5/4/2C- Reading and Adjusting the Ring & Pinion Tooth Pattern

The gear pattern is the final check of a proper ins talla tion. It takes a bit of an "eye" to read them p roperl y, but w ith just a little practice and coaching, everyone can learn to do it.

1) Tooth Nomenclature. Terms for describing specific areas of the gear teeth .

H~~I (Outo:r rnd) Co..'\St

Face ( 1 ...... I..a.KI)

End view 01 tooLh rrom H~I (Outer encf)

Coast

Rank (Kuul)

Drive

Drive (r.nnVl""ll)

Randy Sez

Reading Gear Patterns on New Gears The only part of the pattern that helps me set pinion depth correctly is the contact position between the face and f lank . If the pattern appears to be toward the heel or toe, I pay li ttle or no attention . W hile making adjustments, the patte rn may also change toward the heel or toe, but in most cases this aspect of the pattern ca nnot be put into an ideal posit io n . Even if it does­n't seem intuitive or reasonable, I am only concerned with the pattern position between the face and flank. I have fou nd that housing alignment and the exact pos it io n of the p inio n bore during manufacture affects the heel to toe pattern and cannot be altered without machine work. Bottom li ne: a contact pattern tha t is centered from face to fl ank a lways ind icates a cor­rect pinion depth, even if a centered heel-to-toe pattern cannot be obta ined.

2) The first step is to cover both sides of three or four teeth on opposite sides of the ring gear with marking compound.

Randy Sez

Reading PaUerns on Used Gears Pay the most attent ion to the pattern on the coast side of the ring gear when set ­ling up used gearsets. This area pro­vides the best indicator because it is usua lly worn less. The reverse wi ll be true on standa rd cut ring gears used on front ax les, so use the drive side for read ing the pattern.

3) Rotate the ring gear in both directions over the painted areas using the pinion yoke to spin it. Supply some drag on the ring gear while doing it. This w ill help give you a nice clear pattern like this one. The pattern on the drive side is most important to read on rear axles, but if a standard CuI ring gear is used up front read the coast side. On reverse cu t gears up front, read the drive side. This is an acceptab le pattern, bu t look at the following figures for more info on reading pa!!erns.

Acceptable Patterns

Hcd

II~I

.--~--."

I.)ri,,~

tl~

Tur. II ....... ·"

4) These are all acceptable patterns. You wan t to see pa!!erns that have soft edges to them. In general, pattern movements can be summarized this way:

1) Moving the pinion gear closer to the carrier will move the drive side pattern closer to the flank and sligh tly toward the toe. The coast pattern will move deeper toward the tooth flank and slightly toward the heel.

2) Moving the pinion away from the carrier will move the drive pa!!ern toward the face and slightly to the heel. The coast side will move toward the face and to the toe.

Pinion is Too Close

lIcd

I I~I II~I

5

5) These patterns show a pinion thai is too close to the carrier. In this case you wou ld remove shim thickness. How much thick­ness \0 remove is a guesstimate, but it's generally recommended to do it in .OOS-inch increments.

Pinion is Too Far Away

II~~ I Il t'lI'J Hocl

Hocl II~I

6

6) These show pattern s indicating the pinion is too far away from the carrier. In this case, you would add thickness in .005-inch increments until the correct pattern is obtained.