Bearings are fundamental towards keeping
your car in good condition. Stuck or seized bearings can
cause the transmission to suffer a premature death so its
well worth looking after the bearings. Bearings or Bushings
? The first thing you should ask yourself is whether the car
has bearings or bushings. A bushing is simply a piece of
metal/plastic with a hole cut in it that allows a shaft to
spin in it.
A bearing is a bit more complicated in that it the shaft
rotates on enclosed balls. There is a smaller contact patch
when a bearing is used therefore there is less friction.
If you have bushings, you would be wise to ditch them quick
and get some bearings! You will have more run time, speed
and less wear with bearings.
Sealed Or Shielded Bearings
A shielded bearing has a side cover made of metal and is
fixed in place by a metal retaining "C" Clip. The C clip
holds the bearing against the outer race. The shield touches
the outer race but not the inner race. So there is no
bearing friction introduced.
Because there is a small gap between the inner race and the
shield, this allows dirt and grit to contaminate the bearing
(make it gritty). So shielded bearings generally require
high maintenance.
A sealed bearing has a side cover made of metal coated in
rubber (or teflon etc). No C clip is required as the seal is
pressed and fits snuggly between the outer and inner races.
The seal touches both the inner and outer races so there is
a bit of friction.
However because there are no gaps in the bearing, the
likelihood of grit and grime contaminating the bearing are
minimal.
Removing Shields
To remove a shielded bearing, jab a pin into the gap near
the edge of the bearing and prise the C clip out towards the
center of the bearing. Once the C clip is removed, you can
just tap the bearing and the shield should just pop out.
To
rebuild the bearing, simply put the shield back into place,
and insert the C clip, you'll hear it click as it goes back
into place.
Removing Seals
To remove a seal from a sealed bearing is very simple. Just
get hold of a pin and push it the edge of the seal (near the
outer or inner race) and pry it out.
To replace simply push the seal back in.
Maintenance
First things first, if your bearing is contaminated you need
to flush all the crap out. Remove the shields or seals and
spray with engine degreaser (you could use motor spray too).
Then let the bearings dry out (this is very important).
Once dry, you have two options, you can either refill the
bearing with grease (as recommended by SKF, Timken etc) or
oil. If you use grease, the bearing needn't be serviced as
frequently and the wear on the bearing is not that much.
Grease does however cause the bearing to have a bit more
friction than oil.
If you use oil, there is less rolling friction in the
bearing. However while the bearing is spinning there is
hardly any lubricant near the inner race so you will trash
the bearing much quicker. Do not use very thin oil (this
will leak out) or petroleum based lubricant such as WD-40,
this will evaporate! Instead use a synthetic oil such as 3
in 1 or triflo (royal oil in some markets).
