When to grease bearings

[InSaneFisherMan]

I was surprised that the manual on my bearing hubs stated to grease before towing and after launch, every time.

It has some information on water intrusion and grease leakage at seals.

I have attached the file for informational purposes.

 

[LDUBS]

Huh, I'm way over my head here but wonder if the bearing protectors discussed at the end of you link would address your concern. Seems they provide positive pressure similar to a Bearing Buddy.

My trailer uses Knott sealed hubs which cannot be serviced. The trailer mfg says they have had good experienced with them, but I guess I would be more comfortable with traditional hub/bearing/bearing buddy set-up. Just so I know it is maintained I guess and I think sourcing parts might be easier too.

 

[MrGiggles]

I do it 5-6 times a year at most. Just normal greased bearings with bearing buddies.

 

[KMixson]

The reason it states to grease every time is because when you drive to the landing the bearings can heat up especially if drive a long distance. Then when you back the warm bearings into the cold water they can suck in water through the grease seal. I think every time is a little overkill but that is me.

 

[maintenanceguy]

The bearing manufacturer SKS says that .002% water in oil can reduce bearing life by nearly 50%. Six percent water can reduce bearing life by 83%. Pumping grease into a bearing pushes out water.

If you're near the coast and launch in salt water, rolling elements can rust in hours. Once there are surface imperfections on the races or rolling elements, wear progresses quickly.

 

[Rumblejohn]

Dexter hubs should be greased before and after every launch if you submerge the hub when you launch.
In my case, I can get by with longer intervals because I don't have to have my hubs under water when launching or loading. Bearings are original on my trailer and it's 9yrs old. My son has a 24ft bay boat, launches in salt water. He also has Dexter hubs on his trailer, but the tops of his trailer tires go underwater when launches. He replaces his bearings and spindles, every third launch

John

 

[CedarRiverScooter]

Use marine grease, it can handle more moisture. As LDubbs said, bearing buddies keep pressure on the grease so it doesn't suck in water. Plus they have zerks. I only grease a couple times a year, which is less than 1/10 launches.

 

[JL8Jeff]

If you have bearing buddies, be careful not to over grease or it could push out the seal. Adding grease will help push out any water that might have gotten pulled in. I always wait a while when I get to the ramp to let the bearings cool down some before backing the trailer in. I also disconnect the lights to reduce the chance of a hot bulb burning out in cold water but that's just me. I think I greased my hubs once or twice in the last 6 years but I don't tow a lot once the boat is in the water for the season. The 2nd boat I had got trailered every time and I greased them a lot more often.