Author Topic: Axle Bearings  (Read 516 times)

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Offline n49racer

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Axle Bearings
« on: May 02, 2019, 02:25:26 PM »
This has probably been mentioned but here goes. I use double sealed axle bearings in the 9" in my RMR. I had to take an axle out for something else and the bearing felt rough. The bearings had been in the car for 4 years. Just for a hoot I cut one open. The salt had gotten to it. My message is; just because things are "sealed" it doesn't mean squat on a salt car. Both bearings were the same. Now I will check my axle bearings every year.


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Offline TheBaron

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Re: Axle Bearings
« Reply #1 on: May 02, 2019, 06:47:52 PM »
Good point well said...

The bearings get warm when running and the buildup air pressure will leak past the seals ,,,then, when they cool down, a negative pressure is in the hub which draws salt ladden moisture into the bearings.....

Boat trailer bearings really do this when they are hot from the highway speeds and then back into the water before having a chance to cool down..

Robert "Smitty" Smith

Offline wobblywalrus

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Re: Axle Bearings
« Reply #2 on: May 03, 2019, 09:13:32 AM »
The outsides of the sealed bearings and the axles are coated with marine approved boat trailer wheel bearing grease during the annual pre-race servicing.  This grease coating seals everything so water does not get in the bearings.  This is all that is needed on the Triumph salt flats race bike.

The Yamaha dirt bike is used for winter racing in Oregon and Washington.  The hubs are under water a lot.  More drastic measures are needed.  The inner seals on the bearings are removed.  The bearings are reinstalled.  The hub is filled with the boat trailer bearing grease.  It oozes out of the hubs under pressure between the inner lips of the outer bearing seals.  The grease is gently forced into the hubs until the grease oozing out does not have the milky discoloration that indicates water contamination.

Some applications need this.  A virgin (very sharp) drill bit with the pointy end coated with grease is used to drill a small hole in the bearing seal.  The grease captures the drilling chips.  A hypodermic needle on the grease gun is used to squirt some fresh grease into the bearing.  The needle is removed and the hole is plugged with silicone seal.

Sometimes a "Bearing Buddy" can be installed on the hub.  That allows there to be positive pressure inside the hub so water does not get in.

Rockwell American makes axle spindles that have grease passages so the old grease can be forced out and be replaced with new grease during a service - with no need to remove the wheel from the axle.