My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

any ideas what valve is in a l3400 DT-f 75xxx

So, far I don't know the serial # break for the latest valve to be published. If the hitch works in limited broken movements but doesn't jerk the machine to much and was purchased or built before 2008 it's probably P/N: 31351-39604.

If it seems worse than above and you bought in 2008 or later then maybe P/N: YR908-00102. We know very little about this valve other than it's generated some complaints and it replaced 31351-39604. Messicks noted it to be an anti-fall valve?

Messick's posted the serial number breaks on 1-16-2006 for the original upgrade to valve 31351-39604, maybe he can help us find out when Kubota switched to YR908-00102?

Boy, if Neil answered everyones requests he wouldn't have time to run his business. I appreciate every one of his comments, even when I disagree. Now if he could just slip us the password to that "online service center" Kubota keeps.

 

[ht1]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

My hitch seems to operate closer to the bad part # but not quiet as bad,
my tractor was bought new in May of 08'. One thing I noticed from some
of the diagrams is that my position control rod that links the 3 point hitch
to the position control valve is straight, and the rod in the diagrams has a bend in it. Also my position control rod rubs on the top of my differencial.

 

[MessickFarmEqu]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Messick's posted the serial number breaks on 1-16-2006 for the original upgrade to valve 31351-39604, maybe he can help us find out when Kubota switched to YR908-00102?

It was a very recent change. From what our documentation says it was a switch to an anti-fall valve. It was nothing related to what you guys have been talking about.

 

[ccsial]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

It was a very recent change. From what our documentation says it was a switch to an anti-fall valve. It was nothing related to what you guys have been talking about.

Could it be one of those "fixed one thing, broke another" ?

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

It was a very recent change. From what our documentation says it was a switch to an anti-fall valve.

Seems so self explanatory but can anyone describe exactly what an anti-fall valve is? And maybe why they might switch to one, at this point?

 

[EE_Bota]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

If most of you are now satisfied with your lift, and now consider this an intellectual pursuit, knock yourself out, and enjoy! I am covered up with too many such pursuits, and I was mainly interested in having people like their lift performance, not so much the hydraulics....too much like work. The link below may get you started.

If you read at least 5 pages of this link, you will begin to see what you are up against, and why guessing what goes on in certain valves that look similar, but perform differently, is not likely to be that much fun. (Heck...depends what you consider fun I guess.)

(remember..yours are open center proportional, since a solenoid valve would be discreet (bang-bang)...a bit of a trick.)
Oil Hydraulic Systems: Principles ... - Google Book Search

I hope the link does not go stale quickly..it is a book preview. It discusses land overlap of spool valves, reaction forces, over reaction, etc in probably as much fun detail as many of you would like! It's fairly easy reading if you are used to reading such things.

As for the question of what is a anti-fall valve. It is to keep the lift from falling. But..beyond that...it could be accomplished in a number of ways, and for a number of reasons, all of which apply. If the lift control lever was in the up position and the lift were moving up..at the same time a power beyond hose bursts, the lift can fall. If the spool were cut to accommodate smoother lifting, some cuttings would require a check because for brief periods, the cylinder, tank, and pressure port can all be connected together. You would not like asking the lift to go up, only to have it drop a bit first, then go up.

As for what is the device itself....if can be a check valve (least likely), a pilot operated check valve (perfectly acceptable), or if the lift quarter-inches up AND down, it is most likely a rate based device that does nothing unless the oil exits the cylinder faster than a pre-set speed, and that will cause the valve which has NEVER moved before to suddenly shift and lock down the hydraulics so that the lift will never go down again until such time as it is raised first. Scissor type material lifts often have this, and sometimes call it a hose burst safety valve. Good luck!

 

[ccsial]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

It's interesting that Jap hydraulic engineers in 1982 could make a silky smooth 3PH on a fairly simple CUT, witness my Ford 1910 by Shibura, and today Kubota can no longer do that.

 

[canoetrpr]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

ccsial:

Having never owned a tractor before, how silky smooth is your old Ford's?

Does it have an infinite range of increments and how sensitive is it to the position control?

I'd be really interested to compare to the 1/4 inching variety that we have with something that is really smooth - both with weight on it.

 

[GMtb42]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Update ;
I got the spring and washer today , and put it in the LCV , it does make a small amount of difference in the lift speed , slower , and responsiveness to movement , slower .
There has to be something inside the smooth PCVs that we can't see that is different , different sized ports , more , less .
Another piece to add to the puzzle .

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Thanks EE_Bota, again for all the help! Great link too, I hope to spend some time reading up.

Wow GMtb42! Glad you gave it a shot! It's great to have your piece of the puzzle.

Would you say that it is better with the spring or just different? If it's better, was it worth the approx. $10?

I know the smooth PCV has an extra spring.

 

[GMtb42]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Would you say that it is better with the spring or just different? If it's better, was it worth the approx. $10?

I know the smooth PCV has an extra spring.

Personally can't draw to much of a opinion as have not actually used 3P yet , in a couple of weeks I have to grade a road with BB and will give report then .
If anyone else has a 1/4" PCV try it and let us know !


Gil

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Regraded my driveway today with my BB.

Smooth as a babies but, can't say the same for the hitch but it's sooo much better than what I had been working with. I can't believe it, if I knew it could be this good it would have been the first thing I did with my new tractor.

And my new suspension seat rocks! I think this why the lousy PCV, who needs a Grand L when the L3400 is so awesome? What more could you really want from a 34 hp tractor?

 

[Wayne_Freeman]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Now that you have reached the point of being somewhat satisfied with your 3 point can you tell me what is the primary part we should replace on our 3400's? I for one would like to give it a try. Thanks for all you work on this.

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

The part that makes the difference is the PCV, P/N: 31351-39604. Not the easy fix though. And it won't work for everyone because a lot of L3400's came out of the factory with it. (see post 150 if your not sure)

It's important to note, it doesn't solve the "jerking", just makes it seem acceptable.

The LSV modification/change appears to have some relevance but it only makes the bad valve worse.

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

I vaguely recall someone posting here who had changed to an over-the-self UDT compatible hydro fluid and he claimed that his hitch was quite smooth after that. I can't find that post though. I'm wondering if a fluid that does not flow as easily as the SUDT or Premium UDT stuff we have in our tractors is helping even things out a bit.

FOUND IT!!

http://www.tractorbynet.com/forums/kubota-owning-operating/110380-bad-news-kubota.html#post1260255

And guess what, the OP is still an active member. I'm going to PM this man and see if he'll fill us in, maybe get a video of his hitch in action.. and we need his S.No. to gather what valve he had to begin with. (minus the last digit or two)

 

[teg]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Just thinking out loud... (something about being a fool and removing all doubt)

He had taken apart his rear axle housing after hitting a tree and I wonder if something was done differently when he reassembled? It didn't sound like he messed with the area of the 3ph but he did drain SUTD and filled with UTD.

Does every L3400/L2800 (with the serial numbers of "bad" valves) jerk or are some more jerky than others? If there are some that are not jerky, What fluid was used. Or, when you refill the UTD, is the 3ph up or down - does that make a difference? If the 3ph is up, does that mean the piston is full of UTD or emtpy???

Since those of us that got the new valve... the problem disappeared... I would guess what I wrote above is the rambling of a mad man... and that I'll most likely regret posting this in the morning but what the heck...

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Just thinking out loud... (something about being a fool and removing all doubt)

Hey, I know how that feels. I was thinking the same thing after my last post. But I sure would like to know more about ctpres's repairs and results and see a video if possible. If his hitch is really smooth, I want to know why. If it were only the fluid, I'm surprised it wouldn't be all over this board by now. Maybe he figured out another piece of the puzzle, maybe it has something to do with that repair he did?

When the 3 pt is up, the cylinder is full of fluid and the piston is extended.

 

[slowzuki]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Sure they can, on the tractor models that have that feature. I doubt the cost cutting measure on the econo models is really worth it for all the bad press it generates.

It's interesting that Jap hydraulic engineers in 1982 could make a silky smooth 3PH on a fairly simple CUT, witness my Ford 1910 by Shibura, and today Kubota can no longer do that.

 

[GMtb42]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

FOUND IT!!

http://www.tractorbynet.com/forums/kubota-owning-operating/110380-bad-news-kubota.html#post1260255

And guess what, the OP is still an active member. I'm going to PM this man and see if he'll fill us in, maybe get a video of his hitch in action.. and we need his S.No. to gather what valve he had to begin with. (minus the last digit or two)

That is the exact same fluid I have in mine , with the new PCV and the modified LCV (spring/washer) and it is still not buttery smooth , I don't think we will ever get the 1/4" movement out of them unless a new valve is installed that has no inching settings in it .

 

[ccsial]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

ccsial:

Having never owned a tractor before, how silky smooth is your old Ford's?

Does it have an infinite range of increments and how sensitive is it to the position control?

I'd be really interested to compare to the 1/4 inching variety that we have with something that is really smooth - both with weight on it.

Sorry I've not been here for a bit. The best way to describe my Ford is "infinite smooth". There really are no increments. You can move the lever as slow as possible and it follows just as slow, up or down.

I guess you could think of it as analog while the L3400 seems low resolution digital.