Hi all, first post here, thanks for helping me out. Background: My Mannheim built JD400 backhoe loader has stopped going forward, reverse is fine. I've read there is an O-ring in near the forward clutch pack that fails. Believe I can test for this with compressed air through the lines that the reverser valve connects to. I still want to do things sensibly and test the pressures. Possibly relevant - the machine was also caught in the Lismore floods a year ago - so I've changed the hyd oil twice since. So my question is what are the threads on the JD test ports known as? I'm trying to figure out which adaptors I need to buy to connect to my test gauges. I won these gauges at an auction so know little about them. A Keller Leo 2 Mano 2000 and an IHS Australia gauge that goes to 1000bar 14k psi. They both have some adaptors up to a quick connect looking thing with threads about 1 & 1/8th and the inner dia is 3/4s. Any advice appreciated, cheers Dave
Welcome to HEF Daavvee ! I am not quite sure which it is, but those test port threads should either be a -2 or a -4 SAE O-ring port. I believe they are -2 (5/16 - 24 tread). Did you make sure the shift linkage is not worn and is in fact fully engaging? I'm not saying an O-ring couldn't have failed, but a common failure point on the forward clutch are the sealing rings and sleeve on the back side of the forward clutch drum. The pressure's are the next thing to check.
Thanks mate! So I discovered the ports on the JD are just m10x1.5mm thread bolts, worse case I can drill through one and weld on an adaptor