Orifice Control within the Converter, Part 2

Most torque converter rebuilders understand how oil flow within the converter harnesses engine torque and helps drive the vehicle. Unfortunately, many rebuilders have little knowledge of the many secondary paths and functions of converter oil flow.

Last month’s article, “Orifice Control within the Converter, Part 1” touched on two secondary oil paths. The first was the oil that bypasses the lockup clutch and the second was the balance oil that is allowed to pass through the turbine.

Rebuilders have many questions about some of the other secondary oil paths. Here are a few of the questions and their answers.

Why do stator caps and bearing adapters have passages for oil flow?

Figures 1a and 1b show two common oil passage configurations.

This is one of the least understood secondary oil paths in the converter. To better understand the effects of this oil flow, some primitive tests were set up. For test purposes, a baseline comparison was established by flowing oil through the passageways of stator caps with different passageway designs. The test used ATF at 80 psi, at a temperature of 180 F. The rate of oil flow through each cap was recorded, to be used later to compare performance. The caps were then installed into vehicles and road tests were conducted. At first, it appeared as if the oil passages had little or no effect on the performance of the vehicle. Then, one of the R & R men noticed that more than normal heat was coming off one of the converters that had been equipped with a stator cap previously recorded as having comparatively low flow. He could actually feel the heat radiating from the converter while the vehicle was still on his lift. When pyrometers were added to the cooler lines, the difference was very dramatic. The flow capacity of the oil passages in the caps had a direct effect on the working temperature of the converter.

To read the rest of this Technical Article on the Sonnax Website click here.

Article No.: TCTIP-09-09
Author: Ed Lee
Total Pages: 2

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