Hey,
my truck (2004 fx4 l2 auto) makes ONE fairly loud metallic clunk intermittently. I can't totally recreate it on command but i can describe when it happens. Clunk typically happens when when i let off the gas right before an upshift from 1st to 2nd...so pulling onto a side street after waiting for a break in traffic for example. The clunk is definitely metallic sounding and I can sort of feel it as well as hear it. I have removed the drive shaft and greased the slip yoke, this is not a "thud" but a metallic clunk. I don't know much about U-joints but i have checked them for play and they seem fine to me, also there is no thud or clunk when going into gear, and they are quiet while driving. If i lie under the truck and lightly tap the driveshaft with a hammer it sounds almost exactly like what i experience. judging from the sound and feel of when it happens it sounds like it's closer to the tranny or transfer case than the diff but i dont know. Finally it doesn't seem to effect the driveability of the truck, maybe its even just driveline slack clunking together when i let off the throttle and it upshifts and the noise radiates through the steel shaft ( never had a steel drive shaft before, last ranger had aluminum). Any opinions are apreciated
-Jeff

 

Its the slip yoke making the noise but its the rear springs that wrap and unwrap forcing the slip yoke to make the noise.

You would be surprised how much the rearend walks up and down when power is applied on these trucks.

 

Hmmm ok so you're saying when I let off the gas and this happens its the slip yoke compressing till it sort of bottoms out and clunks? Makes sense I just didn't think it could be that since I had already greased it,didn't realize it moved that much
...if it is simply due to spring wrap and the slip yoke then it doesn't seem like much to worry about. Is there a solution? Possibly those jd trac bars?

 

Some say the track bars help, others say the cure is a Chevy spring swap.

I have no experience with either of them, my truck has had 3 drive shafts chasing this issue. After years of not worrying about this issues I have not heard it for a long time. I certainly have not greased the slip yoke since this shaft was installed over 130k ago.

 

Also check the carrier bearing (you probably do not have one) and the transmission mount. Blhde is probably right. I know you greased everything but it never hurts to do it again just for the excuse to get underneath and look around again.

 

thanks for the comments. I'll take a look under there again, probably going to give those jd traction bars a try, i've been looking for an excuse to get them anyway

 

ALot of rangers have a single metallic clunk noise from the output flange on the transfer case (Old TSB to replace the flange) you can remove the flange, clean the splines on the flange and the putout shaft, apply some green loctite 648 to the flange splines (NOT THE OUTPUT SHAFT SPLINES) and re-assemble. let it dry for 24 hours

putting loctite on the output shaft splines will allow the excess loctite to be pushed into the transfer case and well...you know