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Ask Chris (aka- Moose) Your Own Question
Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Transmissions
Satisfied Customers: 1643
Experience:  16 yrs. experience with auto, manual, & CVT drivelines
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2006 Silverado duramax with Allison hard downshift when

Customer Question

2006 Silverado duramax with Allison hard downshift when almost at a complete stop..
Submitted: 8 months ago.
Category: Transmissions
Expert:  Jared D replied 8 months ago.

There are about 50 service bulletins from GM on these trucks that address a drive-line clunk either when accelerating or stopping. The nature of the drive-line on a transmission and engine with this much torque is to develop clunks apparently.

Is your truck 4wd or 2wd?

Customer: replied 8 months ago.
4 wd
Customer: replied 8 months ago.
this feels like a hard downshift when virtually stopped
Customer: replied 8 months ago.
already checked spline lubrication
Expert:  Jared D replied 8 months ago.

Do you have any tires that are slightly larger or smaller than the others?

You can check this by wrapping a string around each tire and making sure that there is no more than a 1" circumference difference between any tire.

Customer: replied 8 months ago.
no all tires equal
Expert:  Jared D replied 8 months ago.

Does it sound more like it's coming from the rear or the transfer case?

Expert:  Jared D replied 8 months ago.

Does it seem better or worse in 4wd?