bearings

piet..The clearance differential arises from different clearances created internally BETWEEN the races in manufacture.

The truth..it is hard to believe..that manufacturing tolerances are soooo good that they can mass produce bearings with less than 2 micron variables accurately, every day.
 
C3 bearings are quite common fitment for wheel bearings. As Piet and Rusty have said, it's all to do with how the bearing fits into its respective  housing. This is an interesting thread and it prompted me to find out a bit more as to why some manufacturers will specifiy C3 and others don't.

I'm told its to do with the quality of the alloy used in production. Italian manufacturers tended to use high quality alloys which have a high rate of expansion. Consequently they often specify very close fitting tolerances clearances for bearing housings and this in turn means they require C3 bearings.
Japanese manufacturers use alloys with a high silicon content which is particularly suited to their die casting processes. These alloys have correspondingly lower rate of expansion and therefore the fit of the retained bearing is more predictable and manufacturers will specify standard clearance bearings knowing that the expansion rate won't create a loose bearing fit.



 
One problem with bearings these days, the major manufactures outsource production to China, Brazil and India. Got some FAG bearings with "Germany" stamped on the steel race and "made in China" on the box.  I hear Timken bearings and components made in Brazil and SKF makes bearings and components in India or China. "SKF India registers 25% increase in Sales and 40% increase in Profit After Tax in Q1 2011  * Highest ever quarterly Sales in excess of Rs 6000 million"



It comes down to quality control. The reputation of the old line European bearing companies may suffer with "made in" not exactly the truth. It may be a problem as some euro import techs are replacing name brand wheel bearings (automotive) under factory spare parts warranty. They just don't seem last as long as they used to.

SKF_Spherical_roller_bearings_22220.jpg.middle.jpg


Hey..it's a C3 bearing!
 
Interesting you use SKF as an example. I bought my new bearings for the steering head, swing arm and wheels from the local SKF outlet. Spoke with the guy at the counter in regard to sourcing bearings from all over the globe. He stated that SKF provide the machinery and the steel for the manufacture and that the quality should be the same no matter which country they are made in.
 
sfcpiet said:
Can't remember finding C3 bearings in any Laverda wheel hub...
Click to expand...
When I did the front wheel bearings in my Zan? Formula I noticed they were C3, Piet.  No idea if they were original, mind.  Parts books says nowt ...

But because I already had 'em, it was standard bearings that went back in ...  ;)

Ciao

Craig
 
Here's a small illustration showing where the clearances are within bearings.  C2=smaller than normal, C3 and higher=greater than normal clearance.

External dimensions are as normal clearance bearings, so press/interference fits should be the same across the range of any particular bearing denomination.

piet
 

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