I hear the 400 horsepower level thrown around alot... since all the differential sees is rwhp... i'm assuming that means rear wheel horsepower. So would the statement a 9 inch 28 spline rear can take 400 rwhp be correct?
How strong are 28 spline 9 inch rears?
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302 coupe
Founding Member
it should be okay, if you plan to drag race alot with slicks you may eventually have some problems. Torque and inertia/shock load have more to do with it than horsepower. I'd run it.
BTW, the diff. sees somewhere between flywheel hp and rear wheel hp. The ring and pinion see the exact same load as the output shaft of the tranny.
BTW, the diff. sees somewhere between flywheel hp and rear wheel hp. The ring and pinion see the exact same load as the output shaft of the tranny.
302 coupe
Founding Member
don't get scientific on me, you will go down in flames 
Actually, at steady speed, the losses will be practically negligible. If you are accelerating/deccelerating the amount of energy loss will increase proportionally per change in rotational velocity of said driveshaft/u-joint/diff bearing. Anyway, it doesn't really matter. The fact remains that te diff will see a load that is between flywheel and rear wheel horsepower.
Actually, at steady speed, the losses will be practically negligible. If you are accelerating/deccelerating the amount of energy loss will increase proportionally per change in rotational velocity of said driveshaft/u-joint/diff bearing. Anyway, it doesn't really matter. The fact remains that te diff will see a load that is between flywheel and rear wheel horsepower.
Part of that equation is your traction. You can have 800 HP and without the ability to stick your launches the 28s will last. If you're jerking your nose up 4-5 feet even with ~400HP then you're gonna want to look into some 31s.302 coupe said:
There's a formula somewhere (Moser's website maybe) where you can calculate how much shock the splines can take. If I recall the 28s can take over 2500 foot pounds, but don't take my word for it
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