790 and 3005 Hydraulic Shimming

[RoyJackson]

790 and 3005 Hydraulic Shimming:
This is posted in response to a TBN member's PM to me.

This is for a 790, but the 3005 is virtually identical.
Don't go overboard on the shimming!! One kit is sufficient.
I didn't have any gages to read hydraulic pressure, so I went with a seat of the pants feel. There's an improvement, but it's not going to make a 3005 into a 10 ton front end payloader. Be realistic in your expectations

 

[Tractor Pilot]

And a JD 770!

 

[foggy1111]

Like Roy, I added one pack of shims and boosted my pressure by about 10%. After using the tractor and loader a while, I decided I didnt need more lifting power with the tractor and left well enough alone. I could have gotton another 10% and still been within "normal" hydraulic PSI spec's...but it is such a well balanced rig the way it is (was) and why "overdo" it?

I did use a guage to check pressure.....and while I coulda added more shims....why not enjoy the great design capabilites of this little brute....and not overdo the loader, etc.? Mine picked up everything I wanted it to.

I'd still have that 790....if I didnt need a grapple and a need for a hydrostatic tranny for precision loader and stump grinding work. (Shifting gears is not in my DNA.) Great little tractors tho. :thumbsup:

 

[RoyJackson]

I'd still have that 790....if I didnt need a grapple and a need for a hydrostatic tranny for precision loader and stump grinding work. (Shifting gears is not in my DNA.) Great little tractors tho. :thumbsup:

Shifting gears is in my blood, but the only thing I didn't like about me 790 was reverse...reverse, low range was way to slow, reverse high range (both at PTO RPM) was way too fast.
I went for another tractor for the reverser transmission. If I can't do it with 12 gears...then I flat out can't do it!

 

[Tractor Pilot]

The JD 770 tech manual says low reverse is 0.8 mph and high reverse is 3.4 mph.

I used to think the low reverse was too slow even at PTO RPM until I got my 60" 3-pt snowblower. I like that speed a little better now when using just that implement. But overall, the low reverse is too slow and the high reverse is too fast.

I shimmed my JD770 too. I noticed a difference. This mod is well worth the $2-3 for the shim pack and the 1/2 hr it takes to install them. Attached is another file I found on the net on how to shim the hydraulics on these tractors (I'm not the author). Like Roy advised, use one shim pack max. That should put the pressure around 2500psi. I wouldn't recommend going above 2500psi. I set my tractor to about 2350-2400psi.

 

[jwinner]

I did the shim modification to my 790. Used it about four years like that before I sold it to buy the 4005. I did not have a way to test the pressure so I did what had been suggested - add just one pack. One pack increased it enough for me, and I felt that any more would just be too much for that size and weight tractor.

As an FYI, I also shimmed my 4005. I was a little irked that even with a 300cx loader I wouldn't have the same lifting capacity as a 3000 twenty series. This time I built a gauge and added enough to make 2500psi. Have only used it like that for a few months, but seems to be fine. Wasn't sure what the pump was capable of - there was an odd line in the specifications that said the pump operating pressure range was 2400-2700 psi. From the factory it is set at 2200 I think. I guess if that's true I could have went more, but who knows...

 

[Willl]

I bought the gauge setup and pack of shims right around the same day.

Gauge said it was already slightly over rated pressure so the shim pack is still in my tool box.

I'll live with it.

 

[Jamming]

HUH ! Why do this ? mine picks up a full bucket of gravel and seems strong to me, but maybe i lower expectations.

 

[RoyJackson]

HUH ! Why do this ? mine picks up a full bucket of gravel and seems strong to me, but maybe i lower expectations.

No, not lower expectations...just new to the tractor world.
Tell ya...when I shimmed mine, I can't say I really needed more capacity or I was dissatified with my tractor. I had no real reason to shim it...just wanted to.

 

[Jamming]

I see ! Doesn't this mod put more strain on the whole system or is it made to take it ?