Document 94663

5/4/2C- Reading and Adjusting the
Ring & Pinion Tooth Pattern
1) Tooth Nomenclature. Terms for describing specific areas
of the gear teeth .
The gear pattern is the final check of a
p roper ins talla tion. It takes a bit of an "eye" to
rea d them p ro perl y, but w ith just a little practi ce
and coaching, everyone can learn to d o it.
(Outo:r rnd)
Face ( 1...... I..a.KI)
End view 01 tooLh rrom H ~I
(Out er encf)
Rank (Kuul)
Randy Sez
Reading Gear Patterns on New Gears
The only part of the pattern that helps me set pinion depth correctly is the co ntact position
between the face and flank . If the pattern appears to be toward the heel or toe, I pay li ttle or
no attention . W hil e making ad justme nts, the patte rn may also c hange toward the hee l or toe,
but in most cases this aspect of the pattern ca nn ot be put into a n ideal posit io n . Even if it doesn't seem intuitive or reasonable, I am onl y concerned with the pattern position between the
face a nd flank. I have fou nd that housing alignme nt a nd the exact pos itio n of the p ini o n bore
du ring manufacture affects the heel to toe pattern and ca nnot be altered without machi ne
work . Botto m li ne: a contact pattern tha t is centered from face to fl a nk a lways ind icates a correct pinion depth, eve n if a centered hee l-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 attention to the pattern on
the coast side of the ring gear when set ling up used gea rsets. This area provides the best indicator becau se it is
usua ll y wo rn less. Th e reverse wi ll be
true on standa rd cut ring gears used on
front ax les, so use the drive side for
read in g the pattern.
3) Rotate the ring gear in both directions over the
gear while doing it. This w ill help give you a nice
read on rear axles, but if a standard CuI ring gear
drive side. This is an acceptab le pattern, bu t look
painted areas using the pinion yoke to spin it. Supply some drag on the ring
clear pattern like this one. The pattern on the drive side is most important to
is used up front read the coast side. On reverse cu t gears up front, read the
at the followin g figures for more info on reading pa!!erns.
Acceptable Patterns
.-- ~--."
tl ~
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
I I ~I
5) These patterns show a pinion thai is too close to the carrier. In this case you wou ld remove shim thickness. How much thick\0 remove is a guesstimate, but it's generally recommended to do it in .OOS-inch increments.
Pinion is Too Far Away
II ~~ I
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 .