M5700HD Shuttle Issues

[JPCoyne]

Good day. Seems like we have more issues then originally thought on our tractor. M5700HD with a lil over 2000 hours on it. Once this unit was getting warmed up, we were losing the ability to move forward. Also, even when cold, you could push the brakes and lets call it disengage the forward clutch pack ( would kick the hyd pressure out and you would have to move the shift lever from F to N then back to F). We checked all the basics, fuild level, linkage all with spec for the shuttle valve, filters changed and system primed. Preformed the shuttle valve system pressure test and found that we weren't getting proper pressure on the forward port. Disassembled the valve and found a broken spring and worn components. Contacted Kubota whom stated because of the year of this tractor they dont offer any components and we had to purchase a new valve. Pulled the trigger and install the new shuttle valve. Now we have proper pressure that matches the range in the WSM. Something is still wrong. When cold, takes about 2 seconds once FNR lever in F and clutch pedal is lifed to start to move forward and then the Modulation port pressure gets into proper range, R is a like faster maybe 1.5 Secs but pressure is the same as the F. Once tractor gets warmed up time frame increase by 2 seconds or so ( 4 seconds to start to move forward, Reverse is around 3 seconds). Kicker added to it, if you are turning the wheel while in forward or reverse and lift the pedal to go to drive you will get nothing on the Modulation test port. Let go of the wheel and in about 2 to 3 seconds pressure will build in the test port and you will start to move.

260psi at 2600 rpms with the pedal fully pressed and free in both forward and reverse on the M port. Forward and Reverse test ports are at 265ish psi when fully engaged. But if hot and turn the wheel hard, nothing. I fell as if its a upstream issue, Hyd Pump or possible the oil cooler relief valve. Was wondering yalls thoughts.

https://drive.google.com/file/d/1ZlyX8nqBCrZci9NTZbGvZwmoT-sCrMc_/view?usp=drive_link

 

[PoTreeBoy]

Good day. Seems like we have more issues then originally thought on our tractor. M5700HD with a lil over 2000 hours on it. Once this unit was getting warmed up, we were losing the ability to move forward. Also, even when cold, you could push the brakes and lets call it disengage the forward clutch pack ( would kick the hyd pressure out and you would have to move the shift lever from F to N then back to F). We checked all the basics, fuild level, linkage all with spec for the shuttle valve, filters changed and system primed. Preformed the shuttle valve system pressure test and found that we weren't getting proper pressure on the forward port. Disassembled the valve and found a broken spring and worn components. Contacted Kubota whom stated because of the year of this tractor they dont offer any components and we had to purchase a new valve. Pulled the trigger and install the new shuttle valve. Now we have proper pressure that matches the range in the WSM. Something is still wrong. When cold, takes about 2 seconds once FNR lever in F and clutch pedal is lifed to start to move forward and then the Modulation port pressure gets into proper range, R is a like faster maybe 1.5 Secs but pressure is the same as the F. Once tractor gets warmed up time frame increase by 2 seconds or so ( 4 seconds to start to move forward, Reverse is around 3 seconds). Kicker added to it, if you are turning the wheel while in forward or reverse and lift the pedal to go to drive you will get nothing on the Modulation test port. Let go of the wheel and in about 2 to 3 seconds pressure will build in the test port and you will start to move.

260psi at 2600 rpms with the pedal fully pressed and free in both forward and reverse on the M port. Forward and Reverse test ports are at 265ish psi when fully engaged. But if hot and turn the wheel hard, nothing. I fell as if its a upstream issue, Hyd Pump or possible the oil cooler relief valve. Was wondering yalls thoughts.

https://drive.google.com/file/d/1ZlyX8nqBCrZci9NTZbGvZwmoT-sCrMc_/view?usp=drive_link

First, it sounds like you have a WorkShop Manual, but, if you don't, you can download it at KubotaBooks. The HD model gets its own sections in an addendum near the end.

You say you recently changed both hydraulic filters, correct? Tell us a little about these symptoms - did it start recently or has it behaved this way since you've owned it?

Here's the steering/shuttle diagram

I may have missed it, but I don't recall a troubleshooting guide in the clutch/transmission sections. So, I'd start by checking the modulating pressure at the A test port. With the transmission in N and the clutch engaged, it looks like the pressure should be 600+ psi. Fully disengaged, it should be minimal.

Much less than 600 would indicate a problem upstream, cooler, cooler relief, steering box possibly. Let us know what you measure.

EDIT, I missed that the shuttle shift bleeds off the modulator in neutral, so you won't see 600psi. Here's the test pressures, M port in the chart corresponds to the A port on the hydraulic diagram.