JD 790 300 loader

[JJZ 109]

OK, ordered my package today and it should be here tomorrow.
I downloaded the PDF from another spot on this forum and noted that one particular item has a red circle around it. Is this the only item to be installed? As has been noted earlier, I don't want to overdo it and tax the pump. Probably just whatever I need to do to bring it into the 24-2,500 psi range.

 

[dirt ditch]

OK, ordered my package today and it should be here tomorrow.
I downloaded the PDF in this thread and noted that one particular item has a red circle around it. Is this the only item to be installed? As has been noted earlier, I don't want to overdo it and tax the pump. Probably just whatever I need to do to bring it into the 24-2,500 psi range.

I dont know which PDF you downloaded so here is an expanded view. #8 is the factory shims you add to. Some of those small parts will stay inside the cap when it is removed. When I added shims to my 790, one shim dropped out of the cap as I lifted it off. Had to get a flashlight to find it. Cleaned it up, added new shims, put it back together, checked pressure. For no more work than it is, (10 minutes including finding a flashlight) it made a much more usable loader out of it.

 

[JJZ 109]

I dont know which PDF you downloaded so here is an expanded view. #8 is the factory shims you add to. Some of those small parts will stay inside the cap when it is removed. When I added shims to my 790, one shim dropped out of the cap as I lifted it off. Had to get a flashlight to find it. Cleaned it up, added new shims, put it back together, checked pressure. For no more work than it is, (10 minutes including finding a flashlight) it made a much more usable loader out of it.

Here is the PDF that I looked at. Looks just like your diagram.
Next question is how many shims to get the desired result without tearing up the pump further down the road?
Thanks!

 

[kennyd]

Here is the PDF that I looked at. Looks just like your diagram.
Next question is how many shims to get the desired result without tearing up the pump further down the road?
Thanks!

You NEED to buy a gauge and test for yourself...You CANNOT just do what someone else did! Saving the cost of a $30 gauge setup could cost you hundreds or thousands later-not to mention the safety aspect.

 

[JJZ 109]

You NEED to buy a gauge and test for yourself...You CANNOT just do what someone else did! Saving the cost of a $30 gauge setup could cost you hundreds or thousands later-not to mention the safety aspect.

Fair enough assessment. I've seen a few with 1/4" NPT. What would I use to adapt and where would I apply on tractor?

 

[kennyd]

Fair enough assessment. I've seen a few with 1/4" NPT. What would I use to adapt and where would I apply on tractor?

TSC (if you have one close) sells a 0-3000 PSI gauge for less than $20, plus a short piece of hose-the QD nipple can be had from JD for about $6.00 or so.

If you want to buy online I can refer parts from the Surplus Center.

Attached is a picture of my gauge-you just plug it into one of your loader ports, then you move the joystick to pressurize that port and observe the reading-that is your relief pressure. Take measurements before and after you add shims.

 

[JJZ 109]

TSC (if you have one close) sells a 0-3000 PSI gauge for less than $20, plus a short piece of hose-the QD nipple can be had from JD for about $6.00 or so.

I just so happen to have a TSC that I'll be passing close to tomorrow. Also will be at the JD dealer for some front end oil and the shim package. Heck, I think I even have an old hose or two in the garage from a past plow truck.

 

[foggy1111]

I looked at my shim package today....and there were 4 shims in the package (they were just stuck together). I think their are two (maybe more - didn't measure 'em yet) different thickness' of shims to allow for different pressure needs as determined by the gauge readings. I also got my coupler from John Deere and assembled the fittings to my guage as shown in the photos below.

The JD quick-coupler I got has an o-ring requirement....so I went to our local auto parts store and found an o-ring equipped fitting to attach to the coupler along with an elbow. Total cost of the guage ($14) fittings ($6) and Quick-Coupler ($10) is $30 plus change for mine. A pretty inexpensive way to gain about 20% improvement in hydraulic capacity.

I still need to assemble my guage with the sealant tape...so don't send the hydraulic/safety police after me.

 

[kennyd]

I still need to assemble my guage with the sealant tape...so don't send the hydraulic/safety police after me.

Just be very frugal with the tape, and keep it away from the first two threads-also make sure to wrap in a way that assembling the fitting wraps the tape tighter-NOT unwraps it.

 

[kennyd]

I just so happen to have a TSC that I'll be passing close to tomorrow. Also will be at the JD dealer for some front end oil and the shim package. Heck, I think I even have an old hose or two in the garage from a past plow truck.

Excellent!

 

[JJZ 109]

Just found a nice 18 or so inch piece of hydraulic hose in nice shape from an old Fisher plow.
Already stepped down to 1/4" on one and and the other is 1/2". Shouldn't be a very difficult plumbing job at all.
I always wondered if I'd have a use for that junk after I'd sold the old plow truck!

 

[foggy1111]

Just be very frugal with the tape, and keep it away from the first two threads-also make sure to wrap in a way that assembling the fitting wraps the tape tighter-NOT unwraps it.

FRUGAL is my middle name. Thanks for the tip.

 

[JJZ 109]

Just be very frugal with the tape, and keep it away from the first two threads-also make sure to wrap in a way that assembling the fitting wraps the tape tighter-NOT unwraps it.

I've got a can of pipe joint compound with Teflon. Would that suffice? The can states good for liquids up to 10,000 psi and -50 to +500º F. I'm guessing that it'll do just fine.

 

[kennyd]

I've got a can of pipe joint compound with Teflon. Would that suffice? The can states good for liquids up to 10,000 psi and -50 to +500ｺ F. I'm guessing that it'll do just fine.

Sounds like it will work...BUT this is just a gauge setup to be used intermittently, it's not being put into long-term service so...

 

[dirt ditch]

Adding shims will increase pressure to the whole hydraulic system of the tractor, not just the loader but also the 3 point.

 

[YesDeere]

Got the shims and gauge from the Deere dealer but the hose was back ordered. Still waiting. Was trying to go the easy route. Guess I'll be going to Colliflower (hydraulic hose makers). They are close to work and stock usually everything. Any one know what this will add to the weight limit on the three point?

 

[JJZ 109]

Guess I'll be going to Colliflower (hydraulic hose makers). They are close to work and stock usually everything.

I saw a Coll O Crimp stamp on one end of the Fisher plow hose that I'll be using. Leads me to believe that it's a hose that I may have had my local NAPA store make up for me several years ago.
It's good for 4,000 psi and I know I won't be approaching that. At least I'd better not be or I'll have worse problems to worry about!

 

[foggy1111]

I saw a Coll O Crimp stamp on one end of the Fisher plow hose that I'll be using. Leads me to believe that it's a hose that I may have had my local NAPA store make up for me several years ago.
It's good for 4,000 psi and I know I won't be approaching that. At least I'd better not be or I'll have worse problems to worry about!

From your earlier post on this hose: you stated that its 1/4" fittings on one end and 1/2 on the other. The 1/4" will fit the gauge....but I think you will need 3/8" on the other end to fit the JD Quick Coupler. I'm not sure how your going to do that with the O-ring fitting. Your going to need to add some type of double 0 Ring reducer or fitting adapter on the coupler end of the hose....or cut the hose and have the right fitting installed. FWIW

 

[foggy1111]

I (finally) added my shims today to increase the hydraulic pressure on my 790. I attached some photos below to show the gauge and pressure gain I got from 1 package (of 4) shims. Both of the gauge readings are at full throttle....photo 1 is before and photo three is after adding the shims. I had hoped to get a few more lbs of pressure....but I think its fine for now.

I have always been able to lift the front of my tractor with the loader...quite easily.....even at idle, and before adding the shims. Some have claimed they could not. I just got my tractor in December and have not had an opportunity to see it work in the field. So, time will tell if I add any more shims.

I had to pull the O-Ring from the cavity and slip it over the threads (as shown) into the groove located at the top of the threads. (its shown part-way up to that location in the photo below). Otherwise the O-Ring prevented re-starting the threads for me.

 

[JJZ 109]

From your earlier post on this hose: you stated that its 1/4" fittings on one end and 1/2 on the other. The 1/4" will fit the gauge....but I think you will need 3/8" on the other end to fit the JD Quick Coupler. I'm not sure how your going to do that with the O-ring fitting. Your going to need to add some type of double 0 Ring reducer or fitting adapter on the coupler end of the hose....or cut the hose and have the right fitting installed. FWIW

Here is what transpired today: The hose I am working with had a 1/4" NPT male swivel fitting on one end and a 1/2" NPT male fitting on the other.
As you state, the 1/4" NPT end of my hose did not exactly fit a JD male QC. The threads on an O ring fitting are slightly different. Luckily, a place that does hoses is 2 doors from my JD dealer. So as you also say, I had them cut the hose at the 1/2" end and crimp a new fitting on that would accept the JD male O ring QC.
We left the 1/4" swivel end intact and off to Tractor Supply I went to find a pressure gauge. I might as well have gone to a damned shoe store to find that gauge. The local TS sucks. No gauges and no staff with any knowledge of them.
So my next stop will be my local NAPA for a gauge. Will update when the shopping is complete.