Topic: 2RS or ZZ ?

[Tiek101]

I've read here that the rear bearings for a 750K5 (and others) is: 6304 (2) & 6305 (1).
My question is does it matter if they are 2RS or ZZ?  There are a crap load on Egay but I don't know if one type is better than the other.

...thanks

[scunny]

 




Sizes 6305-6310 Radial Ball Bearings
SKU: 6305-6310

Use the descriptions below to help you find the size bearing you are looking for. Please remember that "2RS" means two rubber seals and "ZZ" means two metal shields.

If you need one of these bearings without 2RS or ZZ, buy the 2RS and remove the seals.

Use the scroll menu at the bottom to choose the part number you want and choose between 2RS and ZZ.

6305(2RS,ZZ)
I.D. 25MM
O.D. 62MM
WIDTH 17MM

6306(2RS,ZZ)
I.D. 30MM
O.D. 72MM
WIDTH 19MM

6307(2RS,ZZ)
I.D. 35MM
O.D. 80MM
WIDTH 21MM

6308(2RS,ZZ)
I.D. 40MM
O.D. 90MM
WIDTH 23MM

6309(2RS,ZZ)
I.D. 45MM
O.D. 100MM
WIDTH 25MM

6310(2RS,ZZ)
I.D. 50MM
O.D. 110MM
WIDTH 27MM

Hope this helps

[Tiek101]

Thanks, it helps as far as what the difference between the two is, but I'm still not sure which one to use.

[scunny]

I have looked thru my 2 manuals and they don't state which ones, but the pictures show bearings with the rubber seals. I don't think it really matters but I'm sure wiser people will chime in.

[crazypj]

RS=Rubber SEALED
ZZ=? but it has two metal SHIELDS.
Go for RS, remove seal from one side only if you need to and leave the other in place as extra protection( fit non sealed side towards each other)
I prefer to use RS but 2 RS are easier to get. I repack bearings before fitting (use synthetic wheel bearing grease.)
PJ

[Tiek101]

Thanks guys, I'll go with the RS.

[bryanj]

Years ago i was told that a rubber seal was a steel seal with a rubber coating, dont know how true it is as i never bothered to pull bearings apart to find oout

[Bodi]

ZZ have a steel shield protecting the cage and balls from large objects. Liquids and fine dust easily get in.
RS is a contact rubber seal. It will keep everything out in normal use. If there's a pressure differential across the bearing then the grease does get forced out the low pressure side but that would be a misuse of the bearing. The seal is not sufficient for underwater use.
I would use 2RS on wheels and not remove the inner seal. The bearing will retain its grease and run smoothly for many years.
The seal does have some friction, for wheel application this is trivial. You will notice it trying to do a static balance on a wheel but a good balancing stand has its own low-friction bearings.