I am just dumbfounded. On my last X, i fought driveline vibes from the day i bought it. Did everything possible. The one I have now has had zero vibes- until now. We are leaving on vacation tomorrow night. With time at a premium, I bit the bullet and had the local dealer replace a badly leaking rear pinion seal and change the rearmost ujoint. I had replaced it once after I bought it with a cheap Chinese made joint. I broke a needle bearing and had to use some old ones from the original joint. Needless to say, I checked it two months later and it had some play-but no vibes. Anyway, i marked the driveshaft on both ends prior to taking it to them. As soon as i picked it up and hit 65 mph it started humming in the rear. It "peaks" out noise wise at 80. Anyway, got it home, seen they didnt use my paint lines and reinstalled the driveshaft. While I was at it, i noticed the pinion is much harder to turn than when i took it to them (148,000 miles of wear). Do you think they crushed the sleeve too much and gave it too much preload? They put in a beefy Spicer joint. I know it was smooth when i took it to them. They are willing to work on it tomorrow but I am leaving tomorrow night. Any ideas?

 

Have it at the dealer when they open, bring a box of donuts for the techs and tell them you have to have it back by 3PM (or whatever time). The nicer you are the more they will care and the donuts will go a long way.

 

The service department has always been good to me. They even offered for me to leave it today (went up on my lunch) and they would bring me back to work. Donuts wouldnt hurt either.

 

The nut on the pinion has come loose twice on mine causing vibration. Now it's doing it again. Could be that simple??? Good luck and let us know.

 

Sounds like too much preload on the pinion. Probably used an impact and just hammered it. I usually just count the exposed threads and retighten the same amount. I know it's not the correct way but after several dozen I've never had an issue.

 

I would bet you it started leaking because of a bad pinion bearing. Those seals always go out for a reason. Since I went to the same school he had available, probably anyway, the tech should have known that.
They at least overtightened it or missed a bad bearing. Maybe both. It's rare that a seal goes out back there for no reason.
Also check to make sure your rear end oil isn't milky. That's the most common cause of the bearing going out.

Also those alignment marks you mention don't matter one bit. The driveshaft is ballanced as an assembly. It's not attached to the rear end when they do it. Axles and gears are ballanced by themselves at the manufacturer. Nobody on the assembly line ever paid any attention to alignment marks outside of each individual part.

 

I've posted my story on here a year or two ago chasing a vibration. I had my pinion changed, ujoints, my driveshaft straightened, etc. Ended up being my driveshaft was bad. The front of the shaft is splined. I took it off one day and noticed that the splined portion in front was loose...I could move it (flex it) a small amount. I ordered a replacement from a place in Texas (cheaper and stronger than Fords) and my vibration was gone. It's not hard to remove and replace this yourself if yours is bad.

 

Thanks guys. I have been intimate with Excursion drivetrains since my last one vibrated so badly. I even completely rebuilt the rearend. Nothing fixed it. In the case of my current one, It had zero vibration when I took it to them, so I dont think the driveshaft is bad. The pinion is super tight. the service manager said they used an in/lb torque wrench to check the drag. They did not change the crush sleeve so I know it has to be tighter than when i took it to them. It is there now and I am curious as to what they will say.

 

Quick update. Dealer had the X all day. They said the pinion force was well within spec and could not find anything wrong other than the muffler is rusted out. The service manager said if you get it to the speed the noise occurs and put it in neutral it goes away until you rev the motor to 2,000 rpm.
Yeah, he actually said that. Anyway, I have to pick it up and head out tomorrow for the beach. Will post once (if) I get there.

 

99 f350 50k
01 f350 90k
03 x 202k
97 f150 140k

had to have the pinion seal replaced on all of them.

 

Well, made it to the beach. Same exact trip as last year but different Excursions. I do love the difference in mileage- made it here in a little over half a tank. The bad thing is, I thought this trip would be more pleasurable due to no drivetrain noise. I honestly believe the pinion bearings are gutted and hope it gets me home. I have lost respect for my favorite service manager. The thing that bothers me is he knows I am not the typical customer that would buy the muffler causing a rumbling sound in the driveline. This noise does not appear to be the same as the V10. It starts at 60 mph. There are times it is almost dead quiet. Loading the drivetrain and even sometimes unloading it to find the sweet spot definitely changes the harshness. If it gets me home, I will tear into the rear and try and find a LSD. Again, this X was super quiet in the driveline before this work. On my last one, I never heard it quiet so I always wondered if it was normal for the X. On this one, I have a head start because it was quiet and I loved the fact that it was. Anyway, I'll keep you updated.

 

Guys- just an update. Since the trip, my vibes have dropped into a rather narrow speed range. 62-70 mph. When I got it back, I had found the rear yoke on the pinion side of the driveshaft was 180 degrees from my mark. I basically put paint marks on both companion flanges on the same side of the driveshaft before i took it to them as I was the first one to ever have removed the driveshaft. It shouldnt have mattered, but it bugged me to the point that last night I removed the driveshaft and knocked the ujoints out on the flange so I could get it back to the original marks. Drove to work this morning and now I can not feel it at all, but can only hear it very slightly if the radio is off and at 65-67 mph. Good enough for me. These vehicles are by far the most sensitive I have ever seen regarding vibrations from the driveline. The wife thinks I am crazy.