Besides being more efficient, the fully assembled unit is 8-9 pounds lighter than a comparable aluminum 9”assembly The 12-bolt pinion is closer to the the center of the ring gear, in comparison to a 9” gear, making the 12-bolt 3% more efficient than a 9” rear ( 9” pinion is 2.250” below the center of the ring gear compared to a 1.50” drop for12-bolt). We could easily use a 35-spline spool that would fit into a stock bore case however, our goal is to find the best solution for our customers the first time, which will save you time, money and grief in the long run. In addition, a vehicle that requires a 35-spline shaft is bound to break an OEM case (2.891”/3.0625” bore), leaving you to purchase another case while being stuck with a substantially weaker spool. When a 35-spline spool is designed to fit into a 3.0625” or 2.891” bore case, the bearing journal thickness is extremely thin- inevitably resulting in distortion or failure at the bearing journal.

When upgrading to a 35-spline shaft, in a 9”Ford, it is necessary to increase the case bore size to3.250” in order for the carrier (locker/spool) to have enough strength at the bearing journal. * Why do 35-spline shafts require a 3.250” bore case? * note spool wall is very thin on 35 spline Side Bearings ( differential )- (Timken Part #)

Mark Williams (with3.812' bearings), Strange (with stock large 3.063' bearings) and stock (2.892') Stock, N- nodular (stronger material) and WAR( 2 ribs but stock material) Aftermarket spools and cases are available that accommodate even larger bearings-3.250' and 3.812', The carrier with the 3.063' larger side bearings is the C7AW-G marked single ribbed case, it came from a late 60's GalaxiesĬase C4AW-4025-C may also be a large bearing single ribbed case. Some standard cases are also machined to take the larger 3.063”(the C7AW-G mainly) side bearings, most cases however (including N cases) will take the 2.892” side bearings. Aftermarket 45-degree pressure angle and OEM type splinesĪftermarket spools and cases 45-degree pressure angleģ3 spline and 40 spline gun drilled axles

9 inch ford rear axle bearings