Odd thump during acceleration
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Odd thump during acceleration
Hello all, new to this forum. Just bought a new 05 4x4 FX4 (leftover). Trucks barely broken-in (700 miles). I've noticed (felt) during acceleration, there is a "thump" while accelerating from a stop. Feels as if you had a tire in the bed, not tied down, that slid slightly forward during a stop, then slams against the tailgate when you accelerate.
This is more noticeable on harder accelerations than easy ones.
I've checked for anything loose, and found nothing.
I've read about other issues on here that are similar. However, those seem to happen more during shifts or at faster speeds.
Any ideas?
TIA
George
This is more noticeable on harder accelerations than easy ones.
I've checked for anything loose, and found nothing.
I've read about other issues on here that are similar. However, those seem to happen more during shifts or at faster speeds.
Any ideas?
TIA
George
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Joined: Mar 2006
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same problem
had the same thing happening with my 05 fx4. it really felt like there was some slack in the rear end when i accelerate from a stop. i took it in at 15,000 miles and they said they pulled the driveshaft and put some grease in the slip yoke. took care of it, but at 19,000 i could swear it is happening again. guess i'll hvae to knock some heads before the warranty is up.
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Thanks guys.
I looked up the TSB's and found bulletin "04266" that seems to be what the problem is. How do I find out what is req'd to fix this (prior to going to dealer)?
Thanks again
I looked up the TSB's and found bulletin "04266" that seems to be what the problem is. How do I find out what is req'd to fix this (prior to going to dealer)?
Thanks again
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Tuned
Joined: Nov 2005
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Originally Posted by FX4dude
No, it's not the clutch pack. I have a new Auburn LS ( carrier ) in my diff and i still have the thump.
I am going to try greasing the driveshaft splines - I believe this is the fix
I am going to try greasing the driveshaft splines - I believe this is the fix
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From: San Antonio, TX
It may be the fresh air vents on the back of the cab. Look between the cab and the bed. On the lower part of the cab you will see a black square. Look at it when you are slamming the cab door shut. You will see it open and close. When it does, it makes a thud. It will also do this when you accelerate rapidly.
4wd Low
Joined: Nov 2002
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From: Warrensburg US
Originally Posted by 03redstx
The driveshaft lube worked for mine for about a week, then I had the clutch pack replaced.
4wd Low
Joined: Nov 2002
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From: Warrensburg US
Clutch pack?
Originally Posted by 03redstx
The driveshaft lube worked for mine for about a week, then I had the clutch pack replaced.
Senior User
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guys have you ever look on the actual gap of your pinion gear set, co'z this is how i see it, the gears has gaps for expansion, a big truck with a lot of torque and a gap will make that thump, but if you drive slowly without slamming on gas see if it does that... once you build your kinetic energy a forward motion it will keep the gears intact....that's how i see it....i maybe wrong...
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From: Georgia
diff
I had the same prob, It does sound like the diff. I installed amsoil synthetic diff fluid and got rid of the violent thump/******/clunk. I can feel the plates slipping together but it is smooth and nomore thump/******/clunk.
I'm thinking if I added the friction modifier along with the amsoil diff fluid it may be perfect.
I'm thinking if I added the friction modifier along with the amsoil diff fluid it may be perfect.
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I'm not so sure it's gear lash. I understand what is said about a big truck with torque. However, (and I'm not trying to start a brand war pissing match), I also have a 2001 Dodge ram 3500 4x4. It has a Dana 80 posi rear. Last time I dynoed, I had 425 rwhp and 899 ftbs (yes, it has a Cummins). There are no issues with that truck like I'm experiencing with this new truck. I also converted the Dodge from an automatic to a 6 spd manual (myself) which included lengthing the front drive shaft and shortening the rear shaft. I experienced no ill effects.
With that said, I have been trying to see if accelerating differently makes a difference. Slower accels help, but if you listen, you can still hear the noise.
It almost feels like a brake bind, as if the rear pads are not releasing quick enough.
I'm going to the dealer tomorrow morning. Hopefully they will know what is causing this.
I will post again on Monday with what the dealer says.
Thanks again
George
With that said, I have been trying to see if accelerating differently makes a difference. Slower accels help, but if you listen, you can still hear the noise.
It almost feels like a brake bind, as if the rear pads are not releasing quick enough.
I'm going to the dealer tomorrow morning. Hopefully they will know what is causing this.
I will post again on Monday with what the dealer says.
Thanks again
George