98.5 2500 4x4, stock.

A couple of weeks ago I noticed a rattle. It went rattlerattlerattlerattle as I drove down the street. It sounded speed related, was not very loud, and seemed to go away with the use of the brakes. To some extent it also seemed related to the road surface, it would make more noise when the roads weren't so smooth. In fact, it sounded like the noise that other people's cars make when the drive by- you know, kind of like they've got rocks in the hub cap.

So, 1,500 miles later, it's now a loud metal-on-metal sound. It's like something metal is dragging on a rotor or drum or is stuck between a brake pad and the rotor. Also, I had my wife drive next to me and it's definitely coming from the front of the truck somewhere.

Braking ability and the feel in the pedal is unchanged.

I have:

• Removed both rear wheels and drums and inspected all associated parts and found nothing out of the ordinary.
• Removed both front wheels and calipers and inspected and cleaned all associated parts and found nothing out of the ordinary.
• With the calipers off, both front hubs spin freely without grinding, and I can hear the straight cut spider gears in the diff. doing their thing when I spin the left hub. (right hub has that vacuum disconnect thingy between it and the diff.)
• Inspected the front drive shaft (as best I can) which spins freely and has no noticeable u-joint or bearing issues.
• Opened the fill hole on the front differential and confirmed adequate fill and quality of oil (still yellow)
• Inspected between the backing plate and rotors for debris.

Looking for suggestions/comments/advice.

Thanks in advance.

Tom

 

Have you checked the axle u-joints? Pry on them, look for movement and disintigration- my right side had chewed up the cups, had tons of movement, and had eaten all the needle bearings. Lots of movement.

 

with the truck jacked up, try wiggling wheel at 12 and 6 O'clock , and then at 3 and 9 o'clock, any play will indicate ball joint or wheel bearing failure.

 

I know that this sounds stupid but check the break pad dust protectors. I had a grinding in the front end and found that it was the rusted out dust protectors that were rubbing on my brake drums. I bent it out and I havent heard the grinding since.

 

So against my better judgment I drove it. A lot, and under different driving conditions. Then I let the Mrs. take it for a spin to get her impressions of the sound. Then I parked it for a couple of days while I thought about it.

It sounded to me like a bearing race spinning. With my foot on the pedal- no noise. Under light load or no load, it rattled, then it all stopped under about 15 MPH. In or out of 4WD it was the same. You know when you spin those cheap plastic caster wheels that don't have bearings but just a smooth shaft, and instead of spinning on the shaft they kind of rattle around it and make the high pitched vbvbvbvbvbbvvbvbvb sound? That's what it sounded like to me, and I was pretty sure it was occurring at drive shaft frequencies. This lead me to believe I was dealing with a pinion bearing, and output shaft bearing or the support bearing in the middle of the shaft.

I jacked up the rear of the truck, put the case in neutral and spun the wheels. The posi worked well with and the rear end had no noticeable grinding or noises. Driveline lash seemed acceptable and the pinion displayed no signs of compromise.

U-joints were good.

I moved up to the support bearing and noticed a slight metal fleck on the shaft in front of the bearing. While inspecting the bearings integrity I found the culprit. It appears to be a dust cover for the front of the bearing. It's a tall, stout ring that appears to have been connected to the bearing. It is not now and there's evidence that it's been spinning on the shaft and banging back and forth on it. Here's the picture:



When I spun it, I knew I had it:
http://www.youtube.com/watch?v=rAkyI4r0IUE

Obviously it serves a purpose. The shop manual isn't much help. I may just cut it off in the mean time.

 

Okay, so I've been perusing the shop manual, which is completely useless for this issue.

Is this ring supposed to be attached to the bearing, or the drive shaft as it's color suggests. Is it some sort of spacer, so to speak, that keeps the drive shaft from sliding too much? It's not clear to me where this belongs.

 

cut the ring off,(dust sheild) it looks like it seperated, its gonna cause more damage spinning round on the shaft than it will if its missing I believe the dust shield is pressed onto the drv shaft, not onto the bearing its self.
if you remove the rear 1/2 of the drv shaft be aware that you can install it 180* out of phase, the slip joint does have 2 master splines, so mark it before seperating
usually when a hanger bearing goes bad you get a thumping/vibration under take off, and it lessens as the load comes off the drv shaft

 

Thanks for the info. I'm wondering whether it would be less trouble for me to just weld a couple small pieces of rod to the ring and the drive shaft and leave it in place than to cut it off. It looks like cutting it is going to be a PITA. OTOH, I could just tack that thing back on and make it as balanced as possible pretty quickly and pretty easily.

What do you think? (in the mean time, I've found the 1002nd use for duct tape.)

 

tack weld would work as well, doubt it would affect balance

 

Thought I'd post the fix for those who are interested: