m60 cub tank hydro issue

[jasonbutler]

good morning! i have a m60 tank that is a friends and i work for a very large lawncare company here in ohio ( fleet mechanic) so naturally i got designated to work on this mower. the gentleman stated that the right hand drive system meaning pump or wheel motor makes an jerking motion then smooths out upon continuing the forward motion.... i assumed it was more than likely the charge motor seal leaking or something to that nature. i have had the wheel motor completely apart and found absolutely zero signs of any abnormal wear, i then decided to take the pump out and apart and inspect it . i found the thrust bearing inside the pump had broken and caused the cradle bearing to break from debris from broken thrust bearing. so i ordered a new housing did the new seals all that good stuff.... put everything back together purged the system and the jerking motion is worse now than it was before..... also i tried to manually turn the hub by hand to see what i could feel exactly in a slower more controlled movement. it feels like it builds good fluid pressure but has a slight slip almost like the splines of the hub shaft inside the wheel motor are rounding but again the wheel motor is in new condition nothing its worn. im starting to think maybe we have a bad seal somewhere where air is getting is causing the slip almost like a pocket. has anyone ever heard of or had this issue????? i have done quite a bit of hydro work and have never seen this before and i hate to keep throwing countless dollars at this mower.....thanks guys

 

[Rivets]

Those units can be a real bear to purge. I’ve had to repurge a few 3-4 times before I got all the air out. Most times I like to put the rear end up on jack stands, run unit for ten to fifteen minutes, working the sticks, let sit for an hour then repeat.

 

[jasonbutler]

Those units can be a real bear to purge. I’ve had to repurge a few 3-4 times before I got all the air out. Most times I like to put the rear end up on jack stands, run unit for ten to fifteen minutes, working the sticks, let sit for an hour then repeat.

i for sure appreciate any info on this thing as i and a Wright guy lol. ive read it can be a lengthy process to purge them..... i just today went ahead and pulled pump and motor back off replaced all o rings and ordered a new motor seal kit.... im hoping it was just something minor fluke perhaps....