Kubota L3301 Pressure Relief Adjustment?

[Scott65]

Hey guys. I've been a little curious about increasing the pressure on my new L3301, seems like its a little weak, won't pick up the front end without "driving into it". Sometimes struggles to pick up a bucket full of material, etc. I've wondered if its maybe kinda like the expiration date on your milk jug? I know they set a limit, but can you maybe get away with just a little more?

Anyways, I haven't been near curious enough to actually modify anything on a brand new tractor. But I've been reading around, about to add my 3rd function to the FEL for a grapple, and just stumbled across a thread about people doing exactly this on the BX series tractors, fixing the exact same complaints with their tractors, with much success. So thats promising. I've looked around but can't find any threads pertaining to my model though, and the pictures and tutorials in that BX thread are much different. I may just be wording my search wrong. Can someone point me in the direction of an existing thread? Otherwise, maybe we can start one here. What are the pro's and con's, has anyone done this, and how?

Here's what I know so far (at least I think, correct me if I'm wrong)
My model has no factory (or otherwise, yet) backhoe like the BX thread mentions, so I would probably tap into the FEL quick connects
I need to T in a pressure gauge to know where I start and where I end up, no guessing
My factory system uses a pressure relief that is built into the FEL valve body

I know that the L3200 is very much alike to my 3301, but I'm not sure about in regards to this process. So if someone can verify, then going off of 3200 procedures and specs will probably make things much easier

I believe some models use shims, some use an adjusting screw, anybody know which I have?

Or, if someone knows where to get a shop manual (not an owners manual) for such a new model, that may answer all questions. And I will post back up with a tutorial.

One last thing, there was a link to a very neat website, bxpanded.com. Anybody know of an L series equivalent? They offer a gauge setup already complete with adapters to plug into the system, pretty handy.

 

[J_J]

You can build yourself one of these for about $30.

As far as pressure, If you call Mesnick's Kubota, and ask for technical support, they will tell you the relief pressure setting for your tractor.

Kubota Parts | Full Service online retailer

If you do increase it, be careful as those pumps are not cheap.

At least, check it to specs.

3000 PSI 2.5" LF LM GAUGE

 

[Scott65]

JJ, as always, thanks for your help! This tractor is brand new, I bought it only a month or two ago. I've racked up about 60 hours so far, but its been weak like this since day one, so I don't suspect anything has changed since showroom condition. Do you think it was set too low from the factory? The reason I ask, I assumed I wouldn't be looking to adjust my brand new tractor to factory specs. I figured I was about to set out to push it beyond their preset limits. Or, according to the BX thread I ran across, they were talking about the specs being 1600-1800. So I could see that I might be towards the lower end of my factory spectrum. But several of those guys were pushing it up to 1900 or 2000 psi. I didn't see anyone that had posted back negative results, only people that liked how it had pepped up their hydraulics. I'm not assuming at this point that these are the numbers for my tractor, just using them as a reference. Are you suggesting that this would be too much, or be risky? If so, HOW risky?

Maybe to relate a little better: I'm a diesel mechanic. A regular street type diesel pickup has, lets say, 300 horsepower. I add programmers all day, every day, that push them to around 500 horsepower. There is always a "risk" in doing this, obviously, otherwise the manufacturer would have provided them already programmed this way. But, you have to keep in mind that this manufacturer also has to warranty hundreds of thousands, or how ever many, of these trucks on the road, for 100K miles. So they derate them for this reason. I, along with many of my customers, run trucks like these, turned all the way up every day, with little to no issues. Possibly less life expectancy, but we are probably talking 150-200k miles down the road. Are we talking this sort of risk? Or are you closer to saying, the pump WILL blow? Lol.

 

[J_J]

Pumps have a test factor, but they are rated for a certain psi and volume. It would be difficult to say if an increase of 200, 500, 800 psi would damage a particular pump..

If your tractor is a new tractor, I would definitely keep it at the setting called for in the manual.

People are always tweaking things, but at a risk.

After the warranty runs out, then it is up to you as to how much to boost the psi for some more performance.

At 2000 psi, if you increase the relief to 2200 psi, you add a straight push force of 628 lbs x 2 = 1256 lbs

 

[Scott65]

That all makes sense. Except the last part. Would you mind explaining the push force?

 

[J_J]

Push force is the force developed by the cyl due to the pressure and the diameter of the cyl.

Hydraulic Force

Leave out the rod diameter for the straight on push force.

Insert the rod size for straight on retract force.

Set the calculation for 2000 psi, and then change it to 2200. The difference is what you will achieve by increasing the pressure by 200 psi over the factory specs. Double that for 2 cyl.

The calculation will calculate the push force at a certain pressure and cyl diameter.

You can play with the calculator and see why a log splitter uses a large cyl like 4 or 5 in and 3000 psi to develop 10 ton to 20 ton.

There are other formulas for pushing at an angle which most tractors do.