I've seen people say that Bearings run better unsealed, is this true in all cases? Even with contactless seals?

Should I leave my Bearings seal off after cleaning?

I only fish freshwater so salt is not a concern

Drive bearings get grease and should be shielded to retain the grease and prevent contamination.

Spool bearings should get oil, and will perform better unshielded, adding a drop of oil about 1/mo.

I've not been able to convince myself that an unshielded spool bearing runs "better" than a shielded spool bearing, but I do agree access is easier for mid-season re-oiling. I leave the "access" side of the bearing un-shielded and the other side of the bearing shielded. I'm also not a fan of packing a frame bearing with grease, but use heavy 80-90 wt. lower unit oil. Cal's drag grease has worked best for me packed on gears.

I have - 1/4-oz plug to 200'

2-oz spider weight rig to 400'

Spreading grease around the inside of a reel is a really bad idea. Spreading viscous oil is worse.

There’s no need to open shielded bearings to clean or oil them under normal circumstances. If you do frequent cleaning of the bearings, running them open can get slight improvement in free spin but not enough to notice during casting imo. Go ahead and experiment for yourself if you’re so inclined but don’t stress that you’re missing out on anything.

Are we talking about spool bearings? I only remove the shields of spool bearings when they're crunchy, and in many cases, if they are, they're done, and will never be smooth. I did purchase multiple used reels in the past, and for whatever reason, the shielded spool bearings were full of grease, which i wasn't able to disolve in acetone, so i've removed the shields to properly clean them.

As for all internal bearings, there's no reason to ever remove their shields.

The day I took this photo, I cast 3 different 34-mm Daiwa frames, Steez, Zillion, Silver Wolf (improved LW pitch), and swapped bearings in 3 different spools, 1000S SV Boost, Ray's SV, Roro-X, casting 3-g JH (nominal 100' to 135').

On the 1000S in Zillion frame, between stock CRCC, both Roro and KTF/IXA doubles measured 15% distance improvement. The results are posted in the board archive.

I also measured that day, the increased LW pitch on Silver Wolf cost 10% cast distance.

Jun Sonada reported 7% improvement casting 1/4 oz between shielded and unshielded spool bearings.

2 hours ago, Delaware Valley Tackle said:

There’s no need to open shielded bearings to clean or oil them under normal circumstances. If you do frequent cleaning of the bearings, running them open can get slight improvement in free spin but not enough to notice during casting imo. Go ahead and experiment for yourself if you’re so inclined but don’t stress that you’re missing out on anything.

I learned the hard way for the most part to just leave the shields alone on spool bearings. I still have some without them but the few I took off, I did so with the idea that it would increase performance and it pretty much did nothing. I recall dunking one of those reels in some muddy water and casting that reel was problematic until I was able to clean it again. On the other hand, I have purchased spool bearings that came without the shields and they have been great so far but a marginal upgrade from the original on some reels.

Shields are not seals - they let the muddy water in. What they don't do is let the dried mud out.

Next drop of oil in unshielded bearing with flush it.

All of the main bearing manufacturers ship their products to partners greased. NSK, SKF, GRW, and NMB all ship this way. This isn't for storage purposes, but for the environments they're used. The same bearings used in fishing reels are also used in much more demanding environments like food processing, high speed tooling, dental tools, and analog instrumentation. The reel manufacturers don't degrease spool bearings, they run them as is. Truthfully, these greased spool bearings run satisfactorily for most people, but at some point you may want more out of them. It's much, much easier to remove the grease without the shields, and if the shields are left on, it can take a very long time to get it all out. It sticks to the bearing ribbon pretty good.

Leaving the shields on drive bearings is fine since they aren't involved in casting unless it's a synced level wind. Disengaging level winds are different, so keep the shields on those bearings and the pinion bearings. They're cheap enough to replace if they run a foul.

30 year old spool bearings from a Calcutta 400. Shields removed from one to show the grease. It's pretty dirty. In a fresh bearing the grease will be translucent white.

Same bearings, shields left on and both run in the ultrasonic cleaner in denatured alcohol for 30 minutes. Note the grease left behind in the bearing that was shielded in the above photo. The one that had the shield removed prior to cleaning is spotless. The shields trapped the grease and prevented much of it from coming out.

8 hours ago, redmeansdistortion said:

shielded

8 hours ago, redmeansdistortion said:

shield removed

I just did my first attempts at this. They certainly weren't as thick with grease as these, and I only did about 10-15 minutes in Acetone, but I think they came out clean and fast. Feels raspy now, or is that because they need a second bath?

1 hour ago, Banned User said:

I just did my first attempts at this. They certainly weren't as thick with grease as these, and I only did about 10-15 minutes in Acetone, but I think they came out clean and fast. Feels raspy now, or is that because they need a second bath?

Have you oiled them? Dry bearings are noisy, even stainless.

In my experience, unshielded spool bearings will bring some casting improvements, especially for light lures, light lines, finesse fishing, but the gain is not that significant in real fishing scenario. On the other hand, they will get dirty and noisy more quickly, requiring more frequent cleaning. So, whether the advantages offset the disadvantages, it's totally up to you.