Hello, I have a problem with the transmission in my 580sm backhoe. I looked at all the posts I could find related to this issue and I still am a little lost and am looking for some advice. Here is the problem I am having. The trans will "slip" when pushing or when shifting gears on the move. Happens in both fwd and rev. It has the shuttle shift trans. I have been working on this issue for quite some time and I am very similar with these trans. Here is what I have done this far. New torque converter due to oil leak. Resealed the trans inside and out, transmission was completely different split. Inspected clutches and measure them to insure they are in spec. I have had the valve body apart about 6 times and everything looks good. I also tore the pump apart to inspect and that looked good as well. I checked the pressure coming from pump and that is in spec. When checking the pressure on the forward and rev clutch pack the pressure is slow/delayed to get to max pressure and sometimes won't reach max pressure, only 30- 50psi. I also replaced the plunger in which the solenoids are attached to. Is it common for the solenoids to become weak and not be able to overcome the spring and hyd pressure. Sometimes there will be no issue, but happens most of the time. Any help is greatly appreciated.
Sounds like the problem is a internal leak of some sort.Sealing rings,hard piston seals,Ect.Does that trans have a EPC (electronic pressure controller)?
No it does not have a epc.
Do you have the reverser with 4 gear selections by lever on the right side of the steering column? Case did have a powershift option and those are a different breed altogether. This answer is specific to the manual 4 speed transmission with a torque converter. It sounds like you have been pretty thorough in the reseal operation so we will assume no leaks internally and the fact that it does not go to system pressure all the time reliably indicates a problem in the modulation/relief valve circuit. A slight delay in the shift is normal and you should not get a snap when you shift, rather a slight pause then a somewhat smooth engagement. That is the result of the modulation piston in the control valve. The piston is charged by a small orfice so it does not slam to the other end of it's bore. this orfice is in the thin plate between the two gaskets in the cover held on by two allen head bolts. When the piston moves it compresses the relief valve spring pack to give a controlled pressure rise to the clutches. This is what is meant by "modulation". If you were to view the modulated pressure it should show a quick pressure rise but it will start with a slight low pressure then a quick controlled rise to full pressure. All system pressure is controlled at that bore by the innermost piston. Make sure also that the check ball, and spring are in good condition and the ball seat on the thin plate is in good smooth condition. We had issues with the inner snap ring in the control valve on a lot of units and there was a kit with a new style snap ring and gaskets to repair that. The ends would break off the snap ring and jam the relief valve piston from closing fully. If you have not inspected that area I would advise you to do so. A burr on that area at the snap ring could keep the piston from closing completely and not allowing relief pressure to be built. It does take a special installer to renew that snap ring as it is down in the bore. This would be the first place to look if I were you but there is a adapter to put on in place of the filter to allow a flo test to be done on the unit if you have to go deeper. A Case dealer should have that adapter and you may have to go that route to diagnose further if the problem is not found in the control valve. Thankfully, the valve is not that hard to remove and replace, the hardest part being disconnecting and reattaching the harness plugs. Let me know if you need to talk directly by sending your phone number to my private messaging and I'll call you. Mel
Mel please pm your number to me as being a new member it will not let me pm for some reason.