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Gabriel
Dodge Dakota
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9/04/2002
19:27:39
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 Subject: Drive-train loose
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Message:
Here is something that has got me completely baffeled. It is completely counter-intuitive!
I have a 2002 4.7 4x2 automatic with 3.55's, approximately 5,400 miles. The truck is a stock slt, no mod.'s.
The problem:
When I come to a stop there is a definite jerk in the drive-train. Usually it is felt approximately 2-3 seconds after the wheels come to a complete stop. It is not quite so noticable when decelerating from 50-60MPH or so, but I duplicate the sound/feeling at lower speed braking. Basically it feels like the drive-train is "taking up slack" after I come to a complete stop. If from a complete stop I allow the truck to "roll" forward, without touching the accelerator, about 5 feet or so, then brake, the [thunk] happens every time.
This would make sense if the [thunk] happened as I "accelerated"; as the drive-train took up slack while moving forward. But, when you brake the the drive train is already loaded. And would stay loaded because the vehicle is always in gear.
Any thoughts... this one has got me baffeled!!!
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smokem
Dodge Dakota
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9/04/2002
21:35:34
|  RE: Drive-train loose
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It may be the torque converter unlocking when coming to a stop.
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Gabriel
Dodge Dakota
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9/05/2002
12:20:33
| RE: Drive-train loose
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Message:
I had thought it might be something to do with the torque converter. So far that is the only idea that really makes sense.
I called the dealer last night and got the typical response:
"Haven't heard of that one yet, why don't bring it down so we can try to duplicate the symptom."
Yeah, then be without my truck for a week while the look for a problem they "can't find." No thanks!
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Cory
Dodge Dakota
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9/05/2002
14:49:38
| RE: Drive-train loose
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I've noticed something similar in my truck. I have a 2002 4x4 QC with the 4.7L and often times after coming to a stop (a few seconds after) I notice a thud. Really kinda freaked me out when I first got the truck because it feels kinda like someone just LIGHTLY ran into the rear bumper, kept on looking in the rear view mirror and seeing nobody there. On another thread there was talk about a vibration damper mounted in front of the rear bumpers on QC's so I've been wondering if maybe it has something to do with that (because on my truck it feels like it's coming from the rear of the truck). I never thought about it possibly being drivetrain related before.
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Gabriel
Dodge Dakota
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9/05/2002
15:27:57
| RE: Drive-train loose
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Cory,
Your description of the sound is exactly like what I feel. I feels like something lightly rolls into the truck. I will look into the "vibration dampner", but I don't think something like that would reproduce such a noticable, solid thud.
I am due for an oil change too, so maybe I will have a tech ride along with me when I do that and get their oppinion.
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silverD
Dodge Dakota
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9/05/2002
16:04:42
|  RE: Drive-train loose
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I have a 2000 4.7 Durango....same thing...slight clunck feel when stopped....no sound really. Any other ideas?
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R.L.Stuart
Dodge Dakota
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9/05/2002
16:18:50
| RE: Drive-train loose
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Fill you gas tank and see if the thunk goes away our tanks dont have baffles in them so at about 1/2/ of a tank you start to get a THUNK!
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Canucker
Dodge Dakota
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9/05/2002
16:27:40
| RE: Drive-train loose
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I'm just gonna throw this out there, but could it be the tranny shifting back into first? I know the wife's Civic does a similar thing when it goes back into first gear after a complete stop
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Lab Rat
GenIII
9/05/2002
16:53:16
| RE: Drive-train loose
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Haven't experienced this with my truck yet, but the wife's Saturn as well as my Rodeo used to do it. Kinda feels like being very gently bumped from the vehicle behind you.
Nothing ever broke on either, just got used to it.
Lawrence
Gibson Dual Sport, AirForce One air intake, Jet II, IAT, TPS, when are we gonna see some real parts??!!
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PJ
Dodge Dakota
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9/05/2002
17:14:12
| RE: Drive-train loose
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R.L.Stuart I was going to mention the same thing. Mine will do it from 3/4 to 1/2 tank.
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Anthony
Dodge Dakota
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9/05/2002
18:42:25
| RE: Drive-train loose
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Message:
Mine does this too, every once an in a while. My truck is 5spd, so it's not the tranny as mentioned!!! I think I read about this before and the cause was something that has to do with the suspensions.
Anthony,
www.geocities.com/dak2nv/
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TonyC
Dodge Dakota
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9/05/2002
18:47:24
| RE: Drive-train loose
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It's the fuel tank! With about 3/4 of a tank, stop the truck on a slight incline, roll the windows up, turn the engine off, then roll forward slowly and hit the brakes. You'll hear the fuel shoshing around and eventually feel the "THUD" from the gas hitting the ends of the tank. Because the tank is so long, and there are no baffles in it, the liquid is free to move around a lot.
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Gabriel
Dodge Dakota
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9/06/2002
12:01:06
| RE: Drive-train loose
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Tony C,
The feeling is not similar to a liquid "sloshing"... I know what that feels like/sounds like. My GMC had the gas tank directly behind the seat.
If it has something to do with the fuel tank, then the tank it self is loos and sliding forward or there is a brick in the tank that slides forward when stopping.
The ideas of the tranny shifting into first would be resonable, but it happens after the truck has stopped... then moves forward a few feet... then stopped again. The truck should not have left first gear while moving forward in this situation.
The idea of the torque converter unlocking has merritt. But, again, I am not sure the torque converter has time to "lock-up" while rolling forward a few feet at idol. Maybe I don't know the mechanics behind the torque converter very well.
The suspension idea is intriguing, I will have to think about that for a while!
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Lab Rat
GenIII
9/06/2002
12:44:37
| RE: Drive-train loose
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Message:
I disagree with the torque converter theory as well. If it didn't unlock during deceleration the engine would stall (had this happen on a GM product). I think it is inside the tranny, maybe something to do with a servo or clutch pack??
Lawrence
Gibson Dual Sport, AirForce One air intake, Jet II, IAT, TPS, when are we gonna see some real parts??!!
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Gabriel
Dodge Dakota
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9/06/2002
13:01:14
| RE: Drive-train loose
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Lawrence,
Out of curiosity... what does the "Lab Rat" mean. Lab Rat was the nickname given to those who attended the highschool I went to. You didn't by anychance attend the U of C Lab Schools did you?
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Ottawadak
Dodge Dakota
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9/06/2002
14:29:03
| RE: Drive-train loose
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Message:
My 2000 4.7 L with auto does the same thing occasionally. It doesn't seem to hurt anything. I've had people mention that it might be the axle wrap straightening out.
Cheers!
OttawaDak
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Lab Rat
GenIII
9/06/2002
16:38:23
| RE: Drive-train loose
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Gabriel,
That's funny, I picked that because it's an old nickname of mine from work (Lab Rat, Head Lab Rat, Chief Executive Lab Rat).
Later
Gibson Dual Sport, AirForce One air intake, Jet II, IAT, TPS, when are we gonna see some real parts??!!
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Bob W
GenIII
9/08/2002
11:59:29
|  RE: Drive-train loose
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Message:
Mine did the same thing for the first few months, maybe 5 or 6,000 mi. I haven’t noticed it lately it ether stopped or I got used to it (We used to call it the phantom bump.)
Gibson headers, Gibson Cat-back, Edelbrock IAS shocks, K & N drop in, 180 stat, Jet stage II chip, ARE Lid
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Unsatisfied
Dodge Dakota
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9/08/2002
18:33:40
| RE: Drive-train loose
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Message:
I have 1999 5.2l 4x4 CC has bumped me since new. I also thought I was hit from rear few times and looked but no car was there.
Note to self:
Never buy any of the following poorly designed products ever again;
Ford
Chrysler
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