came on here and did some research about the rearend clunk when taking off and i came to the conclusion that i needed to remove the rubber boot and lube mine. i removed the drive shaft and guess what , the drive shaft moved back and forth freely.now thinking that i have more serious problems with the rearend i decided to remove the yoke and replace the seal since i saw a few weeks earlier that underneath the yoke it was a little damp and at that same time i checked the gear oil and it was fine. i went to the ford dealer and bought the seal and the gear oil and a 6 ounce bottle of friction modifier which i already knew that you had to have on limited slip rearends. the service manager confirmed this by saying if you dont use the modifier you will eventually tear out your rear end. i got it all back together and guess what , no more clunk. it has to be the friction modifier. what else could it have been.

so if you have the clunk and cant figure it out .pump out some gear oil and add the $6 bottle of modifier , who knows it may be that simple.

 

had the clunk in mine and all i had to do was grease the slip yoke.. added more than needed and it was gone. also looking to drill in to it and add a grease zerk to it for in the future.

 

Is that just a clunk when you take off or get on it? I get a pretty solid bang out of my rearend when I get on it, same thing possibly?

 

mine was the same thing. when i took off and get on it after backing off than hitting the gas.

 

05 F150 FX4 78K miles.

Mine did it new, maybe 2,000 miles.
Dealership took a peek and lubed it, went away until.

Now (78K miles), Dealership took a look, lubed it and said there were some metal shavings but not that bad. They said I'd probably need a new Drive Shaft in a couple years. They said there wouldn't be a catastrophic failure but just more consistent clunking down the road.

I'm kinda pissed, this should not have happened at 2K miles or
78k miles. I would think that major part should last much
longer than that.

 

I am having this same problem with my 2008 AWD now for like 6 months... i just took it in telling i thought the U-joint was ging and they said they can;t find anything... could somebody tell me in point form what is is I need to tell teh dealer to check or do? gather somethign about a friction modifier and rubber boot,,, but that is all i gathered. thank you please

 

Hi.
I have the same thing happening to my truck when I take off from a standstill.

How exactly do you perform this procedure? I'm intrested in doing this.

Thanks for the great info., and thank you in advance.

 

Hi guys i had the same problem with my rear end it uses to clunck when i accelerated from stop and when i brake.. The problem was i the driveshaft is a two piece driveshaft and you have to put grease where both driveshaft connect to..you have to take off the 4 13mm bolts that connect to the rear end after you take them off pull the driveshaft out and you goin to see a rubber boot like a cv join boot so take one clamp off and leave one there when you take the clamp off the boot off you goin to see a connection like a cv join disconect boths part and put alot of grease inside and outside of the connection after that put the boot back on and put the 4 bolts back in and your problem should be fix..

 

To the OP, there's no way you can tell if the slip yoke is moving freely by pulling it in and out by hand. It binds under torque...way more than your arms can put on it.