So this past weekend I noticed that my trans is chattering as I'm slowing down. It shifts fine, but as I'm slowing down to come to a stop, I can feel the trans chattering in the 20-15 MPH range. Car is an 06 GXP just rolled over 60K miles, and to my knowledge, still has the original trans. Does anybody have an input on what could be causing this, and if its critical to be checked out. Thanks.

 

i would get the tranny fluid and filter changed to see what the fluid looks like. My GXP does it a little along with slamming into gear and all kinds of ****. My fluid was pitch black and a lot of shavings and tcc material in the pan.

 

i flushed mine at 60k and it was quite dark, but stick to simply changing the fluid

 

If it is only happening when slowing down at those speeds it could be from the engine switching from 4 cyl to 8 cyl mode instead of a transmission issue. I thought mine was the transmission at first until it only ran in 8 cyl mode due to an oil pressure sending unit going bad - once in 8 cyl mode it was smooth again.

 

15-20 MPH is too low of a speed for DoD to be disengaging. It would have disengaged around 45-50 MPH or so.

This sounds like it could be a TCC problem. I'd pull the pan and inspect for material.

 

alright, thanks for the replies. I have a trans-go shift kit and 8 qts of fluid sitting in my room waiting for a nice day to install. So I'll get that changed out and see what happens than.

 

My 08 Impala SS does the same thing when slowing down. It seems like its closer to 10 mph or less. All the rest of the time it seems fine. My trns has been flushed recently, there was no material in the pan, it was pretty dirty fluid though.

I hope someone figures it out, the local dealership can't feel it, imagine that.

 

Wrong. Before I had DoD tuned out, third gear would lug down to 12 mph while sounding like a chopper, since DoD was tuned out it hasn't lugged third. DoD isn't just for the highway. Mine engaged while doing even 20ish mph. Pretty much as long as it could get into third.

OP: Watch your RPM's when you feel the vibration end, they will rise slightly and the braking force needed to slow the car will be reduced slightly. All this can be felt and seen while driving.

 

The DOD system has many,many inputs and the Imp/Monte are different than the GP.
First is the system actually switching from 4/8, 8/4
Next one of the failsafes is the DOD does not function below 65psi oil pressure,(unless it has defaulted and shut off the fuel to the DOD), with that said if the oil pressure relief valve is stuck/sticking retaining above 65psi in the DoD system then yes it can and will remain on/delayed off.
The chatter at low speed as you say is/has been reported before, the sound is the timing chain slapping. There has been repairs due to the timing chain guide actually breaking and falling into the oilpan, there is a TSB for this.(not saying this has happened here)
You change your oil regularly but these engines are dirty inside especially the ones that use oil between changes, Recommendation here is to plan and do 2 oil changes, the first one should be with the same grade oil but use a diesel based oil for 500-1000 miles and then change it while hot for your standard gasoline base oil, synthetic or conventional. Between changes remove the oil pressure sensor (deep 27mm socket) and remove the DoD filter located beneath it, you can replace it new or just clean it with throttle body cleaner.

As for flushing the trans, it is a good thing "IF DONE CORRECTLY"
The pan must be dropped and the filter changed first.
Car must be run and at full operating temp ,fluids full, then flush with 16 qts in proper direction.
Then the fuse for TCM must be removed for 20 min. this will clear the adaptives learned, this is due to the removal of acess debris and new fluid.
Then you must drive "normally" for about a week for the TCM to relearn all the adaptives and adjust itself. (1 or 2 cycles just don`t do it) This is where tranny problems appear due to the driver input being to severe (agressive driving) due to it feeling good,persay!
Also be sure your induction system is spotless inside, it is extreemly important.

Also be sure to use the proper oil filter for the year LS4 engine, (VERY IMPORTANT)
The 05-06 LS4`s have a different oil system setup than the 07> and therefore use different oil filters. The earlier engines have an internal check valve (not in the oil filter) and the later models have no internal check valve, (it is in the filter)

 

It seems that GXPs and the Chevy sisters are programmed differently from each other, and that probably explains our different experiences. I think I read somewhere that you don't get DoD in third gear in an SS (either one).

Then I read Ill Born's post below, which pretty much confirmed it.

What he said!