Rebuilding one-way clutches

Rebuilding one-way clutches

When machining this converter...avoid careless material removal. The center ring was damaged by excessive material removal.

When machining this converter…avoid careless material removal. The center ring was damaged by excessive material removal.
When machining this converter...avoid careless material removal. The center ring was damaged by excessive material removal.

When machining this converter…avoid careless material removal. The center ring was damaged by excessive material removal.
The code stamped on the unit is visible for proper I.D.

The code stamped on the unit is visible for proper I.D.

Many to rque converter problems can be directly rela ted to improper sprag and roller clutch rebuilding. Many shops merely rotate the sprag to determine if it locks one way and unlocks the other. Professional rebuilders will entirely disassemble the stator assembly to clean, remachine if necessary, polish and replace rollers and springs. If you discover abnormal wear or find any cracks, you may want to discard the ent ire stator and rep lace with a l ike component.

While this sounds like a great deal of added effort, in reality, it is a necessity. This area becomes a trench full of waste debris, metal particles and grit. You may find broken springs, contamination and worn out rollers and races. In other words, this is a pool of disease infecting your newly rebuilt converter.

Another area of concern are the stator caps. Aluminum stator caps can become worn, plastic caps can be cracked and caps equipped with roller bearings may become worn out. Under careful examination, these slight imperfections may be noticed and corrected. Shudder, noise and vibrations can contribute to an improperly loaded roller clutch assembly. Performance or the lack of performance along with overheating may be directly contributed to a roller clutch not releasing or overriding properly.

Examine the stator itself very carefully. Metal transfer and worn out I.D. surfaces require attention. Remachining may be necessary to bring back to OEM specifications. One example is the TH440 or 4T 60E stator, which always exhibits burnishing and metal gouging on both stator and stator cap. Removal of the outer sprag race can be simple. Place the disassembled stator upside down inside your clutch bonder. Heat for five to ten minutes before removing the stator and tapping it on a table. The heat will expand the stator and the race will easily slide out. Removal of .002 to .004 material on the flat surface will remove any gouging that is present without affecting dimensional integrity. Clean the outer race and press it back into position. Inspect and replace any worn rollers at this time and replace all accordion springs. Reinstall the stator cap and the stator is now ready for installation.

After assembly, rotate the stator while holding the internal race and check for rotation. The stator should lock and unlock smoothly. Test this motion several times to ensure proper operation.

Note: If a spring retainer is used, be sure to check for straightness and integrity.

You may confidently deliver this converter for installation knowing that it has been carefully cleaned and reconditioned to like-new standards.

Not only does this process provide you with confidence, but also will assure your customer’s satisfaction by having a properly rebuilt converter.

Found in issue September 2005