Mark Williams Enterprises has developed a new 4.000" bore case for 9" Ford rear end applications that employs angular contact ball bearings and significantly reduces friction while improving service life. A companion angular contact dual ball bearing pinion support also reduces drag and can enable cars to run quicker thanks to improved driveline efficiency.
The new M-W case is clearanced to accommodate up to 10" ring gears and the big 4.000" angular contact ball bearings provide better race strength than with tapered roller bearings. Likewise, the dual ball bearing pinion support, with inner and outer bearing raceways angled to accommodate radial and axial loads, reduces friction and increases performance potential. Both are available with full ceramic ball bearings for even more efficiency.
Manufactured from an aircraft aluminum alloy that’s 30% stronger than commonly used 6061, the case is precision CNC machined to assure exact component alignment. Featuring the M-W developed Thru-Bolt™ design, the case is available with either steel or aluminum bearing caps. The pinion support can accommodate 28-tooth and 35-tooth pinion splines.
Complete thirdmembers featuring 100% ball bearing efficiency are available with gear ratios from 3.70 to 6.20:1. For additional information go to or call the factory at 800-525-1963 for personalized tech assistance. Founded in 1964, M-W is located in Louisville, Colorado.