Are all GM 12 bolts the same?
A different 12-bolt differential was used for light truck applications, but those 12-bolt units are not directly interchangeable. You can identify a truck differential by the smaller, 1.438-inch diameter pinion shaft and the size of the rear cover, measuring 10.875 inches by 10.875 inches.
Are all GM 12 bolt rear ends the same?
They are not interchangeable. That doesn’t mean the truck rearend is not capable of receiving performance upgrades. To the contrary, aftermarket 30-spline differentials and axles are available. GM car and truck 12-bolt rearends are easily distinguishable by the cover shape.
What size ring gear is in a GM 12 bolt rear end?
8.875-inch
12-Bolts to Glory The GM 12-bolt debuted in 1965 and was mass-produced until 1972. It features an 8.875-inch ring-gear carrier held in place with two internal main caps. The pinion gearshaft measures 1.625 inches in diameter and is shimmed to achieve the proper pinion depth.
Are 10 bolt and 12 bolt axles the same?
12 bolt axles have 30 splines, 10 bolt have 28, but yet both axles are the same lenth and diameter. That means that if the 10 bolt had a 30 spline carrier the 12 bolt axles would bolt in.
How do I know if my 12 bolt is posi?
If you see springs in the window of the carrier, either coil springs like this or an S-shaped spring, it’s a Posi unit.
What gear ratio is a 12 bolt Chevy rear end?
Probably the easiest 12-bolt differentials to find are the type 2 units. These are found primarily in standard-performance Chevrolet passenger cars. Type 2 ratios were somewhere between 2.29:1 and 2.73:1.
How do you find the gear ratio on a 12 bolt?
The small number is the pinion gear tooth count; the large number is the ring gear tooth count. You divide the big number by the little number to get the ratio. Here, 40 ÷ 13 = 3.076, so these are 3.08:1 gears. This 3.73:1 ring gear fits the GM 12-bolt passenger car carrier.
How strong is a 12-bolt rear end?
Chances are your truck has a 12-bolt rearend, but if not, it’s fairly easy to get your hands on one. Not only are they common, but they can also be pretty solid when built correctly. In fact, they can stand up to around 800 hp, which is perfect for a street truck with some performance mods under the hood.
How do I know if my 12-bolt is posi?
How do you find the gear ratio on a 12-bolt?
Count the number of teeth on the pinion gear and count the number of teeth on the ring gear. Divide the ring gear teeth number by the number of teeth on the pinion. The result is your gear ratio.