Sometimes feel a bump from behind in the `06

[Quack_Addict]

I have noticed this several times myself but never really thought much about it until my wife said something about it yesterday. When at a full stop, in gear and on the brake (i.e. waiting for a light to turn), occasionally the truck bucks a little, almost like a car tapping the back bumper at really low speed. It does not happen consistently, just every once in a while. The first time it happened, I surely though a car had tapped me from behind -- but when I looked there was nobody there.

Any ideas???

[DmaxMaverick]

Sounds like driveshaft spline (output slip-yoke). Your dealer has a bulletin to deal with it. You'll get it lubed with special grease, and the problem should disappear for a while.

[paoutdoorsman]

I had a similar problem in my 98 Chevy Tahoe and it was driveshaft spline, however I did not hear it until I released the brake and began to accelerate. The special grease always fixed the problem for about 500 miles, at which point the grease had all dissolved/mixed in with the case fluid.

I was told I could upgrade to the 99 or newer slip-shaft yoke to totally resolve the issue... but it was 500 bones. I was told GM had nickel plated the slip-shaft splines to increase slipability/reduce friction thereby eliminating the problem. If this is still the same issue on an '06... shame on GM.

The trans shop that just fixed my leaky transfer case also looked a my Tahoe back when I had the problem. They knew exactly what it was, and mentioned to me that Ford had this same problem more so that Chevy and had provided them with the 'special' grease to apply to the slip-shaft splines.

Dana

[Kennedy]

CC Long trucks have 2 pc shaft and middle slip joint. My 2005 has started doing this (clunk) so I'm about to slather mine...