Probably most medium size trailers have the 3500lb axles and 10" brakes. The design of the spindles has little to no shoulder to locate the inner bearing. When I looked up the blueprints, I found that the spindle shoulder has a contact area against the ground surface of the bearing of about .020" and can be as little as zero using the print tolerances. That extremely small contact area can cause burrs, seal damage, loss of bearing adjustment and bearing alignment.Today, I pulled and serviced all four hubs and found contaminated grease in two of them. The metal wearing away from the spindle contact area was the issue. The ground surface of a bearing is where it is to take the load, not the roughed in clearance radius.To show you what I am talking about, in this photo is the blackened grease and a narrow band of metal which is the contact area that takes the lateral load of the trailer. Here is a photo showing the result of the bearing radius carving its way into the spindle shoulder.This photo shows the bearing with bluing so that the contact area can be found. Of course the bearing is on the spindle backwards for its photo op. The narrow dark blue band is the only support designed into this spindle. The lighter blue areas are where the roughed in radius is now locating the bearing.I do not have an easy fix for this design fault. Short of replacing the axles with 5200lb units, all we can do is frequent bearing cleaning and repacking. For those that choose to use the grease fittings, just remember that the metal shards will be pushed to the outer bearing and the bearing adjustment still needs to be done frequently.Here is a view of the metal shards I am talking about:

Interesting report. A little disturbing too.

Thanks for sharing. I have 3500 lb axles. Good to know where to look. Might also explain why I have had issues with 2 axles. When I repack in the spring I will have to take a close look. I don't remember mine having this issue when I clean off the grease. I would think the cloth would stick to the metal burrs when wiping off. Guess I just need to make extra sure.

Were the bearings tightened properly? Looks like the inner race was turning, and it is not supposed to do!

The seal surface seems to be a pressed-on sleeve. Could a person not pull the spindle and face back the shoulder slightly to allow the inner race to seat on the seal sleeve? GD

The seal surface is not a sleeve, it simply is too small in diameter giving virtually no support to the bearing. Even if the shoulder could be trued, you would be back to basically a sharp corner as the only lateral contact between the bearing and the spindle.When a bearing is manufactured, the steel blank has the radius cut in so that area will not be touched by the finish grinding operation. That surface is not expected to be used and may not run true, it is just clearance for the spindle radius.There is nothing to stop a bearing from turning on a spindle, as you know, the bearings are a slip fit on this type of axle. With the extremely small shoulder contact, bearing adjustment is lost in short order. The seal inside diameter should be 1/4” larger giving full support to the bearing.This is a #84 spindle and is used by all the axle brands, it is poor design and has nothing to do with the quality of my work. I posted about this several years ago, only to have the thread locked in a matter of hours.

3500lb axles bad design | Good Sam Community

keymastr
Explorer
Feb 21, 2018
In that drawing R is a radius, not a measurement of a contact surface. Just describes how sharp the curve is.
mike-s
Explorer
Feb 21, 2018
keymastr wrote:
In that drawing R is a radius, not a measurement of a contact surface. Just describes how sharp the curve is.
R is a maximum radius. It places a limit on what material can be removed. This might help you understand:

That 1/2" in the leftmost drawing? That's the radius, and not coincidentally, also the distance beyond which no material has been removed. They're one and the same for a right angle corner.

Here's a rather large image, which may make it even easier for you to understand.
Lynnmor
Explorer
Feb 21, 2018
I have done the research, the math and the actual measurements, if you think that the tiny surface is sufficient, fine. One thing that should be considered is that the load is not even across the entire area due to clearances and attempting to find the yield is just a guess.
Lynnmor
Explorer
Feb 21, 2018
Here is a photo of an actual bearing, it measures 1.651" where it contacts the shoulder. Note that the manufacturers undercut the radius area so that the surface to be ground stands proud and eliminates increasing the contact area. The pictured example is one of the better ones that I have seen.
RinconVTR
Explorer
Feb 21, 2018
Interesting thread. I do not see any problem at all.

Except for the person who said the inner race is suppose to spin...yeah...that's wrong. The inner race is NOT suppose to spin on the axle under load.
mike-s
Explorer
Feb 21, 2018
Lynnmor wrote:
Here is a photo of an actual bearing, it measures 1.651" where it contacts the shoulder.
OK, so the shoulder (1.72) minus your measurement (1.651) = 0.069 difference in diameter, so the overlap is half that, 0.0345. From the drawings, I came up with 0.032 as a minimum.

So, what's your point, and explain why no one else is having this problem.

Oh, and what did you base your claim about the contact being "about .020" and can be as little as zero using the print tolerances." What has a tolerance of .020, or even .010?
Lynnmor
Explorer
Feb 21, 2018
mike-s wrote:
Lynnmor wrote:
Here is a photo of an actual bearing, it measures 1.651" where it contacts the shoulder.
OK, so the shoulder (1.72) minus your measurement (1.651) = 0.069 difference in diameter, so the overlap is half that, 0.0345. From the drawings, I came up with 0.032 as a minimum.

So, what's your point, and explain why no one else is having this problem.

Oh, and what did you base your claim about the contact being "about .020" and can be as little as zero using the print tolerances." What has a tolerance of .020, or even .010?

My point is that folks like you never recognized the issue and go about their merry way not knowing or caring about things mechanical. As long as the telephone poles keep coming at them, they never had a problem. I show actual photos and describe what I see and, for some reason, I am the villain. But I knew before posting that the finger pointers would come out in force.

You neglected to take into account the radius on the spindle shoulder. You also didn't understand that I said it was one of the better samples that I measured.

Now the real question is why would anyone take such things personally and come to the defense of such a marginal design.
mike-s
Explorer
Feb 21, 2018
The design is fine. It's just you.
Lynnmor
Explorer
Feb 21, 2018
mike-s wrote:
The design is fine. It's just you.

Here is a bit more, if you can stand it:
time2roll
Nomad
Feb 21, 2018
So get new spindles already. What brand are these with trouble?

The grease on my AL-KO 3500 axles was mostly red after 10 years.
I saw no issues on mine.