I need some help diagnosing this

[MikePA]

I have a ZT mower with ZT2800 transaxles. It can get a little jerky under certain conditions and I thought it would be a belt, but now I'm not so sure.

• On pavement, there is no jerkiness at any speed, although the right side is clearly slower than the left.
• on grass, beyond a reasonable slow speed, the mower can become jerky. This seems to be controlled exclusively by slowing the left side.
• It can operate in reverse at any speed with no trouble.
• it can pivot in either direction with no trouble in rev or forward.
• The right side requires noticeably more forward movement when mowing. In fact, it feels like I'm barely moving the left side.
• The right side oil reservoir fills about half-way when hot. The left side is markedly lower even though they both start out correctly. (just now thought of the fan direction. I'll check that)

After it's warmed up I can actually jam both levers all the way forward, and it won't jerk, but that's just a little too fast.

Any help would be greatly appreciated.

 

[cpurvis]

Have you tried bleeding the suspect hydro?

 

[MikePA]

No, but that's probably a good idea.

 

[MikePA]

Wasn't air in the transaxle. Guess I'll have to figure out how to replace the belt. Looks like it's going to be a pain.