Wondering about this problem: 644C was working fine until the last time I shifted into high range, the transmission pressure gauge went to zero. Normally, the guage drops pressure when you shift, but quickly recovers. Low range still does this, but when you shift into high range the guage goes to 0 and stays there. I could still move forward in high( if I wanted to risk it). Anything to look for short of pulling the tranny?
The piston that controls your high range clutch has failed and there's not much you can do without pulling the transmission. More than likely, you will have to have the transmission gone through and at least have new seals and gakets put in, along with replacing the piston. We rebuild these transmissions for around $7000.00. It would also come with a 1 Year/2000 Hour Warranty. Or we could also do a cheaper repair of your transmission. Let me know if your interested. Thanks, Kyle Centranz, Inc. 816.650.3161
...or you could articulate the machine to the right and remove the floor and remove the front cover from the transmission(the side facing the front of the loader). Might have to remove the park brake also. The high range clutch is accessible right under that round cover. The pressure port is routed through the transmission case through a port on the front cover and into the high range clutch pack. It's about the only thing that you can get to on those transmissions while still in the loader.
Good info to have Jonathan.Will this also work on B modles or are things different.
The "A" "B" "C" and "D" series Deere loaders have that style Allison transmission.. So the procedure would be the same. The part numbers change according to size/age, but its the same basic design. The newer they got , the harder they were to access any part of the transmission it seemed.