Hello. 2002 F350 7.3l ZF6 manual transmission -- Crew cab, short bed.

Ever since I bought the truck a few month ago, I've had a nagging feeling that there should not be as much free-play in the driveshaft as there is.

Example -- today I was diagnosing a different [possible worn motor mount] issue, and this is what I did. Put the truck in gear, stomp the brake pedal. Slowly release the clutch until truck almost stalled, and then stomp the clutch pedal to disengage engine from rear wheels. The resulting sound was a loud "clunk clunk clunk clunk" from the driveshaft spinning forward and backward.

Same thing in reverse gear. Put the truck in reverse, stomp the brake pedal. Slowly release the clutch until truck almost stalled, and then stomp the clutch pedal to disengage engine from rear wheels. Again, I heard a "clunk clunk clunk" from the driveshaft spinning forward and backward.

I had the rear differential cover off recently while changing fluids and the gear mesh pattern looked good.

If I park the truck on flat level ground, set it in gear, and turn it off -- I can crawl under the truck and use my hand to twist the driveshaft forward and backward. There seems to be quite a lot of free play in the rotation of the rear driveshaft before it contacts anything in either forward or reverse rotation.

Is this normal? I can take a video and upload/link it if it will help with diagnosis.

Thank you very much.

 

Yes! Please shoot and attach the video. Make sure the parking brake is working and set when you shoot the video.

 

I have a single piece drive shaft in my truck in my signature (similar to yours) and there is no play at all in the drive shaft. If I go under the truck and grab the drive shaft it doesn't even move but a 1/4" at most in either direction. What do the U-joints look like? If you have the single piece shaft then there should be 3 if I remember correctly.

 

Three u-joints on the two-piece shaft with a center support (or carrier) bearing between the two shafts.

 

Just grease the slip-joint and that should solve it!

 

What Whitey said. Cured my clunking drive shaft

 

Ford actually sells a small kit for it. It comes with a small pouch of Teflon grease and a new metal ring clamp for the rubber boot..

 

I was under the truck today and didn't feel much play in the slip joint. I held each side firmly and tried to rotate the other half in each direction and could barely feel any movement.

Last time I had the driveshaft out it had the blue rubbery stuff on the male end of the shaft, and it didn't look to be worn off anywhere.

I'm seriously considering that kit, just to rule out one more variable.

Here is video of play right next to rear pinion. Normal?

Here is second video of play at other end of driveshaft (transfer-case). Also noticed a scuff on underside of cab where it appears that the transfer-case driveshaft end was rubbing. I've noticed a strange noise while backing up with 7 tons on rear hitch in 4wd. Also the same chafing grinding noise of driveshaft rubbing on underside of cab while engine braking down a steep hill at 5mph (Low-range 2wd, hubs unlocked).


Thank you all for the words and guidance.

 

I suspect that the driveshaft clunking I'm hearing is due to stomping in the clutch while the driveline is still under a lot of torque.

Imagine towing 7 tons in first gear at 10mph -- then mashing the clutch pedal to the floor without releasing the throttle pedal. "Clunk clunk clunk clunk clunk" -- Sometimes as many clunks as seven.

Sounds like the driveshaft bouncing forward/backward against the rear wheels and that tiny amount of free-play. I will try to take another video. From the noise, it sounds as if something is going to tear itself apart.

 

Each one of your videos is set to private...at least from this computer.

 

Should be viewable now..

 

Anyone? Thanks!

 

thread to top....

 

Mine never did it till John Woods worked on it. Now it dose it too. I haven't looked into it et but when I do I'll report back. It's to hot fo9r me now so next fall.

 

I hate to bring back this old thread, but did you ever discover anything about this? Mine with the 5.4 has this exact same thing. I assumed it was normal, but now I don't know