Hi folks. I purchased a 2000 F350 4X4 ECLB a few months ago. Upon doing a real good inspection I noticed the carrier bearing was bad. The bearing was replaced today. Once replaced the vibration actually got WORSE and not better.

It got me thinking that the driveshaft had a lot of play previously and probably gave in to helping what could have been bad/seized u-joints?

The new carrier bearing doesn't allow any up/down movement on the driveshaft and the overall pinion angle looks decent to me.

Can bad u-joints cause this severe vibration I'm experiencing?

Thanks in advance!

 

Yes, a bad U-joint or double cardan joint can do this.

A seized slip joint can also do this.

 

umm...... I've never heard of a cardan joint or the slip joint. I guess I will start with the u-joint(s) and see if they help me then go from there. sound like a good plan?

 

Your slip joint is where the drive shaft plugs into the transmission. Grease it lightly.

A double cardan joint looks kind of like a double U-joint.

 

thank you!

 

UPDATE: Since posting this, I've done the following things:

* Replaced carrier bearing
* Replace all u-joints
* Removed the shims on the carrier bearing. Had approx 2" of shims and I noticed the pinion angle was FUBAR.

Good news! I no longer have the dreaded shudder/vibration upon take-off.

Now I do have a slight wobble/vibration around 45mph but have noticed there are lots of folks that experience this issue.

I plan to have the driveshaft balanced as soon as I can. Also after thinking about it more last night and driving, I threw the truck into "neutral" and a lot of the vibration that I"m experiencing went away. Do you think the balancing of the driveshaft will help?

 

In theory, if the vibration was caused by the drive shaft, putting the truck in neutral and coasting would not change the vibration. You're disconnecting the engine from the equation, not the drive shaft, axle or transmission.

What you sense as a "slight wobble/vibration at 45 MPH" may in fact be a slight misfire.

 

Understood on putting in neutral would not change the vibration, however, I was just really trying anything and grasping at straws. Ever since purchasing this truck it's not been a lot of fun troubleshooting these irritating items I'll tell you that :-(

If I had a slight wobble/vibration @ 45mph and was a slight misfire, wouldn't it throw a code or something? I have a scangauge II on the truck and check for codes often (every time I drive it) and it has thrown no codes to date.

 

It takes a lot of misfires to actually throw a code and light the CEL. You almost have to have a dead cylinder for the CEL to illuminate.

The key is to have the truck scanned for PENDING CODES. If there actually is a misfire, the pending codes will point you to the offending cylinder.

 

Understood. We are referring to a diesel engine like I have (7.3L), correct? I guess the scangauge would not give me "pending" codes, eh?

 

Oh, well scratch the misfire then. I was thinking of a gas engine.

 

LOL I can troubleshoot a gas engine no problem.

Thanks for your help!

BTW, thinking out loud.... there isn't any real "Load' on the truck when in neutral vs. when in Drive. I am still wondering if my issue is all driveshaft/pinion angle related.