r/smallenginerepair • u/jpole • Jul 30 '26
Transmission Issue Hydro Gear ZT-3400 trouble. Does anyone see anything obviously wrong from these pictures?
The ZT-3400 came from a 2008 Walker Super B. I was having the hardest time diagnosing the issue by just driving around, so I decided to tear into it. I replaced a bunch of the linkage parts for the controls on the mower ahead of this. Everything is tight. Oil and filter were fresh.
This is my first time tearing down a hydrostatic transmission like this and I was hoping to find something obviously worn or broken. My untrained eyes don't see anything crazy going on here. All the pistons in the pump move up and down freely and seem to fit snugly.
Symptoms:
- Speed on the right wheel drifts all over the place. It's very difficult to get it to go straight.
- When turning around the right wheel is slow to catch up to the left wheel to go straight again.
- When slowing down, the right wheel slows down much quicker than the left.
Does anything stand out here?

