NEW TRANSFER CASE / REAR DIFFERENTIAL RING & PINION BREAK-IN PROCEDURE

The greatest damage to any new ring & pinion gearset usually occurs during the first thousand miles. During this time, the new gears are bedding-in which generates quite a bit of heat and if driven hard you will raise this temperature even further and may cause irreversible damage to the gears. This is because the surface finish of the new gears is not perfectly matched and hasn’t had enough run-time to allow the machine surface finish to wear itself to its final match. The ring & pinion gears are now lapped in at the factory and while this is a recent improvement they still must have sufficient run-time to allow the surface finish to properly develop. 

Over the course of several thousand miles the gears will bed-in, increasing the load bearing surface area while polishing themselves up nicely to where they are smooth and shiny.  This improved MSF (machine surface finish) reduces the heat that is generated and the larger load bearing contact area increases the overall durability of the gearset. It is wise to let the transfer case ring & pinion gears bed-in before pushing them to their material limits. This process takes about 5000 miles before the ring & pinion have fully bedded in.

Recommend procedure for breaking-in your new ring & pinion:

Follow the transfer case filling instructions provide on the FAQ section of this site. Vehicle speeds should stay below 60 mph for the first 100 miles. Drive the vehicle 20 miles, stop and let cool for 30 minutes.  Repeat this process at least 3 times. During the first few thousand miles the ring & pinion gears wear themselves in, Do not abuse or dump the clutch or do any hard acceleration, let the ring & pinion bed-in gently. If you take it easy on a new ring & pinion and perform regular oil changes it will last much longer.  Use caution when letting out the clutch as aggressive high rpm clutch dumps can fatigue parts and may lead to eventual failures.

Change the transfer case oil every 5000 miles. Vehicles that are being road raced require race car maintenance and all drivetrain oils should be inspected after each race and changed if the oil is dark or stinky. Road racing applications may add an additional 1/2 pint of oil to the transfer case for added lubrication and cooling. New or recently rebuilt transfer cases should have the oil changed after the initial first 500 and again after 1000 miles.

Transfer case oil recommendations