Drilling Holes in Trailer Spindles

Ask the guy to make another one where the drilling process is cooled by liqiud over the part being drilled.

Mr. Del is known here as Dellori3. Quite a while back he proposed an oil lube system for boat trailer bearings, which I think is a basically good idea, and his system could work well, if fully engineered. In my experience, however, Bearing Buddies work just fine. (My boat trailer is about 30 years old, and receives little to no maintenance, and its bearings are still in good shape.) There is, no doubt, some depth at which the pressurization provided by the spring in a bearing buddy is inadequate to prevent water ingress. I, personally, have not found that point yet.

The thread you referenced is very interesting, and the CAD and FEA is impressive in the sense that someone was willing to do it for free. The holes are painfully obviously drilled in the wrong place, however. It is simply nuts to put them so near the location where the stress is already highest, and no FEA is necessary to know that the stress is likely to be highest just where it is. Even if the difficulties of drilling the angled intersection holes are overcome (and then making them spotlessly clean, so that some small chip does not damage the very bearing or seals you are trying to preserve) they would be far better placed if they were rotated 90 degrees fore or aft. I you are going to remove material, certainly it is better to remove it near the neutral plane rather than in the areas of significant compression or tension.

Modelling the load on the inner and outer bearings as being equal is probably incorrect for most trailer axles and wheel combinations. In many spindles, the vast majority of load is on the inner bearing, to reduce bending stresses.

Personally, I think it is profoundly foolish to have Joe homeowner drilling holes in his axles, given that you don't know who made that axles, and how good or rotten the metallurgy. (I don't want to point fingers, but we can all pick out quite a few countries where quality control is poor.) If this design were to have any success, then the entire stub axle would need to be engineered for the system, in which case drilling down the center of the axle would make more sense, as would ability to the debur, clean, etc., in a manufacturing setting. Personally, I would never feel at ease knowing that there are almost certainly chips present near my bearing and seals. What is one to do, when the tip of the drill snaps off just as it breaks through into the other hole?

It is very likely that if the metallurgy is good, (etc., etc.) the holes could be drilled and the axles would work just fine. But suppose the axle is already damaged, (with a developing crack) or that there is some huge porosity or inclusion, and the hole tilts the balance toward failure? A small company could be out of business; the owner would suffer the guilt of possibly having led to the death of someone as the trailer swerves into oncoming traffic, etc.

Some guy does the mod. The wheel falls off. Prove it's not your fault. Who wants to be in that situation?

I'd think that anyone obsessive enough to install such a system is also obsessive enough to (at very least) regularly feel the wheel hubs for heat, perhaps occasionally check for water ingress, etc. Bearings on a typical trailer will run just fine on a 50-50 emulsion of salt water and grease for quite a while. Ordinary simple maintenance seems to be all that is required -- and in my experience, even less than ordinary maintenance seems to work fine, with Bearing Buddies installed.

For me, the benefits of the system (and the required axle modification) don't come close to outweighing the liabilities.