642B - violent bucking

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Active member
Mar 26, 2006
Have a 642B that I recently purchased. Stored inside in closed-in garage, supposedly for 2 years. Runs good - loader arms and bucket tilt work perfectly. Hydrostatics are strong - almost like they are getting over the recommended maximum 4000 psi of drive pressure. You can't control this thing. Slightest pressure on steering levers when trying to turn, go forward, or backing up, it goes crazy. I have had several Bobcats and rebuilt the hydrostatic pumps/motors and never, ever had one act like this. I searched the forum and one poster suggested to an OP who was having the same problem, to "shove the steering levers forward and he bet it would settle down. Try that with this one and it will literally "wheelstand" on the rear and "launch" like a missile. In just throwing out observations, something about the steering levers just doesn't feel right. You have to move the levers a tiny bit one way or the other to prevent it from "creeping", but once you find that spot, it will set right there with no movement. At this point, I will also mention that the slightest and I do mean slightest bit of pressure, the machine will move. Anything past that and it goes ballistic. Also, the levers don't seem to automatically return to "center" by themselves. I intend to take a look at the steering lever adjustment, on the side of the hydrostatic pumps, tomorrow. but my gut feeling tells me the problem is somewhere else. Any ideas? Thanks in advance, to all who might reply.


Well-known member
Sep 14, 2010
Do both sides respond the same? This usually is a indication of internal wear and eventually complete failure of a drive pump(s). It can also be extreme wear/play in the control linkage as well. If all the linkage seems tight, take the pumps apart and have a look.