Information on 2-3 Upshift or 3-2 Downshift Clunk Noise TECHNICAL SERVICE BULLETIN Reference Number(s): 01-07-30-042E, Date of Issue: May 21, 2007 Affected Model(s): 2008 and Prior Passenger Cars and Light Duty Trucks; 2003-2008 HUMMER H2; 2006-2008 HUMMER H3; 2005-2008 Saab 9-7X; with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32, M70) Supercedes: This bulletin is being revised to add the 2008 model year and 4L70E transmissions. Please discard Corporate Bulletin Number 01-07-30-042D (Section 07 - Transmission/Transaxle). Related Ref Number(s): 01-07-30-042, 01-07-30-042A, 01-07-30-042B, 01-07-30-042C, 01-07-30 -042D, 01-07-30-042E ARTICLE BEGINNING SERVICE INFORMATION IMPORTANT: For 2005 model year fullsize utilities and pickups, refer to Corporate Bulletin 05-07-30-012. Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift. During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case. This is a normal condition. No repairs should be attempted. Page 1 of 1 Information on 2-3 Upshift or 3-2 Downshift Clunk Noise -1999 Chevrolet Suburban K15.
Not sure but it sounds like you are describing this?
Tranny shop may be able to make an adjustment to lessen this effect.
Sunday, September 27th, 2009 AT 8:12 AM