3-Point Hitch L-series Jerky 3PH - Jeff's homebrew repair.

[merlynr]

From my earlier post I found out that I too have somewhat jerky 3ph when moving it in small increments. So after 2 years of not noticing it I guess that it is what it is and I'm not going to worry about it.

 

[Chilly807]

From my earlier post I found out that I too have somewhat jerky 3ph when moving it in small increments. So after 2 years of not noticing it I guess that it is what it is and I'm not going to worry about it.

Most of us have done just that, too. To me, there's enough good things about the tractor to outweigh the negative of the jumpy hitch.
It's the kind of thing that's a deal killer if you discover it does that before you buy, or even shortly after in some cases.

 

[bigballer]

I don't even really notice this on my 3400 (now with 380 hours). maybe I am just used to it and have adapted my technique to overcome the jerk or mine is not affected as much as others are. What is more annoying to me is the a sticky PTO and HST pedal

 

[k0ua]

I don't even really notice this on my 3400 (now with 380 hours). maybe I am just used to it and have adapted my technique to overcome the jerk or mine is not affected as much as others are. What is more annoying to me is the a sticky PTO and HST pedal

My L3400hst was jerky as all get out, but the HST pedal and the PTO actuator lever both worked very well.

 

[s219]

For all the complaining I have done about the hitch, it's been a non-issue while grading my barn site recently. I have been using the heck out of my box blade, lots of up/down and adjustments, and have not had any issues. I couldn't even get enough jitters out of the hitch to shake off some sticky dirt! I'd almost think the problem went away (will have to try lifting one of my trailers, which is where it was obvious).

 

[k0ua]

For all the complaining I have done about the hitch, it's been a non-issue while grading my barn site recently. I have been using the heck out of my box blade, lots of up/down and adjustments, and have not had any issues. I couldn't even get enough jitters out of the hitch to shake off some sticky dirt! I'd almost think the problem went away (will have to try lifting one of my trailers, which is where it was obvious).

We often hear that some are much better than others.

 

[hugho]

Thank you Jeff for an amazingly well done and thought out fix. I am buying a used 3400 and your post was very useful.

*** I will return to this thread and fill in this post with a great more details as I get the chance.***

For now, you can watch this Youtube video and read the extended description.

Kubota L3400 - 3PH Action @ 2000 RPM - YouTube

Quick summary:

L3400 with extremely jerky 3PH (violent) with old YR909-00100 PCV. We bought the tractor used this winter, and were quickly and thoroughly disgusted by this fundamental problem. I dismantled and studied the PCV system and made the mods early this spring. Have been using the tractor like this all summer and am very happy with the result.

1. Disassembled the PCV and chamfered the spool control edges by ~200 um. This increased PCV response and reduced the violent jumps from 1" down to less than 1/4".

2. Added an external pressure compensated flow control valve ($~90 + lines and fittings). This reduced the flow to the 3PH system and took the violence out of the 3PH motion. It also reduced the lift speed though this is now adjustable. It did not affect the 3PH lift capacity or the FEL in any way.

I will fill in the blanks, and explain much more thoroughly later as well as show photo's and a part list of the install.

Cheers,
Jeff

 

[hugho]

jeff could you elaborate on your chamfer of the spool control valve. You removed 200 microns(?) from where exactly?

 

[Atlanta Panther]

Did Kubota ever fix this problem for the L3200? I have 200 hours on mine...long past warranty and had just put up with it. Being new to tractors when I bought it, I didn't know any better. I can certainly live with it and have since I bought it 5 years ago but it would be nice to have it fixed once and for all. I don't have the skills/tools necessary to do the mods suggested in this very good solution that the original poster put forward.

Any luck with Kubota?

 

[Chilly807]

Nothing in my case. Kubota corporate wouldn't admit there was a problem to begin with, so the dealership, although sympathetic, weren't willing to try to repair it without support from Kubota.
The only success I had was adjusting the position control valve to factory specs. It eliminated the jerky performance but introduced other issues that were worse.
A flawed design that the company refused to acknowledge.