Rear axle bearing fit question

[Scott_T]

I had a rear wheel bearing starting to make some noise and pressed the old bearing and retaining ring off. What I am seeing is that the diameter of the axle where the bearing resides is smaller in diameter than where the retaining ring lands. Measurement shows something in the range of 0.008" smaller diameter. This is a '72 with the small bearing rear end. Local parts house did not have the new bearing in stock so while waiting for it to show, I pressed the old bearing back on to see how it fits on the axle. As expected, it is a press fit over the region the retaining ring rests, but when fully seated, the inner race can turn on the axle shaft. From the surface finish, it does not look like this area of the shaft has worn to a smaller diameter, but I guess this is possible. Old bearing was certainly not in bad enough shape to spin the inner race on the axle but who knows what might have happened before I acquired it. Any idea if this smaller diameter where the bearing rests is normal?

 

[broncodriver99]

It should be a uniform diameter throughout the whole bearing/retainer area. It sounds like a bearing spun at some point. You should not be able to spin the race on the axle. Sounds like it is time to replace the axle.

 

[Scott_T]

Thanks for the quick response on this. Looks like it is new axle time...

 

[sprdv1]

Thanks for the quick response on this. Looks like it is new axle time...

always good to upgrade right

 

[rmk57]

Timken makes repair sleeves for worn or grooved axles. Should be more cost effective than trying to hunt down a used axle.

 

[Apogee]

Timken makes repair sleeves for worn or grooved axles. Should be more cost effective than trying to hunt down a used axle.

If you're talking about Speedi-Sleeve type products, those are designed to repair shafts for sealing surfaces, not interference fits between bearings and shafts. If that's not what you're talking about, then please disregard.

That said, you should generally have a light press-fit between the bearing and shaft. The retainer collar and shaft will be a relatively heavy press-fit. When removing the collars, I always cut them off with a chisel, otherwise installation and removal can and will wear out the axle quicker than necessary.

 

[Rustytruck]

Look into loctite 620 bearing mount.

 

[sanndmann3]

I had this happen as well. Ring and pinion guy said it was time for a new axle shaft. They are relatively cheap so I wouldn't mess with trying a band-aid repair...

 

[bronconut73]

/\This/\

Axle shafts for Ford 9" is the cheapest I remember in the last 30+ years. Quality has gone up but prices seem about the same as I recall in the early 90's.

WH has a nice selection of axles for front and rear.

 

[nvrstuk]

IF the inner race has spun on the axle shaft then it might have generated a bit of heat which could affect the steel hardness/brittleness...

I have seen so MANY rolled Broncos from an axle breaking directly under or within an 1/8" of the inner race that don't even think of not replacing the axle shaft...safety is so important and losing an axle brg is probably one of the most common causes of a rollover when it's caused by mechanical failure...

 

[Scott_T]

IF the inner race has spun on the axle shaft then it might have generated a bit of heat which could affect the steel hardness/brittleness...

I have seen so MANY rolled Broncos from an axle breaking directly under or within an 1/8" of the inner race that don't even think of not replacing the axle shaft...safety is so important and losing an axle brg is probably one of the most common causes of a rollover when it's caused by mechanical failure...

Any idea if this is a deal where the bearing goes out and basically grinds through the shaft at that point or are these fracture type failures in the axle shaft running is a good bearing?

 

[nvrstuk]

Bearing wears out...gets super hot, locks/freezes up and won't rotate-grinds enough of the axle shaft so that the shaft walks out of the axle housing


Bearing wears out...gets super hot, locks/freezes up and won't rotate-grinds enough on the axle that it gets it super hot over and over...at some point the axle steel grain structure has changed and it becomes brittle and eventually breaks..

I'm not a metalurgist, but I'm sure there's several possibilities...

...never tried to figure out which failure caused which rollover...

 

[Pa PITT]

I'm as tight as they come but it's time for an upgrade axle.

 

[DirtDonk]

Me too. And I sell them too, so can benefit from that side of the coin as well!
But no matter who's shafts you buy, anyone's (even old stock used ones in good shape) are better than a known buggered, and potentially future buggerer-of-Broncos any day.

So don't buy mine, but get a new one in at least that side immediately, if not sooner.
And while you're on this subject, pull the other side. They travel in pairs, cover the same number of miles, and are rarely very far apart in condition.
If you're in need of two, might as well know all about it at the same time.

How many miles on your Bronco? With either small or large bearing, but especially the small ones, your symptoms are classic buggered rear axle bearings. I bet the ones that fail probably made noise too, but the owner didn't bother to make note of it, or didn't hear it over the general din of the road.
This is exactly why it's so important we keep spreading the word, even to the old-time and experienced Bronco owners that might forget that these are wear items and need to be replaced every 100k miles whether they need it or not.
Again, especially the small bearings.

I'm sure it's just my luck in experiences, but even though I've seen both sizes wear out at near the same mileage, the only ones I ever dealt with that had failed catastrophically and lost a wheel on the highway were the small bearing versions.
Could be just coincidence, where that particular Bronco was overloaded too many times, or had more miles on them (usually failures happened by 130k and on the highway with an extra load in the truck), or bigger tires, etc. Or it happens that the small bearing models just need service that much sooner.

But at 90k miles, my large bearings were toast. Not making noise yet mind you, but loose enough to feel when doing a brake job and to resist rolling when the vehicle weight was on them.

So we're glad you found it when you did. Glad you paid attention to the noise and did something about it!
Now check that other one too please...;D

At this point in their lives (46 years in your case), the grease is probably dead anyway, and even if yours had low mileage, just driving it regularly at speed or under load could be enough to create problems.
But let us know what mileage you've got too anyway. Just out of curiosity.

Thanks

Paul

 

[edmedlin]

Agree with DD entirely, especially about checking the other axle. My bearing just went out (noticed a slight leak) on my driver side two days ago. Decided to check the passenger side and it had some play in it. Waiting on a pair of axle assemblies now..... I NEVER want to see an axle assembly passing me on the highway..