Technical Bulletins

ROAD LOPE ON MFWD & 4WD TRACTORS

 

SYMPTOM: A loping, up-down, oscillating motion of the tractor occurring during road transport. Motion may become severe enough to cause rider discomfort.

NOTE: Do not confuse with tire flat spot.

PROBLEM: The radial runout of the tire, rim and centering of the tire and wheel assembly on the axle may be large enough to induce a loping motion of a mechanical front wheel drive tractor. This loping motion is generally induced by the front wheel assemblies.



SOLUTION:

  • Confirm that the tire beads are firmly seated on the rim bead seat. 
 
  • Increase inflation pressure in the front tires to following: 
30 psi for 2* or 8-ply rating 
36 psi for 3* or 10-ply rating Test drive the tractor for 5 minutes to work out any flatspots.
  • If loping still occurs, jack up the front axle and measure and mark the point of maximum radial runout (high spot) at the centerline of the tire. Rotate the high spot to the 10 o'clock position. Loosen the bolts fastening the wheel to the hub, allowing the assembly to drop down on the hub. Retighten the bolts. Test drive.
  • If loping still occurs, remeasure and mark the point of maximum radial runout (high spot) at the centerline of the tire. Rotate the high spot to the 12 o'clock position. Loosen the bolts fastening the wheel disc to the rim allowing the rim to settle down on the disc. Retighten the bolts. Test drive.
 
  • If loping still occurs, remeasure and mark the point of maximum radial runout (high spot) at the centerline of the tire. Also, measure and mark the point of minimum radial runout (low spot) of the rim bead seat. See illustration for location of the rim measure point. (INSERT IMAGE)
Match the tire high spot to rim low spot. Test drive.
  • If loping still occurs and if matching the high spot of runout of the tire to the low spot of runout on the wheel results in a total assembly runout over 0.125" the tire, wheel or hub may have to be replaced. If rear tire and wheel assemblies are at fault, similar procedures, mentioned above, must be utilized to get the total runout 0.30" or less.

 

Call Firestone Field Engineering at 1-800-847-3364 if there are any questions.