Up To Standards Archives - Page 5 of 10 - Transmission Digest
Diagnosis of Electronic ‘Active’ Transfer Cases

This is the fourth article in a series devoted to diagnosis of manual transmissions and transfer cases. Electronic “active” transfer cases cause 70% of the tech calls we receive.

Diagnosing Noises in Manual Transmissions

Continuing with our third article in the series on manual-transmission diagnosis, we now concentrate on noise. Noise is a difficult and time-consuming problem if you do not follow a prescribed step-by-step diagnostic process. Every rotating or moving part in a vehicle creates some noise. The vehicle itself moving through the air creates noise. Tires, exhaust, and suspension parts create noise as part of their normal operation.

Advanced Manual-Transmission Diagnostics

In last month’s article we started this series on manual-transmission diagnostics. We continue here with a more-advanced discussion. We covered the absolute need for all technicians to understand the theory of operations and power flow of the units they are working on so they can successfully diagnose problems. The topic addressed in this month’s article is shift problems, their causes and fixes. The next chapter will deal with diagnosing noises, and we will close the series with advanced electronic and function diagnosis of electronic and active transfer cases.

Manual-Transmission Theory: Back to Basics

On automatic transmissions, engine-related computer problems can affect transmission operation. Computer-controlled vehicles have very complex electronic circuits and multiple computers, all of which need to work together. That being the case, we will start with the basics of rear-wheel-drive manual-transmission function and proceed to more-complex diagnostic issues with transfer cases and front-wheel-drive manual transmissions in the next series of articles. Transmission designs may vary in size, shape and appearance, but all the units function in the same manner.

Understanding the Tremec 3650 5-Speed Transmission

The T5 was one of the most widely used transmissions in history. Ford replaced it for the Mustang with the T45, which was used in the Pony cars until 1991. Tremec then designed and got accepted by Ford the Tremec 3650, which replaced the T45 in Ford Mustangs in 1991 and is being used in 2007 production. Figure 1 shows other vehicles in which the 3650 is used.

Japanese Transmissions, American Cars

In the past, manufacturers of low-volume vehicles such as Rolls Royce and Jaguar used GM transmissions and A/C systems rather than design and develop their own. The trend has enlarged and continued so that the automakers looking to cut costs and increase efficiency are relying more on their tier-one suppliers to design and develop complete components such as transmissions and transfer cases. This has created a growth in units of a common design now showing up in many different vehicle platforms, from U.S.-built to imported brands.

Why Doesn’t It Shift Correctly?

The first step to any diagnostic solution is to understand the theory of operation of the components involved in the problem and how they relate to each other. What is involved in making a shift with a manual transmission? The clutch set and related components (hydraulics, pilot bearing, release bearing, motor and body mounts etc.) and the transmission internal components and shift mechanism.

Prime Cuts – New Technology for Ring and Pinion Gears

Every shop in this industry is working hard to increase the volume of its business and the percentage of profit. Repair and diagnosis of automatic and manual transmissions and transfer cases are generally deemed to be the core of the business. Clutch replacement, driveshaft work, CV joints and wheel bearings are common sale items, but many shops neglect differential work as a profit center.

Searching for Identity

Identification of the vehicle and unit you are working on is the beginning of doing the job correctly. It is getting increasingly difficult to obtain the correct information and even to locate a service manual or Internet site.

Repairing the New Venture 261 & 263 Transfer Cases

For the 1999 model year, GM introduced the new Chevrolet Silverado and GMC Sierra models of pickup trucks. As part of the upgrade of these models, New Venture Gear designed a new series of transfer cases, the NV 261 and 263. These transfer cases are basically a heavier-duty version of the NV 241 transfer cases used before 1999.

Theory, Facts and How What You Don’t Know Can Hurt You

To start this off with a bang, transmission repair is now an outdated term. Sure, you work on transmissions, but in reality you are working on a motor vehicle. This vehicle has an engine, a transmission, a driveline, a suspension, brake system, cooling system etc.

The New Year: It Will Be as Good as We Make It

The “Big Three” domestic automakers are facing the toughest business decisions since the Great Depression. Most of the Tier One OEM suppliers to the domestic market are either in bankruptcy reorganization or have downsized and sold off unprofitable divisions. The unions are in tough shape with plant closings and the movement of domestic manufacturing offshore creating a great loss of jobs. Our industry is intertwined with the automakers, and the times are difficult. It is easy to lose hope, it is easy to throw in the towel, and it is difficult to work out a solution to the present situation.