Rear wheel bearings

[BSA_54A10]

And SEAL is the wrong word
It is a dust cover no more no less.
It does not & never can or will make a seal.

Currently I pretend to fix mowers
I get ride ons in that are less than a year old with stuffed spindle bearings because the owners use the wash out port when the mower is hot and when it gets cold with water on it the water gets sucked into the bearing.
Pulled way too many apart to fund the races full of water & rusted.

[Peter in Aus]

There is a formula to work out how much grease should be applied to a bearing before fitting
A while ago I had to replace the spindle bearings on my milling machine
These are high precision matched pair's you have to align marks on the inner and outer races when fitting them
They cost the best part of €500 for the pair trade price
A special grease cost €25 for a little tube
I cannot remember exactly the quantity but the required amount of grease was tiny 

John

The rule of thumb is 1/3 full of grease, most of the “so called” seal bearings I have looked at are way short of that more like about 5% full.
And as Trev said they are only dust covers.

[chaterlea25]

Hi All,
Trevor,
I had not come across that problem with the lawnmower deck bearings, but could see it happening especially in warmer climates.
When I replaced the deck on my ride on I had it blasted and zinc dipped before fitting it
Th grass can be very wet over here 

There are "sealed" bearings and there are corrosion "proof" bearings like these
http://www.skf.com/group/industry-solutions/food-and-beverage/processing-stages/post-processing-and-packaging/skf-stainless-steel-deep-groove-ball-bearings-with-solid-oil.html

There are also different materials used for shields/ seals where the bearings are exposed to water "spalshes" etc
The seals fitted to normal bearings are designed to keep the grease inside not so much contaminants out

If you fancy there's an easy dodge to add grease to a sealed bearing without removing the seals
cut a hole in a piece of rubber gasketing say 1/8th thick,  smaller than the outer race  but larger than the OD of the inner, place this on a flat surface and the bearing on top, fill the inner bore and the hole in the rubber with grease
Push a tight fitting cork or tight fitting dowel/ spindle into the bearing bore while holding the outer race tightly down onto the rubber gasketing
Take it easy or you can easily pop the topmost seal out as the bearing will be full of grease 

John

[Peter in Aus]

If you fancy there's an easy dodge to add grease to a sealed bearing without removing the seals
cut a hole in a piece of rubber gasketing say 1/8th thick,  smaller than the outer race  but larger than the OD of the inner, place this on a flat surface and the bearing on top, fill the inner bore and the hole in the rubber with grease
Push a tight fitting cork or tight fitting dowel/ spindle into the bearing bore while holding the outer race tightly down onto the rubber gasketing
Take it easy or you can easily pop the topmost seal out as the bearing will be full of grease 

John

That's a good one John I will try that
Peter

[kiwipom]

Hi guys, sorry John couldn’t work that method out, cheers

[Rex]

Beyond me too, but then so is the idea of adding grease to a "sealed for life" bearing...

[BSA_54A10]

Hi guys, sorry John couldn’t work that method out, cheers

The outer race is thinner than the inner race on a standard ball bearing 
When put on the gasket material the inner will be clear of the table but the outer makes a seal against the gasket material.
The axle hole is filled with grease then a plunger ( the cork ) is pushed into the axle hole pushes the grease down and around the seal then past the lip & fills the bearing, compressing the air inside the bearing which will cause the top seal to distort and pop out if you over do it.

Doing it this way does not damage the lip on on the seal as picking it out can easily do.

[BSA_54A10]

Hi All,
Trevor,
I had not come across that problem with the lawnmower deck bearings, but could see it happening especially in warmer climates.

When I replaced the deck on my ride on I had it blasted and zinc dipped before fitting it
Th grass can be very wet over here 
John

John,\
It is the same mechanism that draws water into a hot chain that is left to cool down while still wet.
Decks should be blown off with compressed air.
Air actually shifts grass, even wet grass a lot better than water.
he water sits on top of the upper bearing and fills up the cup on the lower bearing then gets sucked in as the bearing cools.

Good idea with the zinc but keep an eye on it as wet grass is quite acidic.
When I get paid to do a deck it gets 2 coats of POR 15 chassis coat then a top coat.
They never ever rust after that, even if the deck cracks.