2007 John Deere Z425 zero turn - right side wheel not turning

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bryanfaz

Member
I was working on my 2007 John Deere Z425 this week and really screwed up. I had the machine in free roll and went to tighten the bypass valve rods and turned the one on the right the wrong way. I didn't recognize the mistake until the rod was about to come off in my hand. I reversed course and tightened the rod but that side no longer works properly. I'm trying to bleed any air from the hydraulics...jacking the mower up, loosening the bypass valves, starting the mower, press control lever forward then backward several times. When I push or pull the control lever(s) the wheels do turn but very weak. The right side does not pull enough to move the machine forward or reverse. This is the first time Ive ever had any issues with the drive mechanism. Any ideas on what this might be and how to correct it?

Thanks
Bryan
 
Let's see if we can on the right setup first. What is the mower's serial number.

What you are posting is contradictory, First you says bypass rods and then you say you loosen the bypass valves.

But I don't think the bypass rods are even adjustable. Now the control arm rods are adjustable. Even that will require knowing which transaxle you have. First level was hydro pump and wheels motors, Second level was a hydrostatic transaxle. And third level was yet again a different hydrostatic transaxle. First level have bypass valves and the two later levels had bypass rods. All three had adjustable control rods.

And pictures what you adjusted and where helps.
 
bryanfaz said:
I was working on my 2007 John Deere Z425 this week and really screwed up. I had the machine in free roll and went to tighten the bypass valve rods and turned the one on the right the wrong way. I didn't recognize the mistake until the rod was about to come off in my hand. I reversed course and tightened the rod but that side no longer works properly. I'm trying to bleed any air from the hydraulics...jacking the mower up, loosening the bypass valves, starting the mower, press control lever forward then backward several times. When I push or pull the control lever(s) the wheels do turn but very weak. The right side does not pull enough to move the machine forward or reverse. This is the first time Ive ever had any issues with the drive mechanism. Any ideas on what this might be and how to correct it?

Thanks
Bryan
Click to expand...
I looked up a John Deere Z425 and it has a Kansaki DUP-10 hydrostatic transmission. Which sounds like it has bypass rods and not bypass valves. Bypass rods=hydro transaxle and bypass valve=separate hydro pump and pump motor with hydro lines. So the question is, which is it?
 
You better look again as the Kansali DUP-10 is not hydrostatic transmission but is just a dual pump that drive the wheel motors.

Early Z425 used this system. Mid models use a HG ZT2800 and late use a TT TZT7D hydrostatic transaxles. This which why we need the serial number.

The DUP-10 had bypass valves while the HG and TT had bypass rods.

So please pay close attention to the IPLs.
 
StarTech said:
Let's see if we can on the right setup first. What is the mower's serial number.

What you are posting is contradictory, First you says bypass rods and then you say you loosen the bypass valves.

But I don't think the bypass rods are even adjustable. Now the control arm rods are adjustable. Even that will require knowing which transaxle you have. First level was hydro pump and wheels motors, Second level was a hydrostatic transaxle. And third level was yet again a different hydrostatic transaxle. First level have bypass valves and the two later levels had bypass rods. All three had adjustable control rods.

And pictures what you adjusted and where helps.
Click to expand...
My ignorance of the correct terms is apparent. I hope these pics help. JD2 is the ID of the mower. The middle pic is THE object I turned. If sitting on the mower, it's on the right side of the Tuff Torq hydraulic "pump"? I've jacked the mower up and the control arm on the right is able to move the tires. But when i lower the mower to the ground, not enough power to turn the wheels on the right side. Left side works great.

I had loosened them to move the mower while I was changing the deck belt. Never had any issues with the propulsion of the mower. I didn't realize which way the rod was actually oriented and just turned it too many times, the wrong way.

Thanks!
Bryan
 

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StarTech said:
Let's see if we can on the right setup first. What is the mower's serial number.

What you are posting is contradictory, First you says bypass rods and then you say you loosen the bypass valves.

But I don't think the bypass rods are even adjustable. Now the control arm rods are adjustable. Even that will require knowing which transaxle you have. First level was hydro pump and wheels motors, Second level was a hydrostatic transaxle. And third level was yet again a different hydrostatic transaxle. First level have bypass valves and the two later levels had bypass rods. All three had adjustable control rods.

And pictures what you adjusted and where helps.
Click to expand...
Did the pictures help??
 
Yes pictures help verify which of the three units you have. Basically you have a dual pump and two wheel motors.

The item with the T bar is not an adjustment, it is just a bypass valve that is either open or fully closed. Closure is done RH until until seated. You open it to move the mower when the engine not running.

The only adjustment that can be done is the neutral position. This done at each lap bar assembly. Basically it is done to keep the mower moving in neutral IE lap bars outboard.

Sorry for the late response, had to recover from yesterday's heat and I got at least three more days of heat index of 110+. Then it rains and turns into a stream room. Just too blame hot in the sun on asphalt to work.
 
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Tiger Small Engine said:
Has a bypass rod on the transaxle. It is either in or out, engaged or not engaged. Try working it back and forth and going through the purging process for air in the system.
Click to expand...
Thank you for getting back to me. When you say work it back-and-forth, do you mean the control arm? Heavenly the control of the armies are that I use to steer and propel the mower, right? I have had it out in the yard trying to work it out, pushing it forward backwards. Something just isn’t catching, mocking, or engaging. It just does not happen enough power to equalize thrust from the left side if I’m on a flat surface are going downhill, it can provide a little proportion, that being the right side. Otherwise, that right side is just dead. I can’t imagine what happened with that T Rod was loosened too much.
 
Now there is an o-ring on that bypass valve that could have got damage. The problem is not available separately from a seal kit or a bypass valve kit which BS in my opinion. Nothing else they could have at least gave us the o-ring size.

Seal kit PNs

JD MIA880511
Tuff Torq 17808010601

Over 98 USD

BYpass valve kit JD MIA881197 Around 40 USD.
 
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