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!