Here is the text from DTAC #79102, Sorry for the delay. Sounds like the longer bushing is the way to go. Be careful not to over-torque the bolt on the impellar shaft.
Complaint or Symptom :
Power flow impeller shaft bearings seized.
Problem or Situation :
Bearing failure or seizure may cause the belt to lock up & burn, impeller shaft to wear/score from turning inside the bearings, pulley that is bolted to impeller shaft to mushroom up on impeller side, or even allow the impeller to distort & damage the power flow housing.
Tolerance stack-up on the high end of the hub welded to the metal plate (AM130969BLE) where the bearings are seated, plus if the bushing (28H1885) that sits between the bearings (JD7142) is on the low side of its spec, will allow the bushing to be too short & not support the center of the bearings. Tightening the impeller & pulley (AM121832) creates a side load on the bearings & may cause them to bind and fail.
Solution :
Replace both bearings (JD7142) & install a longer bushing (28H1659) between them.
Replace any other parts that may have failed.
Check alignment of fan to make sure it is turning freely.
PARTS:
JD7142 Ball Bearing (2 needed)
28H1659 Bushing
Additional Information :
Bushing 28H1659 has an overall length of 0.562-in.
Bearings may also fail prematurely if water gets inside the bearing.
During re-assembly, there should be a gap between the end of the M144683 impeller shaft and the pulley. It is designed that way. Torque cap screw to proper torque and use loctite.
A print/drawing change was made in November, 2007 to tighten up the possible tolerances on the hub (welded to the metal plate). The tolerance inside the hub where the bushing sits was +/- 0.5-in, it is now only 0.13-in. It will be effective with the parts being made in December, 2007. It will go into weldments shortly after as the current inventory of hubs is depleted.
The 48HP, 54HP, & 62HP power flows were used on the LX, GT, GX, 400's, 500's Lawn & Garden Tractors, the X3/X5/X7 Select Series Tractors, & the Z425/Z445 EZtraks.
This bushing change was also made to the 48QT & 54QT power flows.