Posted by Maz on March 30, 04 at 06:48:42:
In Reply to: Request more info posted by Traveler on March 29, 04 at 19:00:33:
:so diff gurus please chime in.
I am not a guru on anything automotive; however, below is a write-up from the 4wheeler magazine on GM axles. Maybe it'll be of some help.
-Maz
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GM 10-bolt
Unfairly, this axle has been the redheaded stepchild in the family of GM axles. Why is this unfair? Because it boasts an inner pinion bearing that is stronger than the one found in a 12-bolt axle, and the pinion-shaft diameter is also larger. Before you run out and snag a 10-bolt, though, be aware that GM offers seven different variations of this axle.
Applications: Front and rear.
Type: Semi-floating.
Spline count: 28 and 30.
Factory ratios: 2.56:1 through 4.56:1.
Maximum tire size for stock axle: 35-inch.
Strong point: Strong ring-and-pinion for its size, large ring-gear bolts, spider gears and pinion diameter (when compared to its competition, the Dana 44).
Weak point: Avoid the centrifugal-force-triggered Gov-Lok locker.
Junkyard jewel: Find a 10-bolt-equipped Chevy Blazer or Suburban built after November 1989 through 1991 because it will have 30-spline axleshafts.
Building secrets: The axle-tubes can spin on the center-section, so notch the housing where the axle-tube meets the center-section and re-weld.
GM 12-bolt
This axle was manufactured in both 5- or 6-lug bolt patterns. If you trash the 12-bolt in your '73-to-early-'80 4x4 Chevy truck, you'll be happy to know that you can simply install your 6-lug axle-shafts into a two-wheel-drive 12-bolt axle and return to the trail.
Application: Rear.
Type: Semi-floating.
Spline count: 30 (after '68.)
Factory ratios: 2.50:1 through 4.56:1.
Maximum recommended tire size for stock axle: 35-inch.
Strong point: Larger-diameter ring gear than 10-bolt (8.875-inch).
Weak point: The pinion bearings are small and fail often.
Junkyard jewel: Some '76-or-older Chevy ½-ton trucks had a good Eaton coil-spring-type limited-slip.
Building secrets: Some ratios allow the use of a 12-bolt automobile gearset, which, interestingly, uses a larger-diameter pinion shaft.
GM 14-bolt (10½-inch ring gear)
The GM 14-bolt came in both a 9½-inch ring gear and a 10½-inch ring gear, and they're totally different animals. The latter is the more desirable, and its only resemblance to the 9½-inch is the number of cover bolts.
Application: Rear.
Type: Semi-floating.
Spline count: 30, 33.
Factory ratios: 3.23:1 through 5.14:1.
Maximum tire size for stock axle with 10½-inch ring gear: 44-inch.
Strong point: It features a removable pinion support and a pilot bearing at the end of the pinion shaft for added strength.
Weak point: The left-side carrier cap is known to break through the bolt hole.
Junkyard jewel: Find one on a '73-to-current ¾- or 1-ton Chevy truck. The newer the axle, the better.
Building secrets: Replace the Gov-Lok diff with an aftermarket unit.