M5700 shuttle shift issues

[bronccat]

Hi all, first post.

2003 M5700 4WD Hydro Shuttle shift
Near 400 hours

Was bush hogging and all of a sudden when I threw from F to R she bucked like crazy. Changed filters, cleaned magnet, fluid looked good.

Pretty much at any rpm if I shuttle from F to R or R to F it shifts very hard. If I clutch or stop first then shift no issues. Not lunging much of at all from a dead stop.

I'll just say it's fairly violent when I shift on the fly. Any input is appreciated.

TIA

 

[bronccat]

Anyone? Thanks

 

[Tx Jim]

Welcome to GTT
I presume you're referring to hyd shuttle. If so I will guess modulation valve has failed allowing full hyd pressure when shifting reverser. Do you have a WSM?

 

[North Idaho Wolfman]

I would say most likely cause is an issue with the shuttle valve.
If it's under warranty take it in as that system gets really complicated really fast.
If it's not under warranty or if you just want to go it yourself (I'm that way), get the WSM P/N 9Y011-18106, it will give you a troubleshooting guide and procedures to test and repair the system.

 

[Bulldog]

I see you said the filters were changed. Did you change the fluid and if so what did you use?

Didn't know if the problem started before or after the service work was done.

 

[bronccat]

Thanks All

Yes, Hydraulic Shuttle Shift. I assume way out of warranty as it's a 2003 model

 

[bronccat]

Changed filters but did not change fluid. 400 hours on fluid, looked clean.

Not much metal in magnet.

Used the Kubota fluid to top off

Started before filter change

Don't have WSM

Normally DIY but in the middle of kitchen remodel, daughter wrecked car, building a bronco, blah blah blah - fixing to go Amish LOL

 

[rbargeron]

.........Was bush hogging and all of a sudden when I threw from F to R she bucked like crazy....... at any rpm if I shuttle from F to R or R to F it shifts very hard. If I clutch or stop first then shift no issues.......

I've had several different Kubota hydraulic shuttles - the earlier ones were all very fast to shift if the lever was moved from F to R in one motion. I got into the habit of using two motions - F to N, then N to R with maybe a half-second wait between. This short delay allows clutch pressure to drop before being applied to the other side.

Over the years, the valving has been redesigned to help accomplish this internally - but high-rpm shifts can still be abrupt - especially when the oil is hot. Even with newer ones like yours, moving the lever in two distinct motions is easier on everything - including the operator.

There could be some skudge caught in an orifice somewhere. Modifying the shuttle technique is easier than taking the valve apart looking for a cause that might not even show itself. Hope this is useful - Dick B

 

[bronccat]

I've had several different Kubota hydraulic shuttles - the earlier ones were all very fast to shift if the lever was moved from F to R in one motion. I got into the habit of using two motions - F to N, then N to R with maybe a half-second wait between. This short delay allows clutch pressure to drop before being applied to the other side.

Over the years, the valving has been redesigned to help accomplish this internally - but high-rpm shifts can still be abrupt - especially when the oil is hot. Even with newer ones like yours, moving the lever in two distinct motions is easier on everything - including the operator.

There could be some skudge caught in an orifice somewhere. Modifying the shuttle technique is easier than taking the valve apart looking for a cause that might not even show itself. Hope this is useful - Dick B

Thanks. Don't think that's the issue. It's been doing great for 10 years - fast, smooth, seamless shift regardless of RPMs.

I now wonder if maybe the fluid isn't as good as I thought but mixing in 2.5 gallons of new SUDT should have brought me back to good (functional) viscosity (I would think)

Probably the shuttle valve though :-(

 

[rbargeron]

You say you "don't think that's the issue" and then you go on to say its probably related to viscosity, probably the shuttle valve. That's exactly what I was saying. The shuttle valve system has orifices that control the shift rate.

 

[bronccat]

You say you "don't think that's the issue" and then you go on to say its probably related to viscosity, probably the shuttle valve. That's exactly what I was saying. The shuttle valve system has orifices that control the shift rate.

I was speaking to part of your response, not in it's entirety - I suppose I should have clarified. Yes, I did agree with your last statement but I certainly don't think high RPMs or oil temp are the root culprit as this is a entirely new issue that appeared instantly after shifting flawlessly for 10 years.

As to your point about stepping the shift, it doesn't help enough to matter (in my case I have tried) so I have been using the clutch pedal begrudgingly.

 

[rbargeron]

Oh, sorry, I didn't know you'd already tried stepping the shift. There is a general WSM PDF here on major components. A discussion on the 3A051-23803 shuttle valve starts on page 21.

The shuttle valve assembly contains several valves. (no dry clutch disk on hyd shuttle model) The clutch pedal connects to the main variable reducing valve. When the pedal is pressed down, pressure to both clutch packs drops to zero. Other shift management functions are bypassed. The issue could be in the accumulator, one of the modulating valves, the shuttle spool, or elsewhere.

Luckily the clutch pedal valve still works so the tractor is usable as-is until you get more opinions. I'd recommend using it as-is and see if the symptoms change or even go away.

Question: If the clutch pedal is slowly lifted with the lever in F or R is engagement gradual as expected? or is there still an abrupt change ?

 

[bronccat]

Oh, sorry, I didn't know you'd already tried stepping the shift. There is a general WSM PDF here on major components. A discussion on the 3A051-23803 shuttle valve starts on page 21.

The shuttle valve assembly contains several valves. (no dry clutch disk on hyd shuttle model) The clutch pedal connects to the main variable reducing valve. When the pedal is pressed down, pressure to both clutch packs drops to zero. Other shift management functions are bypassed. The issue could be in the accumulator, one of the modulating valves, the shuttle spool, or elsewhere.

Luckily the clutch pedal valve still works so the tractor is usable as-is until you get more opinions. I'd recommend using it as-is and see if the symptoms change or even go away.

Question: If the clutch pedal is slowly lifted with the lever in F or R is engagement gradual as expected? or is there still an abrupt change ?

No worries, thank you.

That's my plan, I figure over time something might become a little more obvious.

I will check that. It is definitely better than shuttling, but not sure it is as smooth as it used to me.

Thanks again

 

[rbargeron]

Testing clutch pedal behavior may help confirm whether the issue is in the shuttle valve or perhaps somewhere else. If it still grabs it might point to a problem in the clutch pack (likely would be different for Forward and Reverse). When testing, see if there's a difference letting the pedal up slowly, or at normal quickness like before this came up.

 

[Tx Jim]

DITTO: photo below from M7040 WSM describing hyd clutch valve operation

 

[Tx Jim]

Photo below describing hyd shuttle valve operation.