June 2006 Archives - Transmission Digest
Missing You

Have you ever built a unit that went out running absolutely fantastic but came back with a problem only a month or two later? Maybe you were so good to that transmission that it was missing you and wanted to come back for a visit!

4R100: Repeated Converter Failure

In this lesson we will hear of a 4R100 in a 2000 7.3-liter diesel with repeated (four times) converter failures.


Toyota vehicles using either the U140 or 240 series transmissions (see Figure 1) are known to produce a brutal 2-3 shift, to the point that the direct clutch disintegrates and spreads debris into the system, taking out the drum and cover (see Figure 2).

What Went Wrong and Why: Root-Cause Failure Analysis

Comebacks will have many causes, including some that are beyond the shop’s control – such as human error and new parts that are defective right out of the box. If a shop is not running at a comeback rate of 5% or less, it will be dangerously close to failing as a business. This is because there are two costs involved in repairing a comeback: The first is the parts and labor invested for free in honoring your warranty; the second loss is called “lost-opportunity costs,” which reflect the fact that when working on a comeback you cannot be working on a paying job. We will examine here how to make a comeback into a positive experience even though it costs money, and how to cut your losses and protect yourself from further wasted labor and parts dollars.

Getting Your Cores Back

When torque converters first transitioned from the early bolt-together units to the welded/sealed units of the present day, transmission shops were faced with a new challenge. Most customers weren’t willing to pay for a new OEM converter on top of the cost of a transmission overhaul. The only alternative available at that time – reusing the customer’s original converter – seldom saved the customer or the transmission shop any money. More often than not, reusing the original converter created new problems when contamination from the original failure entered the newly overhauled transmission.

June 2006 Issue

In This Issue
Shift Groups: Principles of Operation
Assembly Difficulties: K3 Hub and Rear Sun Gear

Hiring a Good Service Writer or Shop Manager

Many owners believe that they can save a $50,000-a-year salary if they do the selling themselves, but if they aren’t any good at it or their hearts aren’t in it they might be throwing away $150,000 in additional profits to try to save $50,000. I can understand the concept of running lean and mean if the phones aren’t ringing much, in which case a lot more promotional work needs to be done, but if they are ringing and the work isn’t being sold because of an owner whose sales techniques are questionable at best, not having a manager is a major mistake in judgment.