New owner JD 790

redmtnex · Jun 2, 2011

Howdy all! Just bought a 2001 JD 790 4x4 30HP with 360 hours, 7 backhoe, 70 loader with additional hydraulic grapple (think that's the name) and a box scraper R1 rear tires and not sure about the fronts, ag though. Used it a bit last weekend and am very happy! Its very clean and has extra controls for an auger or what ever. It has two cylinders for the 3PT. The backhoe is presently installed. This coming weekend I may attempt to take it off and try out the box scraper.
Anyhow I will eventually be looking for a tiller. Everyone around here is asking $800 plus for one.

So here it is, all my newbie questions!
1- What size tiller will this tractor handle?
2- Can any 3pt tiller be installed, pto compatibility etc?
3- My front tires are not real great and could be replaced, where do I buy them?
4- I read somewhere here about a shim mod for the loader controls, can someone point me in the right direction?
5- What about insurance, through my auto carrier or homeowners?
6- Aux lighting, I know that in normal light mode I can power additional lighting but where do I find that circuit, is there an easy plug in somewhere or do I have to hack into the wiring?
7- I would like to add some water ballast in the tires. Where do I get Calcium chloride and how do I get it into the tires?

Thanks
Greg

charleyfarmall · Jun 2, 2011

1. Personally I'd use a 5 foot tiller
2. Any 3pt tiller will work, but check to see what the gearbox rating is. King cutters are good economy tillers
3. There are several on line suppliers for ag tires, google is your friend. However, how are you going to get them installed? I'd look for a local ag tire store/ repair shop. If you have a good dealer, use them. Let them take care of loading your rear tires.
4. I don't know about the loader
5. homeowners.
6.Add your own circuit off the battery or starter, use an inline fuse. Search in the Customizing threads for Deere Lights. There may be a light kit available from the dealer that plugs in. Deere's auxillary kits aren't terribly expensive.
7.See #3. You can't do it without equipment, and you should use Rim Guard ( Rim Guard - Liquid Tire Ballast ). Your local Coop can do it and the tire change at your place even.

kebo · Jun 2, 2011

Here are links to two threads on it. If you search on "shimming hydraulics" in this JD forums, you will find several other threads on the subject. I added a shim kit to mine and upped the pressure to 2500psi. That is the max so don't exceed that. You will need a 0-3000 PSI gauge with the proper fitting to measure the before & after pressures. I don't have the JD part number for the shim kit handy, but I know it's mentioned in some of the threads already. It's an easy mod to make and well worth it.

http://www.tractorbynet.com/forums/.../134666-long-term-effects-790-hydraulics.html

http://www.tractorbynet.com/forums/john-deere-owning-operating/36404-790-lift-capacity.html

YesDeere · Jun 2, 2011

Good answers so far. I used a five foot tiller with no problem. Once hooked up to a six footer and it didn't like that. As far as shims go. It is well worth it. Don't go too high with it. One pack of shims will do. There is a detailed thread with pics and part numbers. Just search

redmtnex · Jun 2, 2011

Thanks everyone for the replies.
In my operators manual it states for light position "C - (Field Position) Headlights, taillights, and any optional work lights ON. The other positions do not mention optional lighting. That leads me to believe that there is a wired harness circuit already in place in which to run aux lighting. There is a fuse (4th position) specifically for flood lamps. Besides a service manual is there anywhere I can obtain a wiring schematic? I will look around for unused harness plugs and do some testing.

YesDeere · Jun 2, 2011

When I put lights on the rops of mine, I used an unused plug by the left rear fender. Only rub was the rear work lights were only on when the headlights were on. Easy to do though. No real good way to hide the wires for a clean look.

redmtnex · Jun 2, 2011

YesDeere said:
When I put lights on the rops of mine, I used an unused plug by the left rear fender. Only rub was the rear work lights were only on when the headlights were on. Easy to do though. No real good way to hide the wires for a clean look.

I think that wire is explained in this tread http://www.tractorbynet.com/forums/john-deere-owning-operating/134613-jd-790-what-connector.html with a schematic. I think for my purposes I will not be using the built in circuit. Reason is I may not always want the ignition switch in the run position to have aux lights on. My solution will be two circuits, both powered via light relays, the relay being activated from a couple of switches on the dash. Only problem with this setup is someone might turn on the lights accidentally and drain the battery. A solution to that would be a second key switch to safeguard those circuits. Main power will come directly from the battery, fused of course. The use of light relays eliminates having to run heavy gauge wire to the switches.

RoyJackson · Jun 2, 2011

YesDeere said:
When I put lights on the rops of mine, I used an unused plug by the left rear fender. Only rub was the rear work lights were only on when the headlights were on. Easy to do though. No real good way to hide the wires for a clean look.

I think Deere's thoughts were, if it's dark enough to use the work light, it's dark enough to use the headlamps.
There is a pigtail (under the seat, if I recall) specifically for the rear work lamp. If you buy the Deere worklamp (about 40 bucks), it'll plug right in. There are also holes (just aft and inboard of the flasher lamps) in the fenders to mount the worklamp.

See the attached .pdf file for shimming the pressure relief valve.
Couple hints:
Don't go overboard shimming the valve...one shim kit is quite sufficient.
When removing the cap (circled), watch out for the spring and othe small pieces popping out...these fly pretty easily. I strongly suggest you do this job with the tractor parked on a nice clean floor.

redmtnex · Jun 2, 2011

Thanks Roy for the pdf. I ordered the shims and the rubber bumpers for the 7 backhoe. Believe it or not I can not find anything else in need of replacement. I did though order the brackets to mount the SMV sign onto the backhoe. Ordered the sign on eBay for real cheap! You all have been a great help, thank you very much! I will build a gauge to check that final pressure but it will be a few days out before I get to that. We are getting ready to do a kitchen remodel and the county is making us upgrade our septic system Just found out today that I have to add 140 feet of leach field. The 790 is here just in time! :thumbsup:

YesDeere · Jun 3, 2011

When I put those lights on I took the path of least resistance. The double blizzard two winters ago was bearing down on us and I wanted lights. Mainly so I didnt hit anything while clearing a lot. It worked for that and woodsplitting later on.

I think your going about it the right way. On my 4310 the light switch works without the ignition on. That is nice.

About the leach field. My 790 had the #7 hoe as well. Very good for what it is. The new to me 4310 has the 47 hoe on it. Just a bit beefier. But still a kick in the a** to dig a field with it. I did about a 125' field with it and was on that thing the better part of a weekend. The guy I know who sucked my tank out before I started had a good laugh when I told him I was going to dig with the Deere. Said I'd be all weekend. I was. Oh well I told him that's all I have. Got it done but if I had to do it again there would be a mini ex rented.

Just saying...

YesDeere · Jun 3, 2011

Forgot to put the proof pic in

redmtnex · Jun 3, 2011

YesDeere said:
About the leach field. My 790 had the #7 hoe as well. Very good for what it is. The new to me 4310 has the 47 hoe on it. Just a bit beefier. But still a kick in the a** to dig a field with it. I did about a 125' field with it and was on that thing the better part of a weekend. The guy I know who sucked my tank out before I started had a good laugh when I told him I was going to dig with the Deere. Said I'd be all weekend. I was. Oh well I told him that's all I have. Got it done but if I had to do it again there would be a mini ex rented.

Just saying...

I am prepared for the long haul! Only thing is I have a 9" and a 14" bucket both with big gnarly teeth. The trenches I need to dig will be 36" wide 2 foot or less deep if I go with an infiltrator system, 18" wide by 4 foot deep if I go with a standard pipe and rock system. No rock or dirt to get rid of with the infiltrator system. My soil is soft non compacted so perhaps a wider bucket with a knife edge would be better than the gnarly teeth 14 inch-er.

RoyJackson · Jun 3, 2011

YesDeere said:
Forgot to put the proof pic in

Boy..that's a heck of a slope you're working on...with the ROPS down too!!
I mean..it's so steep, the houses are built on an angle!

kebo · Jun 3, 2011

redmtnex said:
I will build a gauge to check that final pressure but it will be a few days out before I get to that.

Here's a pic of the one I fixed up. The gauge was like $19, and the quick disconnect fitting and the adapter for it were about another $8 I think. Just remember when you check your pressures, you will want the engine rpm's to be pretty much maximum so you are seeing the most PSI the pump will deliver.

redmtnex · Jun 3, 2011

kebo said:
Here's a pic of the one I fixed up. The gauge was like $19, and the quick disconnect fitting and the adapter for it were about another $8 I think. Just remember when you check your pressures, you will want the engine rpm's to be pretty much maximum so you are seeing the most PSI the pump will deliver.

I am assuming the fitting is not a hardware item, so where can I obtain one? And good point about the RPM. Which reminds me that the tension nuts on the manual throttle arm needs tightening as the rpm drops off on its own. Its been raining almost every time I get a chance to go out and tinker. June and its still winter here in the Santa Cruz Mountains of California. Supposed to get even more rain over the weekend.

On another note we brought in a 30 yard dumpster last weekend and I had planned to be able to drive some stumps into the back of the dumpster with the 790. Turns out the ROPS extension was to high and would not clear the upper door/wall brace of the dumpster. I did not measure if it would clear with the extension removed as at that time I had the 790 for just one day and had no clue that there was an extension in place until after I found this site and all the info on the 790's. I still have a rotted 150 foot long two foot diameter douglas fir on the ground that needs a dumpster ride. Hopefully I will be able to take out the extension and sail under the brace next time. I suppose its advisable if I drop off the backhoe that I should carry the box scrapper for ballast??

kebo · Jun 3, 2011

I think that a JD dealer can provide all the parts needed to build your gauge, but I bought my stuff from a local hydraulic repair shop. You may/may not have a hyd shop near you, but check around and see. If not, you can always order the parts online but you pretty much have to know exactly what to order then. I don't have the part number for the quick connect fitting I used, but maybe some else here can provide it?

If you do drop off the BH, you will need some ballast. The boxblade should be sufficient, but if you pick up a large chunk of wood and the back end gets light, you will know it! If so, just add more weight by whatever means you have. One quick, dirty, cheap way would be to strap down a 35 gallon drum on the boxblade and fill it with water.

I am confused on one thing though..... you refer to the "extension" on the ROPS. Do you mean the top piece on the ROPS that bolts to the two upright pieces?? If you remove that, you pretty much can't count on the ROPS to do it's job should you do the unthinkable (rollover). That's an integral part of the ROPS structure, but I understand sometimes you just gotta do what you gotta do!

charleyfarmall · Jun 3, 2011

The 790 is a great tractor and will serve you well.

RoyJackson · Jun 3, 2011

kebo said:
.
I am confused on one thing though..... you refer to the "extension" on the ROPS. Do you mean the top piece on the ROPS that bolts to the two upright pieces?? If you remove that, you pretty much can't count on the ROPS to do it's job should you do the unthinkable (rollover). That's an integral part of the ROPS structure, but I understand sometimes you just gotta do what you gotta do!

The 790's ROPS has two extensions (one on each of the vertical sections) about 10" long. These are installed on the ROPS if the tractor has a backhoe. IIRC, it has something to do with clearance when that #7 'hoe is being mounted (the standard ROPS is too short and cranial injuries can occur during the mounting operation (operator is on the backhoe seat)).
So, redmtnex isn't writing about the top horizontal bar on the ROPS.

redmtnex · Jun 4, 2011

kebo said:
I am confused on one thing though..... you refer to the "extension" on the ROPS. Do you mean the top piece on the ROPS that bolts to the two upright pieces?? If you remove that, you pretty much can't count on the ROPS to do it's job should you do the unthinkable (rollover). That's an integral part of the ROPS structure, but I understand sometimes you just gotta do what you gotta do!

Roy is correct. I have the extensions that raises the horz bar for backhoe use. I would take out those extensions when the BH is off and fasten the horz bar back onto the uprights as my property is far from bing level.

The 35 gal drum is an excellent idea. I just happen to have a couple lying around!

YesDeere · Jun 4, 2011

RoyJackson said:
Boy..that's a heck of a slope you're working on...with the ROPS down too!!
I mean..it's so steep, the houses are built on an angle!

Well Roy. You caught me. The first owner damaged the top bar for the rops. So I've never had it. I know I know. I'm being not only cheap but stupid. Let the safety police stoning begin:-(