Ring gear and pinion tooth pattern interpretation
I know that my rearend is a 10 bolt and 3:73.1 but what size is it? I need to get a new ring and pinion set for it. The pinion has a tooth broke and one of the bearing was messed up bad! The truck has 190000 mile and this will be the 2nd time to rebuild the rearend. Last time they just put in a new locker and reused the gears. Guess that wasn't so smart! (thanks GM) Thanks!
P.S. 2001 GMC 1500 ext cab, short bed, 4.8L, auto, 2 pice drive shaft, 2wd,
GM10-373, OE Number 1259441, Ratio 3.73, Teeth 41-11.
You could have reused the gears, the rear end needed to be rechecked and adjusted. When installing the new rear end and it's not rechecked and adjusted, your new rear end will have the same faith as your old one had.
When setting the pinion position, many of the service manuals required a final pinion position check by using gauges that verified the dimension from the center line of the differential carrier (center line of ring gear) to the face of the pinion (button). This surface (button) is not used on all new gears for verifying the pinion position. The service tools will be used to establish the proper amount of shims required prior to installing the pinion gear. The final pinion position will be verified by using the GEAR CONTACT PATTERN METHOD.
The TOE of the gear tooth is the portion of the tooth surface at the end towards the center. The HEEL of the gear tooth is the portion of the tooth surface at the outer end. The TOP LAND of a gear tooth is the surface of the top of the tooth. Every gear has a characteristic pattern. When making pinion position changes, shims should be changed in the range of .002 inch (.05 mm) to .004 inch (.10 mm) until correct pattern has been obtained.
When a change is backlash is required, backlash shims should be changed in the range of 1 1/2 times the amount of backlash required to bring the gears into specification. For example, if the backlash needed to be changed by .004 inch (.10 mm), the shim pack should be changed by .006 inch (.15mm) as a starting point. The actual amount of backlash change obtained will vary depending upon the ratio and gear size.
High backlash is corrected by moving the ring gear closer to the pinion. Low backlash is corrected by moving the ring gear away from the pinion. These corrections are made by switching shims from one side of the differential case to the other.
When making changes, note that two variables are involved. Example: If you have the backlash set correctly to specifications and you change the pinion position shim, you may have to readjust the backlash to the correct specification before checking the pattern.
(1) Paint ring gear teeth with a marking compound to both the drive and coast side.
(2) Rotate ring gear one complete revolution in both directions while load is being applied with a large screwdriver or simular tool between the carrier casting and differential case flange.
Normal or desirable pattern. The drive pattern should be centered on the tooth. The coast pattern should be centered on the tooth, but may be slightly toward the toe. There should be some clearance between the pattern and the top of the tooth.
PATTERN MOVEMENTS
(1) Decreasing backlash moves the ring gear closer to the pinion.
- Drive pattern (convex side of gear) moves slightly lower and toward the toe.
- Coast pattern (concave side of gear) moves lower and toward the toe.
(2) Increasing backlash moves the ring gear away from the pinion.
- Drive pattern moves slightly higher and toward the heel.
- Coast pattern moves higher and towards the heel.
(3) Thicker pinion position shim with the backlash constant moves the pinion closer to the ring gear.
- Drive pattern moves deeper on the tooth (flank contact) and slightly toward the toe.
- Coast pattern moves deeper on the tooth and toward the heel.
(4) Thinner pinion position shim with the backlash constant moves the pinion further from the ring gear.
- Drive pattern moves toward the top of the tooth (face contact) and toward the heel.
- Coast pattern moves toward the top of the tooth and slightly toward the toe.
Ring and Pinion Installation Instructions
1. Remove the old gear set and thoroughly clean both the ring gear carrier and rear end housing with solvent. After cleaning, air dry all parts.
2. Always verify that you have the correct gear ratio that you have purchased. This can be checked by dividing ring gear tooth count by the pinion tooth count. e.g. (Ring gear tooth count 41 T, pinion gear Tooth count 11 T, 41divided by 11 = 3.73:1.
3. Many differential cases have many thousands of miles of service. Check all threads in the case for ware. It may be necessary to chase the treads to clean and align threads.
4. Check side bearing adjusters as they are often warped and out of shape making ring and pinion settings difficult. Replace as necessary.
5. Check ring gear back face for flatness. Generally after heat treating there may be a degree of taper. This may be rectified by lapping gear on sand paper on a glass flat plate. This will give you more even and uniform pattern when setting up you new gear set.
6. Careful attention should be give to blueprinting your rear end. Accurate clearancing will lead to a longer life for your unit.
7. All new parts should be thoroughly cleaned before assembly and checked for damage.
8. Examine the ring gear mounting surface for nicks or burrs which might prevent a flush mounting of the newly installed ring gear. Ring/Pinion tooth depth variations can result from a ring gear that is "cocked" on its mounting surface. If a ring gear spacer is to be used, also check it for surface imperfections. Nicks or burrs can be removed by using block-backed grit paper ora small file. Following material removal rewash in solvent and air dry. Mounting ring gear. Loctite ring gear bolts and torque to factory specifications.
9. All ring gear and pinions have been "Lapped" in sets and should never be mixed with another ring gear or pinion. Check to see serial numbers are the same on the ring gear and pinion.
10. Each gear ring gear and pinion is prerun and marked on the pinion face with its proper depth setting called the "Checking Distance". This dimension is from the face of the pinion to the axle center-line. A setting tool must be used to measure the checking distance. Pinion depth is adjustable by adding or subtracting shim thickness. Stay +/-.002 of the pinion dimension.
11. Once pinion depth is achieved using a new crush collar or preload shim pack set pinion bearing preload to 15 inch-pounds rotating torque with used bearings, and 25 inch pounds with new bearings. Once preload is set install the seal and loctite pinion nut.
12. Once the pinion gear is installed, position ring gear and carrier into housing to check backlash. Motive Gear and Motive Gear Performance ring gear and pinions are developed to be run at .008" to .012" back-lash for street gear sets.
13. Adjustments for backlash is done by spanner rings in the housing or shim packs behind the carrier bearing cups (GM) or cones (Dana). Always be sure carrier bearings are preloaded. The carrier should not fall out of the housing, but should have to be "tapped" in during final installation. Replace bearing caps and torque to factory specifications.
14. You are now ready to verify the tooth contact pattern. A gear marking compound should be used. Paint gear teeth with compound in several spots and rotate ring gear several revolutions. A tooth contact pattern will appear and should be similar to the pattern shown in. If the pattern is not in the approximate position shown, reset pinion depth and backlash to correct pattern. Pinion shims usually must be moved in .003 of an inch increments to notice a pattern change. If a pattern is heavy toe subtract shims, If a pattern is heavy heel add shims.
NOTE: Reverse the procedure for 8" and 9" Ford
15. Fill the case with required amount of GL6 Torco 85W-140W with additive gear lube, and maintain the proper level at all times. Proper maintenance is a must to protect your safety and the working life of you gear set.
Torque Specifications
Ring Gear Bolts
3/8" x 7/8" RH 55-60 FT#
3/8" x 3/4" RH 45-50 FT#
3/8" ALL LH 45-50 FT#
7/16" ALL 60-65 FT#
1/2" ALL 100-110 FT#
Carrier Cap Bolts
7/16" (5/8" head) 60-65 FT #
1/2" (3/4" head) 80-85 FT #
