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Chris: I am trying to correct some hydraulic problems with a 460. I am a rookie at these systems, but disassembling the control/relief block on the 460 this past weekend I think qualifies me to help you out a little. The relief valve is located in a "block". This block is under the remote and fast hitch spool valves-the ones where the control lever attach. The block is mounted the the left-side pedestal casting that holds up the control valves and dash.
Remove the sheetmetal piece that the brake set pull rod attaches to, and you will see all of this. From what I have seen on Saturday, it appears the relief valve is non-adjustable. There is no screw type or threaded adjuster. Perhaps a stiffer relief valve spring is avaiable. This will allow the system to generate a higher pressure that you need before the pressure is relieved or 'dumped'. Perhaps the relief spring can be shimmed, but from what I saw, this doesn't seem to feasible. I would caution anyone in attempting to jack up hydraulic system pressures. It could be that the existing relief valve spring is sacked out--weaker than factory specs and dumping the pressure too early. I think the manual spells out a correct length for the spring and a pounds of resistance to compresss the spring a certain distance. I see in your post that you checked the pressures so a weak relief spring is not the case. Another option is changing the lift cylinders on your loader to ones with larger bores. More piston area = more force.
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