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!
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!
