On the left is the 13.4-pound...
On the left is the 13.4-pound carrier we are ditching in favor of the 5.6-pound five-bolt steel spool from Quick Performance. It's a win/win situation: We are getting a stronger piece and losing 7.8 pounds of rotating weight at the same time.
Final Check Unlike many gear specialists, Mellentine uses gear-check paint on both the drive and coast sides of the teeth all the way around the ring gear when checking lash. When doing a wear pattern test, you are looking for a consistent pattern all the way around the teeth and for the contact on the thrust face to be near the bottom of the teeth. When the gears are under torque, the contact patch will move up the face of the ring gear teeth. You want the pinion gears to make complete contact with the ring gear teeth and not walk off the top.
Also, instead of checking just a single point for lash, Mellentine marks four points on the ring gear and checks lash with a dial indicator in all four locations to make sure there are no warping or runout problems. Lash must be between 0.006- and 0.009-inch to fall between Mellentine's acceptable parameters. If lash is too tight, the rearend will suffer from excessive heat buildup and can scuff the gears. Too little and you run the risk of breaking pinion teeth. Finally, Mellentine resets the dial indicator to the back face of the ring gear and spins the pinion-again to check runout. For this check, he wants to see no more than 0.0025-inch variance. This check is not for the quality of installation but for the quality of the ring gear and spool. Too much variance means there is an alignment problem. There's no fix in this situation other than to determine which piece is at fault and replace it.
On the left is the 13.4-pound...
On the left is the 13.4-pound carrier we are ditching in favor of the 5.6-pound five-bolt steel spool from Quick Performance. It's a win/win situation: We are getting a stronger piece and losing 7.8 pounds of rotating weight at the same time.
For more longevity, Mellentine...
For more longevity, Mellentine recommended using a larger pinion bearing (left) and retainer in place of the smaller stock bearing.
Mellentine paints the ring...
Mellentine paints the ring gear all the way around to check the mesh pattern. Also, to get a more realistic pattern, he uses a belt to put resistance on the pinion and turns the spool.
Lash is checked at four locations...
Lash is checked at four locations on the ring gear, each approximately 90 degrees apart. All four must fall between 0.006 and 0.009 of an inch.
In high-horsepower race cars,...
In high-horsepower race cars, the standard crush sleeve (left) used for locating the pinion can continue to crush. This leads to damaging pinion slop. To eliminate this potential hazard, Mellentine uses steel sleeves (right).