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Shielded vs Unshielded Bearings

catterar
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Shielded vs Unshielded Bearings

Post by catterar » Mon Sep 05, 2016 10:37 am

I bought 2 rear wheel bearings part number 96100-63030 on flea-bay. When I received them one was shielded and one was unshielded. Both had the same data stamped on the outer race. I wanted to ride the bike to a show so I installed these bearings the unshielded bearing on the brake side and the shielded one on the sprocket side.
I have put about 100 miles on the bike since installing these bearings. What issues will result from using an unshielded bearing on the brake side of the rear wheel? Should I source another shielded bearing to replace the unshielded bearing?

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G-Man
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Post by G-Man » Mon Sep 05, 2016 10:41 am

As the rear brake would be most affected by any grease leaking out I would have put them the other way around.

The shield is there to keep grease in and dirt out. Did you put any grease on the inside between the two bearings? If not the bearing with the single shield may run dry.

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
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catterar
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Bearings

Post by catterar » Mon Sep 05, 2016 11:37 am

Thanks G-Man,
Since only one side of the original bearings had a shield, and these were inside the hub, I choose to put the bearing with no shield on the brake side since that side has an oil seal on the outside. My thought was that any grease that was thrown out would be trapped inside the hub along with the rear wheel distance collar and that the oil seal would prevent any grease from reaching the brake drum and shoe.

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G-Man
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Re: Bearings

Post by G-Man » Mon Sep 05, 2016 3:23 pm

Catterar

Sorry, forgot about the oil seal. You should be fine. Originally, though here would have been grease packed between the two bearings.

G
catterar wrote:Thanks G-Man,
Since only one side of the original bearings had a shield, and these were inside the hub, I choose to put the bearing with no shield on the brake side since that side has an oil seal on the outside. My thought was that any grease that was thrown out would be trapped inside the hub along with the rear wheel distance collar and that the oil seal would prevent any grease from reaching the brake drum and shoe.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

catterar
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Location: Angier, NC

Grease

Post by catterar » Mon Sep 05, 2016 4:58 pm

Do you mean the whole inside of the hub around the axle would have been packed with grease?
If so I can pull the wheel and do that.
Thanks,
Bob

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Tim Allman
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Post by Tim Allman » Mon Sep 05, 2016 5:46 pm

When I was an apprentice auto mechanic about 1970 I used to replace wheel bearings (tapered bearings on the front wheels with drum brakes) often. I was told to pack the bearings with grease which makes sense but also to pack the inside of the hub with grease up to the level of the outer bearing race. I never understood the point of this because it seemed that the centrifugal force would tend to strip the bearing of its grease and the grease in the hub would never flow to the bearing because it would be uphill so to speak. The grease in the hub seemed to me to be wasted. This was confirmed by the lack of grease movement when the hub was disassembled later.

On my own car I did not pack the hub and never had a problem. Similarly with my motorcycles. The grease stayed in the bearing and none ended up in the hub as one might have expected. I think the truth is that the rotational speed of the wheel is just not high enough to strip the bearing of its grease.

Because the open bearings that were standard equipment on the CB77 required repacking periodically due to contamination of the grease, I finally ended up using fully sealed bearings and never had a problem. The sealed bearings would just fail gently and could be replaced as needed.

My suggestion is to go to a place that sells bearings and get another 6304Z (half sealed) bearing, pack it with grease and install it. (This is a standard industrial bearing.)

G-Man, if you have experience that contradicts mine, I'd love to hear it because the question 'to pack the hub or not to pack the hub' (apologies to Shakespeare) has been stuck in my head for more than a few years.

Tim

jgger
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Post by jgger » Mon Sep 05, 2016 7:40 pm

I too pack the hubs on my vehicles. The reason for me is that as the wheel becomes heated the extra grease can migrate into the bearings. I have noticed that on my truck the "extra" grease is always spread evenly inside the hub and has a smooth surface (if that makes sense) when I take them apart. Long trips and hot weather would come into play here. Also on a car/truck you can see where some of the "melted" grease seeps out of the bearing cap.

But that's just me.......grease is much cheaper than parts.

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