Replacing another Wheel Motor.

   / Replacing another Wheel Motor. #1  


Veteran Member
Jul 5, 2005
Harpers Ferry WV - Mountains of Shannondale
Former owner of a P T -180 / Kubota BX-1500 .. A Craftsman Yard Tractor / John Deere 140 H-1 / Cub Cadet 108. And now ( Little Red ) a Power Trac 1425
Well was time to replace another Wheel motor on the old girl =1425. The old one was leaking hydraulic fluid just a matter of time before I had a seal blow out. Probably in the middle of a snow storm with my luck. Anyway Getting the hubs off was a lot fun as usual. You can see with my first wheel puller the shaft bent and it still didn't budge the frozen wheel hub even after applying heat...

This time I decided to pull out the Big Boy. A 12 ton hydraulic puller.. It bent the old hub in three places before it shot off across the floor like a Rocket... The new one is much thicker .. I always stand to the side and wear shop goggles when doing anything like this. I know if it would have hit my leg it might break a bone or at least put a big indent in the shin ...

Now to replace the wheel motor and get messy with hydraulic fluid everywhere .. Had some coffee now back to the shop .. New motor installed .. Next take off my all metal gas tank replace the petcock put on new lines and clean out any debris that may have accumulated over the years still loving this old machine the Kohler runs like a top..


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   / Replacing another Wheel Motor. #2  
Nice going. Did you use PB Blaster or the like on the hub? I have had it work wonders.
   / Replacing another Wheel Motor.
  • Thread Starter
Thanks Bob yes I did.. As you know every little bit helps .. 👍
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   / Replacing another Wheel Motor.
  • Thread Starter
Turning the wheel while up on blocks.. I noticed a slight grinding on the opposite side rear wheel motor, which I plan to replace next ., Anyone know if one of these wheel motors can have a good seal but a bad bearing ?
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   / Replacing another Wheel Motor. #5  
Sadly, yes.

The bad news about a bad bearing in the drive system is that the particles get circulated around the wheel motor hydraulic circuit without filtration.

All the best,

   / Replacing another Wheel Motor. #6  
I think that about 4 gallons a minute is makeup oil which is filtered.
   / Replacing another Wheel Motor. #7  
Dear Bob,

That's an interesting number; can I ask where you got it from?

My understanding was that the charge pump kept the low pressure side of the system charged, and that most of the charge pump flow was dumped back to the reservoir, rather than through the pump circuit. I had read that a typical specification for the charge pump was on the order of 10% of total flow, but that most of that was passed through the pump, rather than bleed from the drive circuit. c.f. Danfoss pump design document, where they have some interesting plots on how much the temperature drops with a fluid bypass line from the pump that would divert up to 10% of the total flow. The specification in the document is that the variable volume pump would bleed about 5ml/min from the charge pump. (Yes, ml, i.e. about 4 grams).

Just curious. I still don't know what all of the hoses do on my tractor.

All the best,


I think that about 4 gallons a minute is makeup oil which is filtered.
   / Replacing another Wheel Motor.
  • Thread Starter
Bob / Pony .. Can either of you elaborate. Is the oil that is circulated in the drive system filtered to some degree. Or do I need to find a way to flush out the contaminated oil after I change out the other wheel motor with the bad bearing . Thanks for your input.. Appreciate it 👍
   / Replacing another Wheel Motor. #9  
I will try to find it. Later
   / Replacing another Wheel Motor. #10  
The way I understand it is any hydraulic oil that enters the tram circuit is filtered as it leaves the tank, then goes to the charge pump in the tram pump. Anything that leave the tram circuit returns to the tank. So if you're driving along forward, the tram pump is pushing fluid forward, through all of your wheel motors and back to the tram pump. The 400 series wheel motors don't have case drains (that I know of), so all fluid goes through all wheel motors and back around through the tram pump. Anything that leaks past the seals inside the tram pump is where it goes back to the tank from the tram circuit.

So, if a wheel motor tosses chunks of metal internally, they're gonna circulate around inside the motor, back and forth in the wheel circuit(s), and perhaps make their way to the next motor or the pump. To get filtered out, they'd have to pass through the tram pump, into the tank and manage to get picked up in the sucktion for the filter to get back into the tram pump.

As far as I know, the main and aux PTO pump circuits are never filtered.