GM 8.5" and GM 8.6" (8.625")Axle Parts, Gears, and Upgrades
GM 10-Bolt Axle Models:
GM 8.5"
1998 and Older
GM 8.6"
1999 to 2008
GM 8.6"
2009 +
Axle Specifications:
Ring Gear Diameter:
8.500 / 8.625
Diff Cover Bolts:
10 / 12
Ring Gear Bolts:
10
Axle Spline Count:
30 / 28 / 32
Axle Shaft Style:
Semi-Floating
C-Clips:
Yes
Crush Sleeve
Yes
Pinion Nut:
1-1/4" / 32mm
Pinion Support:
No
Carrier Breaks:
2.56 / 2.73
Dropout Carrier:
No
Torque Specifications:
Pinion Preload New:
14 to 19 in-lbs
Pinion Preload Reused:
6 to 8 in-lbs
Ring Gear Backlash:
.006" to .010" (5*)
.003" to .006" (2*)
Ring Gear Bolt Torque:
65 ft-lbs
Carrier Bearing Caps:
60 ft-lbs
Popular Applications:
Chevy Blazer / S10
1977 - 1998
F / R
Chevy Suburban
1977 - 2008
F / R
Chevy Silverado
1999 +
Rear
Chevy Tahoe
1999 +
Rear
Chevy Avalanche
2002 +
Rear
Chevy C10 / C25
1979 +
Rear
Chevy Camaro
2010 +
Rear
Cadillac Escalade
1999 +
Rear
GMC K5 / K25
1977 - 1999
F / R
GMC Yukon
1999 +
Rear
Hummer H3
2005 - 2010
Rear
GMC Sierra
1999 +
Rear
GMC Envoy
2002 - 2009
Rear
Axle Variations:
GM 8.5" 10 Bolt
1998 and Older with Drum Brakes
Small Carrier Bearings
Front and Rear Applications
28 / 30 / 31 Spline Axle Shafts.
Some older GM 8.5" front axles have a slightly different differential cover design with one bolt offset. Standard differential covers will still fit these axles when that one bolt is not used (or re-drilled).
GM 8.6" 10 Bolt
1999 and Newer with Disc Brakes
Large Carrier Bearings
Rear Solid and IRS Applications
30 / 32 (IRS) Spline Axle Shafts
GM 8.6" differentials can be installed in a GM 8.5" axle with the proper conversion bearings. GM 8.6" gears will fit GM 8.5" axles and as such have become the universal aftermarket size for both.
Axle Images:
Axle Details
The GM 8.5" 10 Bolt axle, also known as the GM 8.6" axle or GM 10-Bolt, is available in many front and rear axle applications including both solid axle and IFS / IRS configurations. While the GM 8.5" axle features an 8.5" diameter ring gear and the GM 8.6" axle uses a slightly larger 8.625" diameter ring gear, almost everything within the axles is completely interchangeable.
*Older "5-Cut" face milled gears have different set up specifications than the newer "2-Cut" face hobbed gears.
Note: This axle has a Carrier Break and gear changes may require a different carrier or thick gears.
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