Gravely Promaster 100 won't stay in a straight line!!

Discussion in 'Mechanic and Repair' started by Korey, Jul 5, 2007.

  1. Korey

    Korey LawnSite Senior Member
    Messages: 269

    I made the adjustments per the repair manual (jack mower up, loosen lever bolts, etc) and monitored tire pressure, but I have to keep correcting the levers while in motion to keep it from veering off and when I do that, it messes up the stripes. I know ZTRs are not that good on grades but it's horrible on even the slightest grade and it's really getting on my nerves!! Would like to be able to go in a straight line with the two levers in the same position but the mower will slightly turn wherever the lower part of the grade is as if the one wheel is almost in neutral. Is there any way I can fix this? Thanks.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    That's the nature of ZTRs, The rear is pushing the lighter front end around on caster wheels. The casters up front is why they won't track on grades.

    Have you checked and made sure the hydro belt is in good shape and not slipping ?

    If it tracks straight on flat ground there isn't much more I know can be done other than getting better at operating the joysticks (un-even) to form your straight line on grades.
  3. Korey

    Korey LawnSite Senior Member
    Messages: 269

    Thanks for the reply. I even have to correct the levers on flat ground. If it hits a small bump it'll start to veer off. Hills I understand, but even a very slight grade throws the whole thing off. I'll have to check the belts to see if they are tight. I know the pumps are perfectly good though.
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    It almost sounds like you have excess play in the joystick bushings or the control shafts (where you adjust tracking) or even the rod end joints. A little bit of play in all of these areas could cause one to steer loosely.
    Also check the activation arms on the hydro pumps for looseness.
  5. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Messages: 1,164

    This ^^^^^^ is the first place I would look
  6. Korey

    Korey LawnSite Senior Member
    Messages: 269

    Thanks a lot guys! I'm thinking it's definitely the activation arms on the pumps. Will let you know what happens.
  7. Korey

    Korey LawnSite Senior Member
    Messages: 269

    Wow, another thread that I did not reply to. This mower was a very old ZTR that I picked up for $1300 which got the job done until I upgraded. It was so old that it did not have those little shock absorbers by the controls which newer ZTR's have which cause the controls to move in a fluid like way meaning it is near impossible to do a jerking movements on the controls. Any small movement on the Promaster affected the controls, so any tiny bump would jerk the controls and cause me to constantly recorrect em. Eventually, I got so good at it that my lines were straight. When I upgraded the mower, I compared the differences between the two and realized the Promaster did not have those shock absorbers which kind of resemble car trunk struts.
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Thanx Loneman.....for following up...
    Ericg started a thread a few weeks ago about the unsolved threads in the archives of this forum..
    You would be surprised how many times the older threads are accessed for answers..
  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

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  10. herler

    herler LawnSite Fanatic
    Messages: 5,139

    Phhh I didn't know mowers were supposed to track straight, with mine it seems it's always some kind of angle on the controls and I got so used to it that's just something I hardly even notice, unless someone else points it out, doesn't phase me much at all.

    I do find it irritating when it smacks the side of the trailer thou, I can attest to that.

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