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TF999, slight whirring sound in park/neutral


Lifetime Member
Have a fresh rebuilt TF999 that has a faint “whirring” noise that is only present when in park and neutral. This noise only appears when I shift from one of the three forward gears (D, 2, 1) then into neutral or park. If I go from reverse into neutral/park the noise doesn’t show up.

While the transmission is making the noise in Neutral, if I shift the transfer case to neutral, the sound goes away. I can engage the transfer case back into gear and the noise comes back.

The transmission shifts great and has no other issues. I’m running the Sonnax Pressure Regulator Valve #22771A-02, a Sonnax Manual Valve #22771-09, Transgo shift kit, and a deep pan. Any chance this noise could be associated to these Sonnax valve parts being installed?

The Sonnax manual valve (part #22771-09) "allows fluid charging of the torque converter in Park position." The Sonnax Lube Regulated Pressure Valve (part #22771A-02K) "helps assure adequate fluid to the converter and works in conjunction with the new Sonnax manual valve."

This transmission only has about 400 miles on it after having to get it rebuilt do to a failed torque converter that sent metal through the transmission. Hoping the noise is normal and its just me being overly cautious! I have attached a video that should have the whirring sound present. Anyone more familiar with the inner workings of a TF999 have any insight?

*edit: nevermind, it will not allow me to upload the video. It’s telling me:

The uploaded file does not have an allowed extension
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