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Discussion Starter #1
My 2006 Commander 4x4 with 3.7 L (27,000 miles) generally drives very well. On occasion I have experienced some strange behavior from the trans.

For instance, at low speeds (think stop and go highway traffic jam - say 5mph to 15), I will let off the accelerator and coast for a few seconds. When I return to the throttle (lightly...still in stop/go traffic), I feel a slight "bump" in the drive line.

I want to think it is "normal" for me to feel this, but it's not a smooth feel at all. It's a definite bump...not a clunk (no metal sound). I wondered Is this the trans shifting from 2nd to 1st? I hope to find out what others are experiencing...

There is no bump at all from a stop or very low speed roll. There is also no bump from acceleration over 20 mph (or thereabouts). Very smooth on both.

Any ideas??

Art Rummler
 

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Discussion Starter #3
U Joints a possibility, but with only 28k miles?

Doesn't seem likely. I just wonder if the gear ratios are such that when coasting (and still in Drive) that the application of throttle causes a slight torque grab in the driveline.

Or is this a characteristic of full time 4x4 which I am unaccustomed to...

Anyone a trans expert? Any techies out there? Love to hear from you all...

Thanks in advance.
 

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There are several experts around. Someone should be here to help you shortly. Would you like a cup of coffee while you wait? ...just kidding.
 

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It has been discussed on here that the sound is normal. You probably also here a clunk when you shift it from Park to Reverse and that is also normal.

My 2006 3.7 does the same thing once in a while, so far no problems.
 

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Discussion Starter #6
I don't really feel a clunk going into P or D.

I have noticed that on really FREAKIN cold mornings here in Chicago that the tranny seems a bit sluggish until warm. I now always let her warm up for at least 5 minutes in the winter.

No....my issue is the lower speed "bump" or maybe calling it grab or catch is more accurate. Not that I feel slippage....just that when coasting and then going back to throttle I get a bump. I don't feel that in my other car (Dodge Minivan).

So...anyone have an explanation....thanks!

AR
 

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Based solely on your description I believe you are feeling the driveline (trans,transfer case, front differential, rear differential) unload (off throttle) and reload (on throttle).
Your other vehicle does not have multiple gearboxes between engine and axles so it would not display this behavior.
Again, per your description, I believe there is no problem.
You might want to change your throttle lift technique (reduce amount of travel or speed at which you release or apply the pedal) to reduce or minimize this feeling.

Rob
 

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Discussion Starter #8
Thanks Rob. That is an excellent diagnosis. I really don't have any driveability issues. Just wanting to understand the way the Jeep works. First full time 4WD vehicle I've owned. And I must say I love the Jeep.

Mines the V6 and not trail rated, but it's still a great vehicle to drive. Especially in Chicago Winters!!
 

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artmanr-- I to have a 2006 3.7 and feel the exact same feeling you have described. I was actually going to ask the same question you just did. Luckily most of my driving is open road interstate traffic but when slow in the construction zones and city driving I feel the exact same thing with no problems, so far.
In addition has anyone felt a slight vibration in the gas pedal that that is off and on when around 40 mph-60mph going uphill or putting stress on the drive train????
 

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Trans noise

I have a 2007 5.7L Hemi AWD and have the same experiences...wondered if it was also a problem, but it only has 20k on it, and it is only at low speeds, just after letting off the gas to "coast" through a parking lott and putting some pressure back on the gas...it seems to "grab" harder. This doesn't happen when going at highway speeds or above 15mph. So, you are not alone.
 
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