DIY Kubota 3rd function MX4800

[Michael In Tennessee]

DIY Third function for Kubota MX4800.

Firstly, a couple of acknowledgements. Brian (MountViewRanch) @ Fit Rite Hydraulics for comments regarding flow rate of fittings I intended to use. LD1 for general knowledge and MX knowledge in particular. "Dave Knows How" on youtube who has an excellent series on putting a 3rd function valve on an L series as well as other Kubota based videos.

This is specific to my MX4800 tractor but is very similar to L series tractors and maybe others.

Parts list: I'll update over over time as I collect my receipts. The bulk of everything came from surplus center. The Northman SWH-G02-C6-D12-10 valve that everyone seems to like to use wasn't available, so I had to go with a slightly more expensive valve from Surplus center. I spurces a rear port D03 valve from ebay, but I probably wouldn't recommend doing this. It did provide areal clean installation, but you will see it was a slight challenge as we go through the build.

Surplus Center:

QTY 1 1/2" x 24" JIC 8F Swivel x JIC 8F Swivel SAE 100R16 Hydraulic Hose Assembly 4000 PSI Item Number: 940-2224 $13.95

QTY 2 3/8" x 96" JIC 6F Swivel x JIC 6F Swivel SAE 100R16 Hydraulic Hose Assembly 5000 PSI Item Number: 930-2296 $45.90

QTY 2 JIC 6M x 3/8 NPTF Bulkhead Connector Item Number: 9-2705-6-6 $5.20

QTY 2 JIC 6 Bulkhead Lock Nut Item Number: 9-306-N-6 $0.90

QTY 2 3/8 NPT Hex Nipple Item Number: 9-5404-6-6 $2.70

QTY 2 JIC 6M x 3/8 NPTM Connector Item Number: 9-2404-6-6 $2.40

QTY 2 JIC 8M x 3/8 NPTM Connector Item Number: 9-2404-8-6 $3.20

QTY 2 3/8 in Two Wire Dual Hydraulic Hose Clamp Item Number: 9-A2-18-D $6.90

QTY 2 3/8" NPT Hollow Head Plug Item Number: 9-5406-HP-6 $1.10

QTY 2 JIC 6 Cap Item Number: 9-304-C-6 $1.40

QTY 2 JIC 8 Cap Item Number: 9-304-C-8 $1.80

QTY 2 JIC 6 Plug Item Number: 9-2408-6 $1.50

QTY 2 JIC 8 Plug Item Number: 9-2408-8 $2.10

QTY 1 12 Volt DC 10 GPM OC DA Solenoid Valve Item Number: 9-6136 $147.10

QTY 2 Hirschmann Connector Item Number: 11-2457 $9.60

Subtotal: $245.75
Shipping: $21.15
Total: $266.90

Ebay:
DAMAN AD03SPB6P 1093 SUBPLATE VALVE $23.50 shipped.

Amazon:

Southwire 14 auge primary wire, 100% copper. Blue, Red, Black, 100 ft. each $58.28 shipped.

1/2" double split shaft collars (4) $10.00

Weatherpack connectors $17.00 Shipped.

Operators switch:

GAMA electronics P12001-3-MOM $34.95 shipped.

Steel:

$6 from local steel dealer.

Relays, fasteners, butt splices, etc were from my own stock, but were not expensive.

Lets start the build:

Hydraulics first:

I have a backhoe, so my power beyond on the FEL valve goes to my backhoe instead of the manifold under the right floorboard. It also has enough length and flex to be useful as the output of the 3rd function, so it was reused. Oddly enough, the input to the FEL valve is 3/8" JIC, but the output is 1/2". So, I used a 24" 1/2" hose with JIC fittings between the FEL power Beyond port and the P port on the D03 plate. The backhoe hose was used on the T port. 8 ft 3/8" JIC hoses were used to go up the FEL booms to the front of the loader.

The 3rd function valve was located below the loader valve. I used 3" wide 1/4" plate and made a tee that fit the spread of the loader valve attachment bolts and mounted the 3rd function valve as high as I could under the loader valve.



The cloverleaf holes are made with a 1" hole saw, just overlapped. The two small mounting holes were tapped 1/4-20 once I had the valve in hand.



The D03 subplate is installed. You can see the NPT to JIC adapters. It is a very tight fit. Here we also find mistake #1. I was too clever. There is no room to get a wrench around the flats of the hose nuts. well, almost no room. In fact, my OEM backhoe hose had wrench flats wider than the #8 JIC hose I got from Surplus Center. I had to go down to my local hydraulic hose maker and see if his fittings were a tab smaller. They were, so I had the OEM hose end cut off and replaced. That nut was between the sise of the 24" surplus center hose and the OEM fitting, but worked out. Barely. As I was wrenching that connection on, the corners of the nut would just tic by the other fitting nuts. Not a recommended practice. I suggest one source a more common side ported D03 plate and use 90 degree fittings.



Here we have the assembled valve and bracket.



And installed. You can see the wiring to the two Hirshman connectors you need for this valve. I've never used them before, but they actually make wiring easy. Also, if I wish to reverse the function of the thumb switch, I can just swap those two connectors.



Here you can barely see how tight those hoses are. I hope I have no future issues with this.

Hose routing:

Mistake #2: Take time to layout your hose routing and determining how long your hoses need to be. I did my measuring with the FEL on the ground not taking into account the service loop needed to raise the bucket. Thus, in the end, my hoses area tad too short and I might have to get longer hoses. Since I don't have an attachment to use yet, I'll wait to figure out that. Also, in your hose routing, make your hoses route near your boom pivot joint. Thay makes for the least movement in the hoses and ensures you don't have to manage much hose movement.

Hose routing was simple. Out the back of the 3rd function as shown above. Then up the FEL mounting bracket to the upper pivot and out the boom to the bucket. On the LA1065 FEL, you have two welded tabs for the OEM 3rd function installation. The Hose brackets I bought from Surplus center fit with a little modification. Discard the existing bolt and the metal bottom plate. Keep the top metal plate and replace the bolt with a 8mm x 1.25 mm x 50 mm bolt. Works beautiful. (obviously, double check bolt size if you have a different tractor.)



You can also see my hoses are a bit too short. The next length up would have been 2 feet longer, so I'll just wait and see what I need later. Also note I have not attached my bulkhead fittings and made a bracket for them yet for the same reason.

 

[Michael In Tennessee]

Electrical. Not as bad as I thought it would be. Note: I did not wire this to switched power. Its wired directly off the battery. So, it will cycle the valve with the tractor off. But, you have to push the switch, and with no hydraulic pressure, little risk.

I made a bracket to hold the switch relays. 1/8" x 1.5" steel. It slides under the radiator overflow and uses existing holes. Painted with Rustoleum medium grey 7786. Darned near a perfect match. Note: I suck at welding.



The wiring harness has 4 relays, but only two are used. Its pretty simple wiring. I use a constant power fused at 2 amps to go to the Joystick switch. Double pole momentary contacts power one relay or the other. Up is the "A" port, down is the "B" port. The load side of the relays is supplied from separate power fused at 5 amps. I found lots of relay wiring diagrams online to help figure it out. The other two relays can be used for other projects or, if I wish, to add a "power on" function for the 3rd function. It would be a switch you press once each time the tractor is started to energize the joystick switches.



Here we have the harness installed. My butt splice skills need some work too. I might cut them out and solder them.

The harness is routed up the plastic radiator shroud, then aft along the existing harnesses. I went to the auto parts store and got some wiring loom. I didn't check, but when I opened it up, I found it was not split. So, I had to put 6 wires through that tiny loom. Three times, as I forgot to do a couple of thing and had to remove the wires and do it over. I put a grommet in the radiator shroud. It took a 1" hole. Intimidating drilling a new tractor, but its done. Note: This is the only damage to the tractor in this installation.





Switch: Again, too cleaver for my own good. I made the switch removable since the 3rd function might not get too much use. I used weather pack connectors. I hadn't used them before, and they are a bit picky in terms of what seals you need for what wire sizes and Amazon ain't real good about telling you that. Its not wire size so much as insulation thickness. The wire I used has thicker insulation that some other wire, so you use the next size up seal. Also, the switch was wired with 10 gauge wire which is really unsuitable and I had to just make it work. I also suck at crimping these connectors and ended up soldering them.

I made a bracket to attach the switch to the joystick. The joystick is 13mm. I could not find 13mm double split shaft collars, so I bought 1/2" collars and sanded them over a 1/2" wood dowel to get them to fit. I also used the 1/2" dowel as a holding fixture to weld the collars to the bracket.

The switch I sourced from Gama Electronics. US made switch too! It is weather proof and comes with a housing, which made it a bit bulky, but simple to install. For $40, its a pretty decent solution. I was going to use a Polaris gear shift knob with winch buttons, but I had no idea if it would fit the 13mm joystick. I think I like this well enough.



Here is the bracket. I still suck at welding.




Bracket installed with switch.



From the operators station. Note that since the bracket is attached with shaft collars, I can rotate the switch above my knuckles and have it in a left/right orientation, or rotate it 180 degrees and operate it with my index finger. Who knows how I'll like it.

 

[Michael In Tennessee]

The parts above total to $420 or so. I've probably missed something and used some stuff from my own supplies, so maybe another $20 in miscellaneous. That is about half the land pride kit. Not too bad.

 

[TractorGuy]

Why use relays to switch 3.5 amps?

 

[LD1]

Why use relays to switch 3.5 amps?

Maybe switch wasn't rated for that?

 

[Gordon Gould]

An impressive project M in Tenn. Very nicely done and with a comprehensive report on it too.

gg

 

[Michael In Tennessee]

Why use relays to switch 3.5 amps?

Good design practice. You would do this for a winch or for off road lights. The switch I used is rated for 30 amps. But, if I don't like it or it isn't as robust as I'd like, the replacement might not be rated so well.