10-Bolt Differential Upgrade

With some modern parts and a little TLC, the 8.2 10-bolt can be a great rear for the street.

Patrick Hill Jul 17, 2012 0 Comment(s)
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The 8.2 10-bolt rear first debuted in some '64 models alongside the older 8.4-inch third-member/dropout rear that had been around since the '50s. It owed some of its design to the 8.4, using the basic mounting dimensions of the 8.4's ring-and-pinion as the basis for the 8.2 design. The differential uses 3/8-inch mounting bolts for the ring gear, and has a 25-spline, 1.438-inch diameter pinion shaft. The stock axles were 28-spline, 1.20-inch diameter units. The early housings were cast from grey iron, while later housings were ductile iron.

The 8.2 was in production from '64 through the '70-71 model years (we've even seen the 8.2 pop up in a few '72s over the years as well). In 1970, the new, stronger 8.5-inch 10-bolt came out, and the 8.2 was put out to pasture once existing supplies were exhausted. For base model cars and moderate performance output, the 8.2 holds up fine. But when you start adding more horsepower, harder launches, burnouts, and all sorts of other performance abuse, the 8.2 can quickly eat itself. Usually it would be pitched in favor of the bigger 8.5 rear, or a 12-bolt if one was available.

Today the supply of used 12-bolts is dwindling fast, and even the 8.5s are starting to bring higher prices on the used market. Meanwhile, the old 8.2 languishes away, and supplies are plentiful. It was installed in Camaros, Novas, Chevelles, Caprices, Impalas, El Caminos, and Monte Carlos over its lifespan. Millions of them are still out there still, available for chicken feed when compared to the stronger units, and ready for rebuilding.

The aftermarket has parts available to boost the horsepower/torque capacity of the smaller 10-bolt, and with some upgrades these rears can withstand horsepower and abuse similar to the 8.5 10-bolt. To show off what you can do, we're gonna take the 8.2 from a '70 Malibu and make it a strong street and mild strip warrior.

Parts List

  • ETN-19603-010--Eaton differential, performance Posi, 28-spline 8.2 carrier
  • SAG-EV10-2C--Superior Axle & Gear 4340 chromoly direct fit 28-spline axles
  • CMB-14-0039--Summit Racing ring & pinion install kit (3.55 ratio)
  • SME-8510300--Summit Racing differential cover
  • BEN-33447--Wheel cylinders
  • SUM-B245--Brake shoe set
  • SUM-7104K--Summit Drum brake hardware kit
  • SUM-AD8208--Summit replacement aluminum brake drums

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