Kubota bx pressure relief valve testing + adjusting

beex

Member
May 21, 2019
312
5
18
on my bx
Setting the relief valve to over spec is a dumb idea for multiple reasons that should not need explanation and should not be recommended on this forum.

If you need more lift capacity than your tractor has, get a bigger tractor.




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Dave_eng

Well-known member
Lifetime Member

Equipment
M7040, Nuffield 465
Oct 6, 2012
5,108
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Williamstown Ontario Canada
From the other forum..... tale of an owner who thought adjusting a BX relief valve was always simple.


Bought one of those hydraulic pressure gauges with a shim kit. My less than 100 hr BX23S was reading 1750PSIG so I was going to add the 0.2 mm shim to bring it up 80PSI more. Took off the cap, installed it and retest showed 2500PSIG. Tried it with the stock shims and still 2500PSIG. Took out all shims and got it to go down to 2300PSIG so the relief is functioning. Checked the gauge, its good. Everything inside the relief moves easily,spring ,poppet, except the relief valve seat. Won't budge. I ordered a new one to see what I'm up against. Didn't get it yet. The original must of moved when I first disassembled it and I drove it in to far or cocked when re tightening it, their are holes on the side of the seat cage that don't exactly alien with the drain hole in the casting. First is 2300PSIG to much for this tractor? Maybe the spring is to tight and the cap just wasn't that tight from the factory. File the spring? I have no clue how to get the seat out other then try to thread a bolt into it and pull, or carefully drilling it out, thus destroying it. I'd appreciate any advise because I'm very meticulous they way I take care of my equipment,boats, cars, etc, and this is kind of embarrassing.

His final words:

Seat is in there tight. Tried everything , can't get it out. Took 1.016MM/.040 in off the spring. I have 1850 psig hot now. Wasn't worth the hassle for a hundred pounds.

Dave
 

NoBiffBetter

Member
Oct 30, 2018
193
7
16
Silver Creek, NY. USA
From the other forum..... tale of an owner who thought adjusting a BX relief valve was always simple.





Bought one of those hydraulic pressure gauges with a shim kit. My less than 100 hr BX23S was reading 1750PSIG so I was going to add the 0.2 mm shim to bring it up 80PSI more. Took off the cap, installed it and retest showed 2500PSIG. Tried it with the stock shims and still 2500PSIG. Took out all shims and got it to go down to 2300PSIG so the relief is functioning. Checked the gauge, its good. Everything inside the relief moves easily,spring ,poppet, except the relief valve seat. Won't budge. I ordered a new one to see what I'm up against. Didn't get it yet. The original must of moved when I first disassembled it and I drove it in to far or cocked when re tightening it, their are holes on the side of the seat cage that don't exactly alien with the drain hole in the casting. First is 2300PSIG to much for this tractor? Maybe the spring is to tight and the cap just wasn't that tight from the factory. File the spring? I have no clue how to get the seat out other then try to thread a bolt into it and pull, or carefully drilling it out, thus destroying it. I'd appreciate any advise because I'm very meticulous they way I take care of my equipment,boats, cars, etc, and this is kind of embarrassing.



His final words:



Seat is in there tight. Tried everything , can't get it out. Took 1.016MM/.040 in off the spring. I have 1850 psig hot now. Wasn't worth the hassle for a hundred pounds.



Dave


I hear your concerns/. First iv heard of it.. I’ve adjusted my bx pressure MANY times just playin with it testing lift capacity’s along the way.. I’m confident that the person you just posted messed something up or just had some super bad luck.

Iv been a mechanic most my life working on vehicles for half and big equiptment and tractors for the other 1/4.. I’m glad you posted this so people who are thinning about trying it can be cautious.

Just showing the people who ARE going to do it how to do it and want them to be safe when they do turn it up by adding proper ballasting as I mentioned many times in my video and explained.


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NoBiffBetter

Member
Oct 30, 2018
193
7
16
Silver Creek, NY. USA
Setting the relief valve to over spec is a dumb idea for multiple reasons that should not need explanation and should not be recommended on this forum.

If you need more lift capacity than your tractor has, get a bigger tractor.




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For 1. i it’s my tractor, for 2. I know the risks and don’t care.. I got 5k total into the entire tractor and loader if something breaks I’ll fix it, to me it’s worth the risk, I’m not buying a 10-20k tractor for a little more lift when I don’t even need that much lift to begin with.. increasing your pressure slightly above spec ain’t gonna do nothing and I’ll tell you why.. the hoses, fittings, cylinders, front axle.. and more are all able to handle it and Carrie the load.. the reason Kubota turns down their pressure so low compared to competitors is because the bx is much lighter than say that of the John Deere 1025r or 1023e... the reason Kubota makes theirs light is to be competitive in a market where most people wanna use these tractors for mowing their lawns and doing residential work as well as landscapers who wanna trailer them around with out having to have a tandem axle teller or anything real heavy duty... because the bx is so light in the rear Kubota turns down their pressure in order to keep customers safe who will not ever put ballast on the rear of their bx... this is a liability thing.. for people who DO use the tractor as a TRACTOR and load the rear end up with 300-500lbs of rear ballast THEY want more lift power.. and not thousands more hundreds more.. and to easily do this you turn up the relief pressure.. that’s it.

Iv had my pressure up for Over a year and I over work my bx CONSTANTLY.. I stress it out almost weekly and it handles it like a dream, no leaky cylinders no blown lines no nothing.. iv talked to guys on this forum alone who said they’ve had their pressure at 2200lbs for Over half the tractors life! And they STILL haven’t seen an issue..

Obviously all of this is going to depend on how you use your tractor how you care for it and how much risk your willing to take, that’s why you need to leave it to the person who owns the tractor to decide and not jump down somebody’s throat about “OMG that’s over spec” NO SH*t it’s called Kubota being conservative.


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North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
28,306
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Sandpoint, ID
For 1. i it***8217;s my tractor, for 2. I know the risks and don***8217;t care.. I got 5k total into the entire tractor and loader if something breaks I***8217;ll fix it, to me it***8217;s worth the risk, I***8217;m not buying a 10-20k tractor for a little more lift when I don***8217;t even need that much lift to begin with.. increasing your pressure slightly above spec ain***8217;t gonna do nothing and I***8217;ll tell you why.. the hoses, fittings, cylinders, front axle.. and more are all able to handle it and Carrie the load.. the reason Kubota turns down their pressure so low compared to competitors is because the bx is much lighter than say that of the John Deere 1025r or 1023e... the reason Kubota makes theirs light is to be competitive in a market where most people wanna use these tractors for mowing their lawns and doing residential work as well as landscapers who wanna trailer them around with out having to have a tandem axle teller or anything real heavy duty... because the bx is so light in the rear Kubota turns down their pressure in order to keep customers safe who will not ever put ballast on the rear of their bx... this is a liability thing.. for people who DO use the tractor as a TRACTOR and load the rear end up with 300-500lbs of rear ballast THEY want more lift power.. and not thousands more hundreds more.. and to easily do this you turn up the relief pressure.. that***8217;s it.

Iv had my pressure up for Over a year and I over work my bx CONSTANTLY.. I stress it out almost weekly and it handles it like a dream, no leaky cylinders no blown lines no nothing.. iv talked to guys on this forum alone who said they***8217;ve had their pressure at 2200lbs for Over half the tractors life! And they STILL haven***8217;t seen an issue..

Obviously all of this is going to depend on how you use your tractor how you care for it and how much risk your willing to take, that***8217;s why you need to leave it to the person who owns the tractor to decide and not jump down somebody***8217;s throat about ***8220;OMG that***8217;s over spec***8221; NO SH*t it***8217;s called Kubota being conservative.


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Let me start with a polite "Dial it back" comment.

If your going to follow things by specs and standards then your golden, but your not, be prepared for the negative / corrective comments.

You need to dial the quick negativity back a lot.

You are making video's that go against the grain and against specs and against warranties.


Your point is it's your tractor, and I'll do whatever I want, Yea that's fine, but your encouraging others to follow your path, and that's the sticky point.

I 100% agree with beeX's position that bumping pressures up to make it lift beyond the specs of the loader are dangerous.
And if your doing that, you probably should get a bigger tractor!

On your video you made some mistakes:

The gauge is glycerin filled not water.

The PSI of the hoses is the burst pressure, slide the hose protector back and read the PSI on the hose.
The fittings they use are also to used to spec, and bumping the pressure up that high can cause them to drastically fail.

This is a BIG point, Adding ballast to make up for making the loader being able to lift more weight WILL NOT take any strain off the front axle, weight in the bucket is weight.
The strain is there and also on every other component in the system.
 
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beex

Member
May 21, 2019
312
5
18
on my bx
Correct, I don’t care what the PO does to his tractor, and he pointed out he doesn’t either. But the tone of the initial post was “look at this, this is cool if you want to do this, this is how, no problem, just add ballast”

My criticism is you should not encourage others to over pressure the hydraulic system. Lots or even most people that read these threads are here to learn because they are inexperienced, that’s why they are here, and that’s the primary purpose of the forum: learning. And for the most part they do care what they to their machines. This isn’t something that should be taught.




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