Part 7: Bringing the 8 1/4 Up to Speed

(above & right) The pinion went in first by lubing up the pinion bearing with oil, aswell as the splines. We started the splines on the yoke by lightlytapping it with a hammer. Then we greased the pinion nut. The pinion nuthas to crush the crush sleeve. This must be done very carefully. If yougo too far, you can't go back. The pinion ultimately should requirebetween 15- and 20-inch-pounds to turn. Guys like Eddie can spin it byhand and tell if it's tight or just right.

(above & next three photos) We oiled the carrier bearings, stuck in the adjusters, and bolted in themain caps. We installed the main caps carefully as sometimes theadjusters are crooked, and we didn't want to damage them.

Our Auburn carrier hit the housing requiring some grinding. So wecovered the pinion with a wet rag to catch the particles of metal. Justa little clearancing was required.

A yellow pattern maker was used to check how the gears mesh.

A dial indicator is used for checking the back-lash (the distancebetween the pinion and the ring gear). In this instance, it was too muchat .014-inch. We reduced the back-lash and rechecked the pattern onceagain. Still no good as the gears should mesh more to the center. Thecarrier needed to be removed to change the pinion depth with shims. Theoriginal shim checked out at .027-inch, so we went with one thatdisplaces .024-inch. That did the trick.

After the diff was buttoned back up, we filled the carrier with RoyalPurple gear lube. Synthetic gear oil has a greater resistance to heatand better lubricating qualities than its dinosaur-based cousin. Justwhat the doctor ordered for our sustained high-speed race last May.