Kubota M6800 shuttle shift needs repair

[shorn]

I am searching for a repair manual for my M6800. My shuttle shift binds shifting forward. I've lubricated all the linkage which seemed to help but it is binding once again. I have not had any luck locating a repair manual for the M6800. I purchased a service manual put it is only an assembly manual and gave no indication as to what might be the problem nor how to repair such a problem. ANY help would be greatly appreciated.

[Service Dept Vic]

I should be able to get you that via Kubota Canada. They're usually around $95-125, and the only manuals we use here in the shop. Send me a PM if you want me to check with the Publications Dept on Monday.

If you've lubed all the linkages and have not found anything binding then the problem may be an incorrect shuttle valve pressure setting.

Kubota released a tech bulletin detailing correct pressure settings required on the M5700 and M6800.

If the pressure setting is out of range the operator may experience difficulty shifting when the engine is operating off idle, and while it may not be the problem with your tractor, it's worth taking a look at to rule it out.

The correct Shuttle Valve System Pressures for the M6800 are as follows:

Measured at the "M" port or Modulation Valve Port, this is basically operational Oil Pressure, pressure should be between between 355 and 370PSI, with the engine at 2800rpm, the shuttle lever in "Forward", and the clutch fully pressed. "F" port pressure, or Forward pressure, and "R" port pressure, Reverse pressure, must be zero with the clutch pedal depressed, same engine rpm.

With the clutch pedal released, and the shuttle kept in the "Forward" position, "F" port pressure should be between 232 and 276 PSI, "R" Port pressure needs to stay at zero.

Shifting the shuttle to "Reverse", and fully depressing the clutch, F and R ports should register "0" PSI, M Port should maintain 355-370 PSI.

Still keeping the shuttle lever in "Reverse" with the clutch pedal released, "F" port should register "0" PSI, "R" Port will now show 232-276 PSI, while pressure checked at the "M" port, maintains 355-370 PSI

Finally, put the shuttle lever in the "Neutral" position, "F and R" ports will show "0" PSI, and "M" port pressure should indicate 38-41 PSI.

If conducting this pressure test on your own, be advised the pump pressure can exceed 700 PSI, and you need a special guage for this testing.

It's something that could explain the binding, or "lock-out" that you are experiencing when trying to shift. It may be residual pump pressure or bypassing rather than external linkages that are binding.

[Mr. K]

Hey shorn,

Any update on this? Did Vic's advice work for you?

[shorn]

Hi, I am still working to make contact with VIC to arrange to purchase a repair manual. I haven't tried testing the pressures yet I have to obtain tool(s) to do so.

[Service Dept Vic]

Shorn, Kubota published only one WSM manual for your M Series KubotaTractor and as you have found, they are ofen a little short on some procedural details.

I think this is because the manuals are published for the benefit of Kubota's franchisees, for use by their service dept techs who have apprenticed and are accomplished diagnosticians.

If you're going to fix that tractor, read all you can, ask us questions, talk to other owners. It's all I can offer you at this point.