Hey y’all. I got a case 580l with the carraro Shuttle shift. When it’s not fully to operating temp it shifts in and out of forward and reverse like its brand new but when it gets hot and you are working it hard it hesitates to shift into reverse In all the gears. At first it will be slight but it progressively gets worse. It completely went out when one of my operators was running to so I checked the coil solenoids and the back one didn’t have any resistance so I ordered one and while I waited I took the valve body off and checked everything out and the retainer snap rings looked good except one didn’t have the holes to take it out but it was holding so I left it alone. The plunger that to two coils go on was really stiff so I went ahead and replaced that top figuring it was prolly what burnt the back solenoid you. So I get it back together and it works great until it gets hot and then it hesitates but still goes in eventually. Another thing I’ve noticed is if it goes in you can put it in reverse over and over and it locks right up but if you put it back in forward then switch it back to reverse it hesitates. If you have any ideas or suggestions I’d be glad to hear them. Thank!
My guess is - 1) that there is excessive clutch pack clearance, perhaps with a little too much oil leakage past the piston seal. 2) OR the charge pump is a little tired & not delivering enough oil flow - to push the reverse piston & lock up the pack. Problem could be either one of these or even a combination of both problems. Some transmission pressure tests should be the first thing you should do. Keep in mind that once Reverse has engaged (& continues to engage) the pressure readings will probably look like they should. It should be interesting to compare readings with cold oil then hot.
Thank you for replying. Do you have an idea as to what the pressure numbers are in normal operation?
The pressure you're asking about should be 250-300psi at operating temp. There are different ports to check pressures on control valve. One for each clutch and one for pump pressure and torque converter pressure. The threads are metric o-ring boss, so be careful on screwing anything into the ports. Have you checked the regulator piston on the control valve? Carrao had a problem with the early snap rings breaking the ears off and getting lodged in the piston, but usually the machine wouldn't move at all or be real slow.
Yes I have check the snap rings in there. One side was a normal black one with the and had the ears one it and the other side it looked chrome and I didn’t see no ears on it and it almost looked as though it was made into it and I didn’t see a snap ring groove anywhere
Let me take the valve body back off and I will post some pictures
Here's some technical help with regards the testing
Update. I changed the oil so I could look at the sump filter and filled it back up and put a gauge on the m4 port. It’s reading right at 11 bar like it’s supposed to. Ran it real hard and got it hot and it’s still hesitates but not as bad. It don’t pressurize til it goes fully in gear thought. Kinda leading me to beleive maybe the valve that the coil plunger operates is maybe sticking?
Could it be a slow to react Shuttle Time Delay relay in the fuse panel?
Hmmm...... thicker new oil may help a tired charge pump perform a little better too...... Re the pressure reading not showing till it engages makes total sense - what you expect to see.
The relays seem to be functioning right. How can you tell if the charge pump is going bad?
The proper way is to use a flow meter & you will need an adaptor which connects to the transmission in place of the oil filter..... not your everyday tools.... Apart from that you just have to be brave & pull the transmission to have a look......
Well I appreciate y’all’s help! It’s going in even with the hesitation now so I will let it limp along for now. We do more trenching than spoil moving so maybe it’ll hold up long enough to get through this busy time. Thanks for the help!