I recently did a brake job for a friend on his 04 f-150 4x4 crew. Afterwords, a very slight tick could be heard coming from the rear end when braking with medium to hard pressure applied to the brakes. You cannot hear it until you slow down under 20mph. The rears got new rotors and pads. I triple checked these, and cannot find a problem. In an attempt to see what was going on, I put the truck on stands, took of the tires ( locked the rotors down with the lugs ) and then with a helper applied the brakes at the same time giving throttle to find the noise from the brakes. What we found seemed to be noise coming from the entire housing, and I also noticed what seemed to me excessive slop in both axle bearings. You could see the entire axle move about when the brakes were applied . There was a little in and out towards the housing, which is expected with the c-clip retainer. But you could lift up on the axle , feel, see and hear a thunk from the axle bearings. You could do the same thing pulling the axle to the rear or towards the front of the truck. I pulled the inspection plug in the diff, and found greyish crud stuck to the magnetic plug. I think this axle is eating itself up for some reason. He took the truck to the dealer, and they told him the "crud" was normal wear and without taking anything apart, blamed the brakes. They told him that if they take the brakes apart and find nothing wrong, he will have to pay the labor. I think this problem was there before the brake job, the owner just never heard it. ( he always has on the stereo) Anybody else with similar problems. Anybody know what the acceptable amount of play in the axles at the bearings would be? I have an 02 Superduty, and have never found anything near that much crud in the differential. I know they are different rearends. Sorry for long read.

 

Not being an professional mechanic, I would think they should only have a very few thousandths clearance. If they have as much play as you described, how do the axle seals not leak like a sieve?

Does his truck have a limited slip diff and yours not? The limited slip will produce more goop from the clutches than a plain one.

 

Gastic.....i have read of issues with premature wear on the axles where the roller brgs ride. As you may know, the rollers ride directly on the machined surface of the axle. They make a sleeve/brg kit for this, not sure if its dealer or aftermarket. It fits over the worn area of the shaft. Keeps you from buying a new axle. You wont find a good one in a junk yard. I dont know how to measure it or what is a maximum limit,, but if its not leaking oil, i wouldnt worry about it yet. I got a feeling what your seeing is normal wear. And, no the brake job wouldnt have anything to do with it. As you said,,he probably just started noticing it. And yes,,a small? amount of grayish sludge on the magnetic plug is normal. And yes, it makes a diff. if you have limited slip or not. If you think its really bad,,pull the rear cover and clean it out reall good, and put the correct synthetic oil back in there. If you have a lot of miles on it, it might pay to pull one axle and inspect the shaft. You might see evidence of excessive wear., or a rough or galled surface. Not good. Maybe someone can think of the name for that brg/sleeve kit. hope to be of some help...paul

 

Can't speak for you but mine started making noise not long after I got it. It wasn't a clicking noise it was more of a roar as a wheel bearing will make. The dealer replaced the guts through a TSB.
Don't know if it helps but that's all I got.

 

I was wondering if the seals were leaking also. Did you check the fluid level before you took the cover off?

 

Thanks for the quick replies. I will try to answer some of the questions.

The truck has 47 thous. miles on it. No evidence of any leaks, from the axle bearing seal, or vent, or cover.

I never removed the cover, just the inspection plug. It had about 1/4 to 1/2 inch of crud stuck to it, which is more than I can recall seeing on my own truck. The truck in question is Posi, as is mine.

According to his dealership, normal level for this rearend is 7/16 to 9/16 below the fill hole? I put my little finger in the hole and never could feel any fluid as far down as I could reach, but I did not measure how far down the fluid is.

I'm trying to help him out, but don't want to start tearing into this truck unless I have to. The truck is still under some type of warranty, and my initial belief was something was very wrong and told him to have it taken care of under the warranty, but I feel they are giving him the run around.

The TSB's I have found covers the noisy Trac-Loc unit. Which is affecting his truck, but I don't know if this is releated. I think that TSB is a nuissance issue, but not destructive, am I right on that?