You may have heard the following terms thrown around when discussing Ring & Pinion Gear Sets: 2-Cut, 5-Cut, Face Hobbed and Face Milled Gears. We’ll explain the differences and how to identify them.

There are a few methods to produce Ring & Pinions and the 2 most popular are

  1. Face Milling or 5-Cut followed by Lapping
  2. Face Hobbing or 2-Cut followed by Lapping

You can also grind Face Milled gears instead of lapping, however, while growing in popularity this is not yet a common method used on OE or aftermarket gears. It is easy to identify a Face Milled versus a Face Hobbed gear by reviewing the Ring Gear tooth depth.

 

Heel https://www.cartechbooks.com/media/wysiwyg/21_9.jpgToe

Face Milled (5-Cut) Ring Gear: The Heel (Outside) of the Gear is taller than the Toe (Inside).

Heel https://www.cartechbooks.com/media/wysiwyg/22_9.jpg Toe

 

Face Hobbed (2-Cut) Ring Gear: The Ring Gear has constant depth from Heel to Toe. 2-Cut Gears also have a natural "bias" condition; that is, the pattern shows up slanted when the pattern is rolled with gear marking compound.

So how do gear manufacturers choose which method to use? 2-Cut or Face Hobbing is relatively new technology compared to the classic 5-Cut Face Milled method and requires large capital investments in modern gear cutting machines which offer increases in production speed. The jury is still out on which method produces the best gear as both have their advantages.

Most Aftermarket Suppliers only offer Face Milled Gears. Revolution Gear & Axle offers a variety of both, the majority of our gears offered are Face-Milled 5-Cut, but we also offer 2-Cut Gears on our Chrysler 9.25” and GM 8.5” ratios.