I''m looking for some advice please. First, the symptoms:

Some of you may have seen my recent post about raising the X. Its about 5" higher in the rear. Prior to raising the X, I had a vibration at around 65 to 70 mph. It felt like a tire was out of balance. Go a steady slower speed or a steady faster speed and it would go away.

Since raising the X, the vibration is gone, which I thought was cool. But now I have a "grind" type noise coming from the rear. I have to do all the testing on the freeway. There are no issues, no noises at regular street speeds.

On the freeway, when accelerating fairly hard up a hill from say 65 to 80, I can hear sort of a rumbly, grindy noise from the rear. Its not really loud but I can hear and feel it throughout the cab. If I coast at around 70-75 mph (just keep the speed the same) on flat ground, I can hear it come and go when the X is truly coasting for a few seconds. If I get up to say 85 and let off the gas, I can hear it as I decelerate until I get down to around 65.

This all only happens between say 75 and 90. I get no noise below 65-ish.

I had the drive shaft out over the weekend. The u-joints had no play and were free moving. I did feel the smallest play in the slip yoke, so I gave it a good greasing. That didn't change anything.

I'm guessing the problem is in the differential somewhere. I have not pulled the cover off yet to check the fluid.

I'm wondering if anyone can guess a diagnosis or point me in the direction of another ford-truck.com forum that might have more info?

Thanks!

 

Pinion bearings will usually create a "whine" noise, so I don't think that is it. A "rumble" sounds more to me like axle bearings. I've had the rumble before... it was at varying speeds for awhile, then went to mostly constant... it was the axle bearings.

Not too hard to do. Don't have to tear down the whole rear end or anything.

I'm sure others will chime in with better answers, but I would look to those axle bearings.

Good luck!

James

 

Thanks James! I'll read up on axle bearings.

I was going to pull the diff cover and see what I could see in the diff itself. Just need to figure out the quagmire that is the correct fluid mix.

I hope to hear other's noisy experience too.

 

It doesn't sound like the rear end to me. They make noise at all speeds above 20+- MPH if they are bad, either an on or off the gas gear noise or a bearing rumble. You could have wheel bearing metal in the rear end so I would look at the axle bearings first.......and the drive shaft.

 

Thanks! I guess I'm hopeful it's axle bearings as I can replace those myself. I'm pulling the diff cover on Thursday after the new fluid and permatex arrive.

 

Shake the yoke up and down just for giggles and turn it back and forth to check for any roughness. Also, when the cover is off put a large screwdriver/bar under the ring gear and pry up to check for looseness of the carrier.

 

I had the driveshaft out over the weekend and the u-joints had no play and were free moving. I greased up the slip yoke because I felt some play in there. Everything else felt fine where the driveshaft mounts to the transfer case and the diff. I will stick the X in neutral today and rotate the driveshaft. I spun the transfer case side the other day and it felt fine. I need to spin the diff side.

 

Pull down on the yoke with both hands with one+ wheel off the ground and turn it back and forth to check for roughness.

 

I will do that in a few hours at lunch.

It sounds like you're thinking the yolk could be worn out?

 

Well, the plot thickens. I jacked up one rear wheel and a couple of things:

1. its quite hard to turn the wheel in the air. I couldn't rotate the drive-shaft with my hands. I had to put a fair amount of effort into turning the wheel itself. I didn't hear anything but it was pretty hard to rotate it.

2. I grabbed the yoke and pushed it up and down and felt some play somewhere. Turns out the play is not in the drive-shaft. The entrance point for the drive-shaft into the transfer case has some play. I'm guessing there are bearings inside the transfer case and there's some play at the output. The output flange/shaft(?) wiggles up and down maybe 1/16th of an inch. Its barely noticeable to the eye but I could see it and hear the up/down movement and I could feel it if I pressed a finger up against the flange at the transfer case output.

Do I have a bearing issue in the transfer case?

 

There is a bearing in there and they should have no play. Take the front of the driveshaft of and turn the flange so you can get a better feel of it by hand. Take a look at the exploded view of it, I believe there is a ball bearing in there. (not sayin thats yer only prob)

 

While pinion bearings have higher pitch due to the 4x speed the carrier bearings do rumble and sound much like an axle bearing. (before the mismatch of gears sets in).

 

List: Transfer Case Output Shaft Bearing - 2002 Ford F-250 Super Duty | O'Reilly Auto Parts

 

Not to start an argument with Brent, but I have had just about the same amount play up and down on all five of the 4X4's I've owned on the transfer case output shaft. It never seemed right to me, but was told too many times by mechanics who were experienced that it was normal and within specs. Never liked to feel that play, but never had a problem with it either.

As for it being hard to turn the wheels... I'm assuming both were off the ground? I have always thought it was harder than I think it should have been to turn the whole drive train by hand. But again, never was a problem. I can't feel the resistance you are feeling, so I am flying blind here.

Hope you track it down soon!

James

 

I sure do appreciate the help. I disconnected the driveshaft at the tcase. I created a video to show the possible bearing issue. Hopefully the video will help. I first did a rotational test for heck of it, then an axial test. You can hear the play in the axial test.

Secondly, when I had the driveshaft disconnected, I did another rotational test, holding the very end of the driveshaft. I noticed that with the yoke extended, there was play in the slip yoke. With the yoke pushed in (shortened) there was no play. I just lifted the X and prior to the lift I had a vibration. After the lift I have the noise. Obviously the yoke is extended more now. I'm wondering if the yoke is the cause.

Third, I read on a Toyota forum that a lift can cause a worn tcase bearing to make noise because of the different driveshaft angle. So maybe it's the bearing.

Not sure what to do next...