Ring & Pinion Gears

8620 Standard Gears

9310 "Pro" Gears

Large Pinion "Pro" Gears

Standard Gears are primarily used in oval track and street applications.  The material and heat treating provide excellent wear service life, but doesn't handle shock loads as well as Pro Gears.  9" Ford Standard Gears have a 28 spline pinion. "Pro" gears are designed specifically for drag racing.  The 9310 alloy and heat treat are ideally suited to absorb high impact shock loads.  9" Ford ratios from 4:86 to 6:50 have 28 spline pinions.  Select ratios available for 12-Bolt & Dana 60™. These 9" & 9-1/2" Ford gears are built specifically for ultra high horsepower drag racing applications from 9310 material.  All avaible ratios (3.40 to 4.86) have a large 35 spline shaft.

9" Ford Gear Notes

While many new 9" gears are now manufactured for clearance, many 9" Ford ring gears require modification to clear the pinion pilot bearing area.  Do not grind on the case.  Instead, chamfer the ring gear for clearance. 

Oval Track applications require a baffle to prevent all the lube from becoming built up in the right axle housing tube.  We recommend using one gallon of Torco GL-6 racing gear oil, SAE 85 w140  (part number 55-0030, 1qt.). 

If using a stock Ford front pinion bearing support, it must be the unit that has the HM89443 rear cone.  All Standard pinion pro gears must use a HM89444 rear cone.  This bearing has a larger radius that matches the increased radius in the pinion.  The recommended pinion support is our Heavy Duty Support, part number 57620 or 57670, which uses even larger bearings.  All 35 spline pro gears must use the pinion support, part number 57630 or 57680, with matching coupler or yoke. 

Some gears do not have the engraved pinion setting depth (OEM gears); however, the setting depth can be calculated.  The master housing dimension for 9" Ford is 4.375".  This is the distance from the centerline of the thirdmember case main bearing bores, to the shoulder that the stock rear pinion bearing would stop against.  By measuring the pinion head thickness, then substracting this measurement from 4.375" (master housing dimension), the setting depth is obtained.  Some of these pinions are marked with a + or - and a number.  This is the variance from the master housing dimension that the pinion needs to be set.  Example: If the pinion is marked +2, the master housing dimension would be 4.375" plus .002 or 4.377".


GM 12 Bolt Carrier Notes


Which Series Carrier?




2 Series

.590" NA

3 Series

1.020" .895"

4 Series

1.325" 1.145"

Check the distance from the bearing shoulder to ring gear flange ("A") to determine the carrier series for proper ring & pinion selection.


© 2018, Mark Williams Enterprises Inc.

Mobile Site

"Mark Williams Enterprises, Inc." uses cookies to improve its website. For more details and how to manage cookies, please see our privacy policy.

I accept cookies from this site.