How did that happen?
One of the keys to being successful in any repair is to do a thorough root-cause failure analysis on every unit you work on. Many seemingly unexplainable failures occur due to problems that are outside of the area you are looking at. By now every tech should know that components outside of the unit can create a failure. Failures recurring inside the unit mean that the part or parts that failed were influenced by other parts that were missed during the teardown and inspection of the unit. These are expensive mistakes as a problem that comes back under warranty is on the shop and undermines your customer’s faith in the organization. The examples we will look at in this article will highlight the importance of a careful total vehicle inspection before providing the customer an estimate. Once the customer hears what they believe to be the final number, that number becomes carved in stone, and it’s almost impossible to overcome if there are additional parts or labor required.
Wear in Magnesium Transfer-Case Housings
One OEM supplier estimates that 2 million transfer-case housings have been made from magnesium1. In the aftermarket, these parts have been working their way into transmission shops at an ever-increasing rate. The questions I discuss here are why magnesium transfer-case housings wear so dramatically while their similar aluminum counterparts do not, and how this affects repair choices.
The Great Unknown
Replacing parts is the last step in the repair process. The first step should be a methodical diagnosis to isolate the cause of the malfunction. This is not possible unless you understand how the component you are working on is supposed to operate and how it is related to the other systems that make up the modern motor vehicle.
Where the Rubber Meets the Road
About 75% of the technical calls we handle are dealing with transfer-case problems, usually occurring after a transfer case has been disassembled and repaired, or another reman or new unit installed. The conversations range from, “I took the transfer case apart and can’t find anything wrong with it” to “This is the third transfer case we put in the vehicle and I still have the problem,” or “The reman transfer case I just bought from you is doing the same thing.”