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

   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #1  

Harvest Moon

Gold Member
Joined
Nov 16, 2007
Messages
357
Tractor
Kubota L3400 HST-F
My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

For those who have been following the research stage of my quest, thanks for your help, input and support... you'll probably want to skip to the paragraph starting with "So." For those new to this quest, here is a little background:

The L3400 (and the L2800) has had four different position control valves (PCVs) installed in it during different stages of production.The first was infamously dubbed the "inching valve" because of it's tendency to jerk in one inch increments. The second, which is installed in my tractor, may be slightly better, allowing a random adjustment range from one quarter to one inch increments. The third is a valve seen in several Grand L tractors and allows relatively smooth quarter inch control. The fourth has contributed to recent reports of performance similar to the first two valves... definitely a step backwards.

Reports show that the Grand L tractors, using the only PCV known to produce acceptable results in the L3400, have nice smooth performance. But when this valve is installed in the L3400 the results are still somewhat jerky.

I believe the lowering speed valve (LSV) is the missing link between the Grand L's smooth performance and the L3400 somewhat jerky performance when using the same PCV. The L3400's LSV is virtually identical to the Grand L's with the exception of a spring. It also appears that the key difference between the Grand L PCV and the jerky L3400 PCVs is two springs.

I'm betting that the three small springs, one in the LSV and two in the Grand L PCV provide the fluid regulation or pressure dampening responsible for smooth hitch operation in the Grand L machines and the lack of them is the reason for the L3400's jerky performance. I believe those with the Grand L PCV installed in their L3400's are roughly 2/3's the way home and that addition of the Grand L LSV would produce Grand L results in their L3400's. The LSV appears to be an adjustable check valve that has the potential to dampen the inflow of fluid and slow or stop the out flow. Although not confirmed it appears that the LSV from the Grand L's is interchangeable with the L3400.

So, this week I will begin the process of putting my theory to the test. Within the next few days I am going to order the lowering speed valve (LSV) from the Grand L's and take a video of my hitch performance as it its and then attempt to post it. Shortly after I receive this new valve I will know if it is interchangeable... if it fits I will take another video to show the results and a few photos to show the installation. I am expecting about a 20% to 30% improvement, which may be somewhat subjective.

At that point, either way I'll probably replace, and document if I do it myself, my position control valve (PCV). That will be a more expensive and complicated job.

I can't help but think that there are a few of you out there that think I'm a bit nuts already and I can't help but fear a few of you know this won't work.... If you're one or the other, please feel free to speak up, you won't ruin my day. I'll try to document my quest each step of the way. Be patient, I'm not in a hurry. Should I fail, I'll let everyone know and then consider changing my user name and keeping a bit lower profile! :)

Have a great day! I'm on my way!
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #2  

JOHNTHOMAS

Super Member
Joined
Apr 14, 2008
Messages
7,720
Location
Somerset, Ky
Tractor
F2690 4WD RTV X1140 MX5400 HST ZD1211
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

I have no idea if your plan will work but good luck on your venture. I had a B7800 with the quarter inching valve but now have a L3240HST so I understand your desire for improvement.
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #3  

canoetrpr

Veteran Member
Joined
Aug 7, 2005
Messages
2,382
Location
Ontario, Canada
Tractor
Kubota M7040 cab/hyd shuttle - current, Kubota L3400 - traded
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Harvest - you are DA MAN for taking on this effort. The rest of us will be watching keenly.
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #4  

jeff79m

New member
Joined
Oct 17, 2008
Messages
4
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

As a new L2800 owner with this same issue I am very interested in your findings.

You said that springs are different can they just be swapped out without replacing the whole valve? Or is the diameter of the spring different?

Also were exactly is the valve located?
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400
  • Thread Starter
#5  
OP
H

Harvest Moon

Gold Member
Joined
Nov 16, 2007
Messages
357
Tractor
Kubota L3400 HST-F
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

jeff79m, my best advice is to head over to Kubotabooks.com and download the L2800 and the L2900 parts book and take a look. The L2900 doesn't have the latest PCV but it's very similar. You'll get better answers from the source.
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #6  

ShivasIrons

New member
Joined
Feb 10, 2008
Messages
18
Location
Atlanta, Ga and Perry Co. TN
Tractor
Kubota L4240
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Good luck Harvest. I will be anxiously waiting for your updates.
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #7  

Adiredneck

Gold Member
Joined
Sep 14, 2006
Messages
490
Location
Upstate NY
Tractor
2006 Kubota L3400DT, Kubota L5240
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Good work!
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #8  

jeconn

Bronze Member
Joined
Oct 3, 2008
Messages
56
Location
Hudson, NC
Tractor
Kubota L3240
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

You know I'm watching!
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400 #9  

jeff79m

New member
Joined
Oct 17, 2008
Messages
4
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Thanks for the Kubotabooks.com site!
 
   / My quest for "Grand" 3 point performance from my "economy" tractor. The L3400
  • Thread Starter
#10  
OP
H

Harvest Moon

Gold Member
Joined
Nov 16, 2007
Messages
357
Tractor
Kubota L3400 HST-F
Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Slow but steady, made my "before" video and ordered the valve. Wasn't in stock but I should have it next week sometime. $90.71.

Now, if I could just get everyone who will want to see if this works to mail me one dollar... (just kidding, not soliciting) :D

I'll try to get the video up tonight or tomorrow.
 
 
Top