"Clunk" on takeoff

[Harley350]

My truck has done the same since new, now has 18K miles. I gave up trying to figure it out and forget Ford techs, "most" of them are shade tree mechanics who have no clue what the word clunk stands for. Good Luck!

[jascott]

I finally got this done. I ended up taking out all bolts at the differential and carriar bearing and then running the truck in 4x4. I kept my foot on the brake and just cycled between drive, and reverse a few times. Next, I used a prybar and the u-joint at the carriar popped back pretty easily.

I found the slip joing well lubricated, but I did add a bunch more grease to it. The grease in it was not broken down either. The dealer did tell me they lubed the slip joint about 10k ago, but I don't think they really did it.

Anyway, about 95% of my clunk at take off is gone, and I assume the rest of it is probably just driveline slack.

We'll see how long it lasts...

Thanks for all the help.

[melmount]

jascott,
what did you do? you lost me?

" I ended up taking out all bolts at the differential and carriar bearing and then running the truck in 4x4. I kept my foot on the brake and just cycled between drive, and reverse a few times. Next, I used a prybar and the u-joint at the carriar popped back pretty easily."

[jascott]

I took out the four bolts at the front of the driveshaft (where it connects to the carrier bearing) and the four bolts at the rear of the driveshaft (where it connects to the differential). The driveshaft would not budge, so I started the truck and put it in 4wd. I then shifting to D and R several times with my foot on the brake. By putting it in 4wd, this locks the front and rear together and prevents it from dropping the driveshaft and spinning it around. I read about somebody else doing this and it sounded like a good idea.

[jascott]

Well, the clunking is back and my AC is/was blowing hot air from the passenger side while cold from the driver side. I took it in to the dealer fo the AC and asked them to again look at the clunking. I also told them I had regreased the slip yolk.

This is the first time they have been able to "duplicate my concern." They have ordered a driveshaft from Ford and are supposed to be replacing everything from the transfer case back to the differential.

I'll update again after this is all done.

[ZeroOne]

Mine clunks on take-off as well... and also if you put it in neutral while coasting to a stop from above 15mph or so. Does it at the last second before stopping. Almost feels like the trans drags on the driveshaft for a second too, when it does it. Did it with both the factory driveshaft and the aftermarket that I run now. I think the trans does something funny, making the noise. Haven't figured it out though.

[jascott]

Well... I now have all new parts between the transfer case and the rear differential. That includes u-joints, carrier bearing, slip-joint, and both driveshaft pieces...

The dealer duplicated the clunk and ordered all this from Ford. I am somewha suprised Ford didn't tell them no.

I only have about 200 miles on the new parts, but so far, it is very smooth. Ocassionally, I can still feel a very small clunk, but I would say 99% of it is gone. We'll see how long it lasts...

[nccatfan]

Just throwing this out there, may be worth looking into if this happens again. What about the torque converter bolts? I've heard those occasionally come loose if not tightened enough.