Seal or bearing?

[GTRS Fiero]

Where the harmonic balancer goes through the timing cover, there is a seal.  This means that the harmonic balancer turns against that seal, eventually wearing a groove in the balancer, and wearing the seal out.  Why wasn't there a sealed bearing used, in place of the seal?

[Fierofool]

Generally, a bearing isn't used where there's a lot of vibration.  The crankshaft is supported by bearings throughout it's length, with one being just behind the timing cover.  Putting a roller bearing in the timing cover would eventually beat the bearing or the timing cover apart.  Probably the timing cover since it's the softer of the two.  There is also a small amount of crankshaft float from front to back and this wouldn't work with a bearing due to the tight tolerances of the two races. 

The seal is flexible and deflects as the crankshaft vibrates, but still maintains contact with the crankshaft. 

[The Art Doctor]

On the cars I own the backside of the balancer is not in contact with the crank seal at the timing cover, there is a gap.  Is this a Fiero thing?

[Raydar]

On the cars I own the backside of the balancer is not in contact with the crank seal at the timing cover, there is a gap.  Is this a Fiero thing?

That's pretty normal. The tubular sleeve that slides over the crank nose is the surface that the rubber seal rides on.
There is usually a surface (ridge?) inside of that sleeve, that butts up against the end of the crank nose, that stops the balancer from sliding on any further.
Either that, or the inside end of the sleeve will butt up against the front surface of the crank main bearing.

[GTRS Fiero]

Thanks for the info.  I'm not sure how the other bearings work on the crank, for the reasons stated here.

[scottb]

Crank bearings are journal bearings, not roller bearings. To see an interesting bearing, look up a kingsbury thrust bearing.