990 Hydraulic Pressure Adjust

[johnbilt]

I have read the previous threads about adding shims to the pressure relief valve for the JD790, to increase the pressure to about 2500psi, for better loader performance.

I checked the 990 parts manual and see that it uses a different rockshaft case assembly. There are two valves with shims.

Has anyone attempted this for the 990 ? If so, do you have the parts number and info ??

 

[BGL990]

I'm also VERY interested in the answer to this question. My 990 is supposed to be delivered within the next 2 or 3 days (hope, hope .... /forums/images/graemlins/grin.gif) and a pressure boost to 2500 psi has crossed my mind as well. The 430 loader is used on the 4000 Ten series with a pressure of 2500 psi, so that isn't a problem, and I doubt a ~10% increase would hurt the pump or 3pt, so ......

I'll be ordering the service manual (on CD), so maybe that will help.

Brad.

 

[johnbilt]

Hi

I have researched this on the JD parts website. The JD790 has the valves mounted on the rockshaft case under the seat.

THe 990 rockshaft case is a different configuration. There is a valve on the top under the seat, and another valve on the left side of the case. JD offers a kit for each valve. P/N AM876765 fits the side valve; P/N CH13559 fits the valve on the top.

The JD990 side valve AM876765 part most closely compares to the shim kit for the JD790. However, the JD990 description calls out the top valve as the relief valve. Hmmmm.

I suspect both are relief valves. One may be a setting for the 3PH and the other an overall valve. This function is described a bit in the 790 discussions.

John

 

[BGL990]

Yes, it seems to make sense that there could be an overall relief valve and a separate one for the 3pt hitch. I have noticed a discrepancy between different 990 documentation regarding the 3pt lift capacity. Some (presumeably older) list it as 1500lb, and some list it as just over 2000lb. I wonder if all JD did was bump up the 3pt relief a bit?

A bit off topic - my salesman just called. My 990 will be a few more days because a mechanic noticed a small crack in the loader frame when they were prepping the machine. /forums/images/graemlins/mad.gif At least they are ordering a brand new frame section (one of the uprights I think) to replace it /forums/images/graemlins/smile.gif but it won't be here 'till probably Friday. /forums/images/graemlins/frown.gif

Brad.

 

[johnbilt]

Hi Brad

I'm sorry to hear your tractor was delayed, but glad they are taking care of you and getting it put together right. I have enjoyed my 990 very much and am sure you will also.

The 430 loader is quite capable. I can lift a full load of rock and dirt easily. The only time I stall it is when I am picking a load out of a pile. It would be nice to increase the pressure a little to get some extra performance. I would check it with a gauge to ensure I am not going over 2500. I'm not sure why JD limited it to 2050 at the factory.

I will do some more research and relay that to you if I get any more specific information. I'm interested in your info from the service CD when you get it.

Thanks for the reply !!
John

 

[BGL990]

Thanks back at you for any info you get! /forums/images/graemlins/smile.gif

I am planning to add some front AND rear hydraulic remotes to my tractor eventually. I have a local store, Princess Auto, that carries lots of hydraulic stuff for pretty reasonable prices. I am going to install the factory power beyond kit, and then plumb a bank of at least 4 valves, and maybe even 6 into this connection. Ideally I would like to be able to connect 2 extra cylinders at the front of the loader and 4 at the rear of the tractor (maybe tree shears and who knows what else at the front, TnT plus hydraulically angled blade plus ??? at the rear). Can't have too many hydraulics! /forums/images/graemlins/grin.gif

In any case, as part of all this extra plumbing, I figure I might as well include a pressure gauge as a permanent fixture. They are cheap cheap and if I'm doing all the plumbing anyway, an extra tee off the power beyond supply line is nothing.

Hope Muhammad has lots of disk space - there be plenty of pictures coming! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Brad.

ps. If you are interested, try www.princessauto.com I don't know if they ship to the US, but they do have a full catalog in .pdf form (with pictures) that you can peruse.

 

[GoodGuy]

Brad...
Would love to see your plans and of course any pics that you could post. I've been thinking along the same lines as yourself and I've got a Princess Auto an hour away that I've dropped more than my share of $$$.
Regards
Eric