87vette81big said:GM Corporate 8.5 good for up to 500-550 Flywheel Ft/lbs torque.
Momentarily .
Not no higher . My experience building & using them.
With the rear diff cover off, in the center of posi unit there will be an S shaped clutch pack preload spring also.
Diff case cross shaft pin runs through spring cutout.
Some Pontiac Grand Prix 8.5 had no clips. Bearing end axle shafts lke a 9", Dana 60, 9.300 Pontiac.
Be ball bearing or tapered roller bearing axle shaft bearings.
Knowing how much torque you are applying (this assumes you have perfect traction with only a 10% slippage at your slick) to the axel here is a chart of aftermarket axels listing their failure points (on average).
28 spline axel________1.200" dia. ________ 4,571 lbs.-ft. stock (GM test data)
28 spline axel stub ___1.250" dia. ________ 3,787 lbs.-ft. stock Corvette (Dana 44)
30 spline axel________1.250" dia. ________ 6,473 lbs.-ft. stock (GM test data)
31 spline axel________1.315" dia. ________ 7,000 lbs.-ft. (Ford 8.8" rear)
33 spline axel________1.370" dia. ________ 8,200 lbs.-ft. (GM 14 bolt truck)
35 spline axel________1.500" dia. _______ 9,600 lbs.-ft. (Dana 60)
40 spline axel________1.710" dia. _______ 12,000 lbs.-ft.
Here is a web site with a great graphic that shows why spline count is so important.
http://performanceunlimited.com/documen ... guide.html
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keep in mind a 500 ft lb of torque engine running thru a 3.73:1 rear gear is exerting over 1865 ft lbs of torque, impact loads easily triple that MINIMUM, if you insist on leaving a bit of slack in the drive train and having 3500rpm launches with slicks[/color]
the 10 bolt GM rear will hold up to abuse but the 12 bolt is larger and stronger, but Id point out that I,ve built several 496 and 468 big block performance engines that easily shredded 12 bolt G.M. rears, so if you do expect to race, a car,with slicks or race tires, a stronger 9" ford or even stronger still DANA 60 would not be a bad idea[/b]
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