Quote:
Originally Posted by MechEngVT
The Ford 9" rear is one of the least efficient of the common mass-market rear axles. It is a semi-hypoid, where the pinion gear is further offset below the axle centerline than a pinion would be in a typical helical bevel gearset. Hypoid gears are at least 3% less efficient. The Ford 9" rear is popular among hot rodders because it is common (i.e. inexpensive and its ubiquity provides many gear ratios to choose from), it is a "quick-change" style rear (the ring/pinion/carrier is assembled to the pinion housing as a unit which drops into the axle housing), and the low pinion allows driveshafts to clear in low-slung street rods and lowriders. Efficiency has nothing to do with its popularity.
A GM 10 bolt or even a 12 bolt would let you recover that 3% efficiency loss from the gearset alone. It would be a pretty big deal when you're talking about gearsets that are about 94 vs. 97% efficient.
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thank you for the clarification on the 9" ford. miseducation @ work, many places i read more efficient, stronger, better...
now for the 4:10 "i was headed the other direction" what i need is a 3.31 or a 3.55. i need to lower engine rpm desperately. the truck is an 86' f-250 1/2 ton/single wheel, xt cab.
since you are recomending GM, will the axle fit? bolting up to the springs seems universal but how about shock mounts and brake connections.
also is the displacement from the master cylinder appropriate for the drums
of the GM axle? am i likely to find this axle at the wrecking yard?
if i find one with disk brakes would it be preferable?
finally, how many teeth would i be looking for on a 3.31?
ty!!