December 31, 2009

RE5R05A Facts and Observations

Jeff Parlee

This transmission has been on the street since 2002 when it was first used in the Infiniti Q45 with the 4.5L engine. Since then, Infiniti and Nissan have used this transmission in many models. Currently, there are three versions of the RE5R05A valvebody.

  • The first design has two neutral to reverse accumulators on the lower body, behind the manual valve, and an empty valve bore under the low coast solenoid.
  • The second design has the same two neutral to reverse accumulators, but there is a reverse brake pressure control valve where the empty bore was.
  • The third design has one large neutral to reverse accumulator. These valvebody designs should not be interchanged.

In addition to the three design levels, Infiniti used a low resistance (10-15 Ohms) Low Coast Solenoid until August 2005. After August 2005, Infiniti used the same high resistance solenoid (20-40 Ohms) that has always been used by Nissan. To complicate matters, Bosch, Nachi, and Mitsubishi have all manufactured Low Coast Solenoids for this transmission. Solenoids of different manufacture can be interchanged, as long as their resistance matches.

Not all RE5R05A valvebodies have a Cooler Bypass Valve. I have seen the Cooler Bypass Valve bore empty on all three versions of this valvebody. When the bore is empty, the separator plate will be closed off above the Cooler Bypass Valve bore. See Figures 3 & 4.

Beware of the cooler! About one half of the cores we receive have water intrusion from failed coolers in the radiator. If the cooler has not failed on the unit you are working on, it is a good idea to replace it. It is only a matter of time before one will fail and damage your fresh transmission.

Jeff Parlee is Director of Product Support at Valve Body Xpress and a member of the Sonnax TASC Force® (Technical Automotive Specialties Committee), a group of recognized industry technical specialists, transmission rebuilders and Sonnax Industries Inc. technicians.

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