4R100 Flow Issues
The 4R100 has come by its flow problems honestly. It has inherited them from the E4OD.
Time to Change an Old Habit
Our industry is reporting an increasing number of converter leaks that are coming from this area. The normal stresses that are being exerted on the converter during acceleration – plus the extra stress of lockup apply – are causing the converter to flex. And the culprit is the sharp angle at the edge of the lockup surface (see Figure 1), which creates a flex point for a crack to start.
Indexing TCC-Piston/Damper Assemblies to Turbines
At a recent TASC™ Force meeting, one of the members expressed concern about an increase in the number of worn-out bores in TCC pistons that he was seeing. Although the problem is prevalent in many different pistons, his main focus was on the GM 298mm pistons.
Upgrading the Cummins Roller Clutch
When the Cummins diesel was offered in 1989 Dodge pickups, it could be purchased with either a manual transmission or a non-lockup 727 automatic transmission. The converter for the non-lockup 727 transmission was very similar to the 400 or AT540 converters and had many internal likenesses. The converter’s historic durability made it a good choice for this demanding application, but this converter also has some historic shortcomings.
Rebuilding the Unrebuildable?
Today’s torque-converter rebuilders face increasingly complex rebuilding jobs. Perhaps no other torque converter has put rebuilders to the test more than some of the ZF 5HP-style converters. These torque converters are manufactured with what is described as a “captive clutch” and would normally be considered a non-serviceable item.
Taking the Guesswork Out of Parting
Note: This article, the second in a two-part series on proper parting procedures, takes a look at a better method.
A Primer on Proper Parting Procedures
When the first automatic transmissions were introduced in the late 1930s, the fluid coupling was routinely serviced as part of a transmission overhaul. The fluid coupling was bolted together, and servicing it didn’t require any skills that a regular mechanic wouldn’t have. When the fluid coupling evolved into the torque converter, it was still a bolt-together unit, and the only new challenge for the mechanic was to learn about stators.
740/1740 Codes and Chrysler Converter Flow
740/1740 codes tell you there is excessive slip at the TCC clutch. The engine and transmission output speeds are constantly being monitored. You can compare the difference in the two speed rates to determine transmission slip. If the RPM parameters for a slip in a given gear are met and TCC apply has not been commanded, you will see a gear-ratio code. But, if the RPM parameters for a slip in a given gear are met and TCC apply has been commanded, you will see a (TCC slip) 740 code.
The GM 298mm Converter
You’ll hear some convincing arguments about how the selective (conical) plastic thrust spacer is used to adjust the stack height on the GM 298mm torque converter. You also will hear some convincing arguments about how this same selective thrust spacer is used to adjust the clutch-release clearance on the GM 298mm converter. The truth is that both statements are correct. The selective (conical) plastic thrust spacer may be used to adjust both the stack height and clutch-release clearance on this converter. What is important is to be aware that changing the adjustment of one also changes the other. As long as you know the proper parameters and parameter limits of both measurements, you can adjust both successfully.
