xpack, I don't know if you've seen this or if it helps but here is another similar situation from a different site:
I'm the proud owner of a 1974 Case 580 CK backhoe [power shuttle] She's old, she's ugly but she runs great.
Lately I've noticed that if I don't warm her up for at least 15-20 minutes, she won't move. The clutch doesn't engage until she's warm.
Is there any adjustment I can make so she would grab faster? Once she does grab, she's OK from then on.
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When trouble shooting any problem, start with the simple things first. Example: If an alternator is not charging, check the alternator drive belt first. Also, you are well advised to purchase a “Service Manual” from a Case Industrial dealer. While it is not cheap, the trouble shooting guides and illustrations make it worth every dollar.
There are two types of power shuttle drives used by Case for the 580, Twin Disc and Rockford. Trouble shooting both are basically the same.
With clean oil, filters, proper oil level, and clutches are NOT transmitting full power:
1) Lubrication valve stuck open a. contamination or wear in spool area causing hang up. b. regulating valve spring broken or improper tension. c. poor register between clutch hub and piston carrier.
2) Clutch dump valve stuck open a. contamination or wear in spool area causing hang up. b. regulating valve spring broken or improper tension.
3) Low oil pressure a. worn out or malfunctioning oil pump. (180 psi engagement) b. clutch pressure regulating valve out of adjustment (40 psi lubrication)
4) Piston outer sealing rings scored or wedged in piston grooves – oil contamination.
5) Oil pressure NOT being applied to the whole piston area – contamination in the oil transfer orifice holes between the primary and secondary clutch piston areas.
6) Opposing clutch NOT dis-engaging when shifting to the other – opposing dump valve and lubrication valve stuck closed.
The converter and lubrication oil regulator valve is located near the center of the torque tube cover and is held to the cover by two bolts. The converter oil temperature sensor is also located on that regulator valve. The valve spool is in that small casting behind a snap ring and retaining plug. The spool MUST move smoothly in the bore. The valve spring (uncompressed) should measure 1.375” and have 10-12 lbs. pressure at a .75” (compressed) height.
The clutch pressure regulator valve is located between the two spools on the control valve body. The regulator valve spool is behind a screw-in plug with shims to adjust the clutch pressure. The spool MUST move smoothly in the bore. The (uncompressed) length of the clutch pressure spring should be 2.04” and have 45 lbs. at 1.344” (compressed) height. The clutch pressure should be at or near 180 psi. There is an oil pressure test port (pipe plug) located on top of the control valve. Adding a .0209 shim will increase pressure by 5 psi. A .0418 shim will increase pressure by 10 psi. Likewise, the removal of a shim of each specific size will reduce pressure by the stated amount.