8.8 High Pinion

Many off-roaders are plagued with the problem of lifting their vehicle for more clearance only to find that they really didn't gain much in the way of driveline clearance and their driveline angles now create more problems than the gains in clearance were worth.

One way to achieve more driveline clearance and reduce universal joint angle is to use a special center section with reverse rotation ring & pinion gears. Both Ford and GM have used this design in the front of 4WD vehicles for years. A reverse rotation ring & pinion has the opposite tooth spiral on the gear teeth than a standard rear differential uses. If a standard rotation differential was flipped upside down, the results would be the wheels turning in reverse while in forward gears and in forward when the transmission is in reverse. The reverse spiral on the gear teeth make it possible to raise the pinion above the axle centerline and still drive the wheels in the right direction.

Many people have made a good living out of building expensive differential housings with reverse Dana Spicer center sections (originally produced for Ford applications) which solve the driveline angle and clearance problems by raising the centerline of the pinion shaft. Now there is a solution for those of us who do not want to use (or can't afford) the Dana Spicer solution. Other aftermarket suppliers have developed a high pinion, bolt-in, third member, that uses a reverse rotation ring & pinion and fits into a standard 9" Ford housing without any housing modifications necessary. These units can be used in either the rear or in the front with a custom front 9" housing.

A long overdue solution for an age-old problem of driveline angles is now available in a unit that is affordable and strong. This aftermarket 8.8" reverse third member uses off-the-shelf parts to build a unit that will stand up to abuse.

This high pinion drop-out housing is made from nodular steel, uses extra heavy duty steel caps. It is available with a cap size to fit ether 28 and 31 spline axles, or in an oversize version for 35 spline axles. One of the best features is that it uses any stock or aftermarket design 9" Ford differential carriers, including standard open diffs, limited slips, lockers, and Air Lockers. It also uses a readily available ring & pinion which came stock in 1998 & newer Ford IFS front ends. This reverse ring & pinion from the newer IFS is really the basis for the whole design. These ring & pinions are not only strong, they are available in many ratios from 3.07 to 4.56, and other ratios will probably be released in the future.

Another great feature of this design is the bearings used to support the pinion. The outer pinion bearing is much larger than the stock Ford design and it holds up well with large tires, even when used in the rear of an everyday driver. The oil ports in these housing are also superior to the Dana designs used in Fords. The Dana housing holds oil for the pinion bearings in a small reservoir cavity where there is not much oil flow. These aftermarket high pinion cases have a small return port ahead of the front pinion bearing that allows oil to flow through the bearing and back to the gear case. When used in the rear of a vehicle, this flow through oiling not only lubricates the bearing, it also dissipates heat created by the "pinion pull" that is unique to reverse rotation gears

The aftermarket high pinion has been designed as a rear-application unit and has the proper oiling required for long life. Reverse rotation front ends that are used at the back have less than desirable oiling due to their design.

These new aftermarket high pinion rearends finished first and second place out of fifty two vehicle in the BFG rock crawling championships held in Las Cruses New Mexico in November 1998. Both 28-31 spline and 35 spline units are now available from Randy's Ring & Pinion.


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