Hot Bearings

Dave August · 2006-11-22T16:52:06+00:00

I'll try and make a long story short and get to the point...Vari-drive on my clausing came apart on Friday evening :-( Circlip that holds it all together in the pulley sheave was destroyed and the whole assembly came off... In the process of disassembly I realized that the outer bearing was toast and the one in the movable sheave wasn't in the best of shape... So Monday was a trip over to Salinas and the local bearing shop to get a couple of replacments...Reassembly went with out too many problems and I even replaced the old cracked hose and slave cylinder seals (no leaks or creep now)... thats the up side...Down side is that the bearings seem to be getting pretty warm (hot?) after about 10 minutes of running. These are sealed bearings no lube necessary and I *believe* the replacments are correct...Original bearings were Fafnir 205PP replacments are MRC 205SZZ (STEEL/C3ABEC-1/EMO MX) ... FWIW there is no radial load on these is all axial,. they keep the slave cylinder from rotating against all the force that it takes to close the split pully sheave... also not too suprising the bearing out in the open with virtually no heat sink gets a LOT hotter then the one in the movable sheave which acts as a heat sink...any ideas or advice?--.- Dave

Nov 22, 2006 21 Replies

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Gene Kearns 19 years ago

On Wed, 22 Nov 2006 16:52:06 GMT, Dave August penned the following well considered thoughts to the readers of rec.crafts.metalworking:

Thoughts....

The new bearings are sealed (2-sides;SZZ)... and not, as some have suggested, shielded.

The (ABMA) C3 refers to internal clearance. The C3 clearance is looser than the (normal) C2 clearance. If you buy an off-the-shelf bearing, you're probably going to end up with a C3.

And the bearing is manufactured to the ABEC-1 tolerance.

I'd be curious to know if the bearing is actually (still) lubricated!

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REMOVE 19 years ago

You are correct about the seals/shields. MRC elects to use Z to designate seals whereas most mfgs. use it to designate shields. C2 internal clearance is actually tighter than normal. Most mfgs. use no designation or C0 to designate normal with C3 being looser and C2 being tighter. Some mfgs. use EM to designate electric motor quality which will include C3 internal clearance or will designate it as C3. If it doesn't have one or the other or some other designation (C4 for example) you most likely have a normal clearance.

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