sure you can reassemble correctly for your application.  Or mark the parts.

 

3.  Use the new style filter with metal reinforcement.

 

4.  I tried to do an in-chassis change of the motor block when it was running backwards.  Not practical.  Gravity is not your friend for some of the parts.

 

If you have an oldie and want a few more years out of it, this isn't too bad a job.

 

tom

[Pullstart 63,096]

Tom,  !  Great write up, 

[bc.gold 3,403]

Same procedure I used to recondition the valve plates on the Sundstrand hydro used in my Alice Chalmers 720. I finished up with a 1200 grit wet n dry silicone carbide paper and ended up with a supper fine polish on all the surfaces.

[953 nut 55,771]

Very well documented save there.                            Got any other tips to pass along?        Sounds like you know a thing or two about wrenching.

[Tuneup 1,433]

... and good use of the term Red Neck. Use what'cha got!