The ball bearings used in the Spridget hubs are "thrust" type bearings. If
you look at a cross section of the races, you would see that there is a lip
on one side only that resists loads put on the balls in that direction.
Loads on the balls in the other direction can push the balls out
of the cage. That's why it is important to install the bearings with the
side marked "Thrust" toward the spacer. The spacer is there to resist
loads on the balls in the "non-thrust" direction, and to keep them from
coming out of the bearing. Shims are used to
compensate for dimensional tolerances from one set of bearings and hubs to
another, to ensure a positive pre-load of the balls in the "thrust"
direction, and to allow lining up the nut with the cotter pin hole at the
proper torque. A given hub/bearing combination may or may not need shims.
The spacer does nothing to strengthen the stub axle. Putting the axle
under a tensile pre-load to prevent it from breaking actually does not make
sense. Loads on the stub axle are primarily shear and bending. Bending
loads put a tensile stress on the bottom surface of the stub axle (and
compressive loads on the top surface). Any
tensile pre-load put on the axle would be added to by the tensile loads
from bending and
would tend to cause the axle to fail sooner.
Now, if you could put the axle under compressive loads, that would help.
Steve Byers
Havelock, NC USA
'73 Midget GAN5UD126009G "OO NINE"
"It is better to remain silent, and be thought a fool
than to speak, and remove all doubt" -- Mark Twain
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From: David Ramsey <dwramsey@worldnet.att.net>
To: Thecarguru@aol.com
Cc: spridgets@Autox.Team.Net
Subject: Re: A question on wheel bearings
Date: Friday, October 30, 1998 12:31 PM
Sorry guys I can't resist, I run tapered cone roller bearings from timken
without the spacer in my hubs. This allows you adjust the pre-load on the
bearings and kicks butt when compared to ball bearings. I thought
everybody knew that, but when I posted it before I found out that my wheels
are going to fall off because the axles are so weak on these cars that they
need the bearing spacer to support them. Was I surprised that this spacer
that gives the ball bearings some kind of pre-load (not really it just
spaces them apart) is the only thing between me and the front wheels on my
car flying off. Last month I hit a pot hole on I-80 east of Reno that
threw my car into the air and had an axle snapped I still would run the
tapered cone roller bearings! I was surprised the whole front of the car
didn't break off. It was so bad that I spilled my beer, dropped my
cel-phone (I was talking to my lawyer), and worst of all I lost the draft
of the "triple trailer" 18 wheeler. OK you can all go back to more
important things on the list now.
Crash
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