Dave
I agree with you, I have never gone the route of just adding grease. Any contaminants will end up at the exit or pushed toward the back of the inner bearing.
Three pumps on the grease gun (full size) is actually almost too much.
The cavity is generally empty when new. MFR costs.
Manually palm grease the old traditionally way. IT is not a boat launch in the water.
Grease seals are cheap. But if you over do it. It ends up on the brake drums and shoes. This causes sticking (just the opposite of lubing) And internal heat to the drums and shoes. IF let go long enough. it will destroy the hub and bearings from heat. Shoes are shot without even damage to the drums but they are overheated also and should be replaced. The spindles are part of the axle. Now you need new Axles as well as drums and shoes provided you haven't overheated the magnets also. So a hundred dollar DIY job has now turned into a 8K job for replacement parts to make it right again.
Nothing can be better than removing the old grease and replacing it with new. It is like adding more oil to an engine to an overflow and expecting the old oil to be removed while adding more new oil.
Quote:
Originally Posted by Dave W
I do it the old fashioned way and have since --- well as long as I've owned a towed trailer.
There are a couple reasons, well actually more. The first is that it takes at least a full tube of four buck/tube grease to lube those bearing and fill the hub initially. Then if you really want to do it right, you still need to pump at least a half tube of grease back in there every time you get the urge. That discolored grease that you see oozing around the spindle nut washer (yes, the washer, not the Zerk) is only from that outer bearing. You can only guess where that cruddy stuff from the inner bearing goes. Yep, it mixes with the new and helps keep that hub filled plus adds a bit of unsprung weight.
Then there is that seal. It really is not a very good part and the land that it rides on plus the land behind it are pretty small for what they need to do to prevent fouling the brake shoes and magnet surfaces. Take a look at the attached photo. This is a brand new spindle on a 6K axle. Larger are virtually identical and you will see the seal surfaces - the last one before the forging flaw ith the grease hole just in front of that surface. Not noch height to restain a seal - lesss ten .0625 (1/16").
Repacking wheel bearings (and inspecting brakes) is NOT a nice clean project. It does take some time and can be expensive if you are not a DIYer - but still better then sitting along an interstate in West Overshoe on a Saturday evening with a smoking hub.
Your choice on how you want to lube bearings. But as always, the above is only my opinion though based on my many yeras and many miles hauling an RV. I have even gone to the (minor) cost of plugging the wheel's hub caps hole with a part from etrailer.
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