Freudenberg-NOK New Development Spotlight: RE5R05A Sealing Rings

The RE5R05A automatic transmission was first introduced to the market in 2002 in the Infinity Q45. Several other vehicles used it in later years with some models such as the NV, continuing to use this transmission through the 2016 production year. Since its inception, the transmission designer, JATCO has used rigid sealing rings produced with PEEK material in several locations within the transmission assembly depending upon model and year. As well, JATCO designed the Subaru 5 speed also referred to as the TG5C. This unit is based on the RE5R05A with the exception that all of the Subaru 5 speeds are all-wheel drive units with the typical final drive unit incorporated into the transmission. 

The sealing rings used in the RE5R05A vary in design and material by model, as well as years within the model. This has led to confusion at repair facilities. Conversely, the rings used in the Subaru 5 speed, are consistent in style as originally designed. All sealing rings used in Subaru applications are made using PEEK material, and are designed with a scalloped inner diameter and a 3D joint.

Trust TransTec for your sealing needs - click here to learn more.

The Construction of RE5R05A Rings

All RE5R05A’s use a scalloped, 3D joint ring made of PEEK material on the input shaft, from the factory. TransTec® engineers have worked with rebuilders and Freudenberg-NOK Fluid Power engineers to redesign a Teflon® ring with a step joint that not only performs better in the vehicle but also bench checks better.

Speaking of bench checks, whether hydraulic or air check a higher leak rate should be expected when testing most OE designed plastic style rings. The rings are originally designed to fit loose in the bore to ease the assembly process during transmission production. This fit helps to eliminate ring breakage caused by the ring hanging out from the ring lands, then catching on the bore during assembly of the components. The loose fit design will work even though the ring doesn’t hug the bore because at cold start of the vehicle, the transmission fluid is thick. This ensures only minimal leakage past the rings.

To learn why not all sealing rings are created equal, see our recent blog post on the topic.

After the transmission heats up, fluid begins to thin but the ring expands in size due to thermal expansion. This thermal expansion provides positive sealing to the bore reducing the leak rate even further. Unfortunately, this design doesn’t provide much confidence for the builder when bench checking the unit. When the OE ring is not available in the aftermarket, TransTec® engineers redesign it with a free-state diameter slightly larger than the bore, ensuring the ring will hold to the bore to produce a better bench check and also perform properly when installed in the vehicle.

The three rings on the reverse brake (center) support provide fluid to the direct and hi-low/reverse clutch assemblies. These rings were originally manufactured in a few different designs. One design is the same as the input rings, made with the scalloped, 3D joint. The second design is a “T” design with a 3D joint. According to recent OEM parts film, the center support ring with scalloped design has changed to the “T” design with one exception. The Subaru 5 speed still uses the original scalloped design. TransTec® offers only the “T” design for both the RE5R05A and the Subaru 5 speed. The “T” design has been shown to have less leakage than the scalloped design, especially when the ring land area of the support is showing wear. Of course, this design can’t make up for a support that should be replaced due to excessive wear.