Hi,
Bearing packing seems to be a popular topic. Here's my 2-cents worth. Car/trucks require bearing service about every 30-40K miles. Usually when the shoes were replaced. Why don't TT's require the same???? Maybe the bearings on a TT are put under a greater strain because of the weight issue. If that's the case then the bearings should be larger in diameter to take a greater load but their not so I'll assume the bearings are adequate for the load applied.
I am new to TT's but not new to mechanics. First of all I don't think the special hubs are much good. They will provide a way of getting some new grease into the bearings without removing the hubs. That is a plus but I am not convinced that the grease is actually getting into the bearing rollers and races. Secondly, packing a hub full of grease is not necessary and in fact the extra grease can inhibit the transfer of heat from the bearing and hub area. Think about this, the grease does not flow, move or shift from where it started. If properly packed it just stays there and does it's job. Putting more grease around what actually touches the bearings is not necessary. The consistency of the grease is what keeps it on the bearing surfaces.
Boats also use a similar packing method but they get immersed into water often and pushing some fresh grease (without water) is probably good. They also recommend repacking every year to get rid of any water that has accumulated. TT's don't fit into that catagory.
Here's the procedure I use and taught for 40 years. I hand pack the bearings by forcing grease into the rollers. I only use synthetic (Amzoil or Mobil One) grease. There's nothing better than synthetics and I want the best for lubing the wheel bearings. I do put a 1/8th to a 1/4" layer of grease inside the hub to reduce any moisture issues. When installing the nut I over tighten it with a ratchet while spinning the wheel. This assures that the seal is seated and also spreads the grease around. I then back the nut off and then finger tighten it until the bearing play just goes away. The specs are .001-.003. If you can feel some play that's OK. If you can adjust it so that all play is gone and the cotter pins fits that's even better. If the nut has to be moved to line up the cotter pin hole always loosen not tighten the nut. In that case loose is better than being to tight.
Here's what I am planning. I'll rotate tires every Spring to inspect tires and to even the wear. I'll probably re-pack bearings probably every 2-3 years.
I hope this information will help keep those TT's rolling a little more trouble free.
TeJay