grease in wheel hub

[mbaker]

Just curious how others do this. I know there are multiple discussion on boating forums about this and with the greasable spindles on other trailer types now it seems an awful lot of extra grease is needed to pack the hubs full of grease either when repacking or when greasing through the spindle either one. I've seen the discussions in favor because it keeps water out, and I've seen discussion against because it runs hotter with no expansion space. To me good seals and caps take care of the water issue so then it just means you have to take it apart to get new grease in vs being able to pump grease through so is it just a convenience thing?

After cleaning I have always smeared a thin layer of grease on the inside of the hub to protect the bare metal, maybe a little thicker near the races, packed the bearings and smear some extra grease behind the inside bearing before installing the seal. I don't know if it makes a difference or not but I feel like this would help if there was some water intrusion to stop it before it got to the bearing itself. Then I reach through the bearing and build a little dam of grease up next to the bearing (inside and outside) before installing the hub on the spindle. Never had issues and for the most part the grease is still in the same spot when I take them apart. This takes about 3/4 of a tube of grease for 4 hubs, if I was packing them full it would take a tube per wheel it feels like.

That has worked for me on any bearing I have packed in the last 30 years, but perhaps I am missing the boat on not filling the hubs more even if not completely full. Street car, race car, truck, trailer, farm wagon etc, all got the same treatment.

 

[Lubener]

I have always put a thin layer of grease in the hub to the level of the races. It being there keeps the grease from migrating away from the bearings and into the hub area.

 

[D60]

Just curious how others do this. I know there are multiple discussion on boating forums about this and with the greasable spindles on other trailer types now it seems an awful lot of extra grease is needed to pack the hubs full of grease either when repacking or when greasing through the spindle either one. I've seen the discussions in favor because it keeps water out, and I've seen discussion against because it runs hotter with no expansion space. To me good seals and caps take care of the water issue so then it just means you have to take it apart to get new grease in vs being able to pump grease through so is it just a convenience thing?

After cleaning I have always smeared a thin layer of grease on the inside of the hub to protect the bare metal, maybe a little thicker near the races, packed the bearings and smear some extra grease behind the inside bearing before installing the seal. I don't know if it makes a difference or not but I feel like this would help if there was some water intrusion to stop it before it got to the bearing itself. Then I reach through the bearing and build a little dam of grease up next to the bearing (inside and outside) before installing the hub on the spindle. Never had issues and for the most part the grease is still in the same spot when I take them apart. This takes about 3/4 of a tube of grease for 4 hubs, if I was packing them full it would take a tube per wheel it feels like.

That has worked for me on any bearing I have packed in the last 30 years, but perhaps I am missing the boat on not filling the hubs more even if not completely full. Street car, race car, truck, trailer, farm wagon etc, all got the same treatment.

I basically agree with everything 100% and do the same.

That said, I don't have a boat trailer and all I know is the old rule about the best days being the day you buy it and the day you sell it

 

[mbaker]

Yep… I think that can apply to lots of hobbies.

Ive always tried to keep good seals on them and keep bearings adjusted up as close to zero end play as possible so everything ran true and the seal didn’t get cockeyed on the spindl. Inherently though I think more service intervals are required because you are submerging them completely. I Have never had water issues internal to the hub, I’m sure some small amount eventually seeps past the seal or cap though. I would try to do the same with every trailer you just don’t have the water issue.

 

[Kestas]

That's exactly how I would do it. I want to mention that the seals can generally withstand 2 psi pressure. This is important to note since many boaters submerge their trailer hubs in the water soon after a long hot drive. This quenching can suck water in past the seals. If you have the luxury of time it is better to let the hubs cool off before launching the boat.

 

[mbaker]

I’ve seen that mentioned before about the suction but I have calculated it before and assuming you start at zero pressure over a 60 degree change, there is about 0.1-0.2 change in pressure up when running and back down when cooled off. Even if the hub equalizes to outside air at running temp you are talking the same 0.1 negative pressure cooled off. Maybe someone has better info but it doesn’t seem like an issue to me.

 

[Donald]

So there are a few different systems for lubricating the bearings in a boat trailer.

1) the basic roller bearing with a steel center cap.
2) the basic roller bearing and the center cap has a grease fitting on a spring loaded center plate
3) the basic roller bearing, the center of the axle shaft has a grease fitting and has an opening for the grease to flow to the back of the bearing where new grease pumped through grease fitting l pushes old grease out
4) a fancy roller bearing where they say to not take it apart to service