Gear Set Identification
The following information is marked on current drive pinion and gear sets, and will be used for identifying, matching and adjusting procedures.
- 1. The Part Number (1) is found on the shank or threaded end (4) of all pinions. On the ring gears, the numbers are normally found on the front face (2) of the gear. However, as an option, they may be located at the gear O.D. as shown.
For any given pinion and ring gear set, the ring gear will always have an even part number (i.e. 36786), and the matched pinion will have the odd part number (i.e. 36787).
NOTE: Always refer to the Part Number and Tooth Combination Number before starting the assembly. Check to be certain the pinion and gear match.
- 2. The Tooth Combination Number (3) is found on the shank or threaded end (4) of all pinions. On the ring gears, the numbers are normally found on the front face (2) of the gear. However, as an option, they may be located at the gear O.D. as shown.
The tooth combination number (i.e. 5-37) indicates the gear set has a 5 tooth pinion and a 37 tooth ring gear, the equivalent of a 7.4 to 1 gear ratio.
- 3. The same Matching Number (5), such as M29 or any combination of a letter and number, will be found on both the drive pinion and ring gear. All drive pinion and ring gears are manufactured and sold only in matched sets.
Most pinions have the number marked on the head end. However, on pinions with spline that are parallel-sided, the number (5) may be marked on the top flat of one of the splines.
The number on the ring gear is usually found on the front face (2) of the gear, although sometimes it may be on the gear O.D. as shown.
If either a pinion or a ring gear should ever require replacement, both must be replaced as a matched set. A ring gear and pinion which do not have the same matching numbers must not be run together.
- 4. Each pinion has a Pinion Cone (PC) Variation Number (6) which indicates variations (in thousandths of an inch) from the nominal mounting distance. This PC variation number is necessary because pinion and gear sets for a specific series of axles cannot be manufactured exactly alike, and there may be slight differences in the mounting distance of the individual gear sets. The PC variation number must be used to modify the nominal pinion gauge dimension when using a pinion setting gauge or when calculating pinion bearing cage shim pack thicknesses.
The pinion cone variation number (i.e. PC + 3 or PC - 5) is normally found on the spline end (4) of a pinion shaft or on the front face (2) of the ring gear. However, the number may sometimes be located on the ring gear O.D. as shown.
Dri-Loc Bolt Procedures
When new Dri-Loc bolts are used, identified by a visible patch of adhesive on threads, the locking feature is usable only once.
Procedure For New Dri-Loc Bolts:
1. Wipe excess oil and any residue from the threaded holes in the case. The holes should be relatively oil free, however, no special cleaning is required.
Do not apply a liquid adhesive or any other type of fastener retainer material, sealant or adhesive on new Dri-Loc bolts, or in the threaded holes.
2. Install and tighten the Dri-Loc case bolts to the specified torque value in Ground Drive Differential And Axle Fastener Torque Specifications chart for that size bolt. Dri-Loc will not alter the bolt torque requirement.
NOTE: No cure time is required for either the Dri-Loc bolts or for liquid adhesive prior to rebuilding the axle and returning it to service.
Procedure For Reuse of Dri-Loc Bolts or Regular Bolts Used With Liquid Adhesive:
1. Wipe excess oil residue from the bolts and threaded holes in the case, however no special cleaning is required. When reusing Dri-Loc bolts, it is not necessary to remove the Dri-Loc residue from the threads.
2. Apply liquid adhesive to only the threaded holes, letting four or five drops run down the side of each hole. Before installing the bolts, visually check to make sure that the liquid adhesive has contacted the threads.
Do not apply liquid adhesive to the threads of the bolt. The liquid adhesive will then be blown out as the bolt advances, since trapped air in the hole will create back pressure.
3. Install and tighten the bolts to the specified torque value in Ground Drive Differential And Axle Fastener Torque Specifications chart for that size bolt. Liquid adhesive will not alter the bolt torque requirement.
4. When servicing drive units assembled with Dri-Loc bolts or liquid adhesive in threaded case holes where the bolts do not require removal, check each bolt for tightness by applying the minimum amount of torque specified for that size fastener. If the bolt does not rotate, it is satisfactory.
If the bolt rotates to any degree, it must be removed from the case halves and liquid adhesive applied to the threaded hole. Use the procedures under topic Procedure For Reuse Of Dri-Loc Bolts or Regular Bolts Used With Liquid Adhesive.
Do not allow heat to exceed 177° C (350° F) maximum. Heating should be done slowly to avoid thermal stresses in the differential case and gears.
5. If bolt removal becomes difficult due to worn bolt heads or unusually high breakaway torques, apply heat to the bolt for only a few seconds at a time while trying to loosen it. Application of heat reduces the strength of both liquid adhesive and Dri-Loc below recommended installation torque.
Ground Drive Axle Torque Chart (Applicable Only For Axle Fasteners)