Final Driven Flange bearings: I'm so confused.......

dduelin

Tune my heart to sing Thy grace
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Joined
Feb 11, 2006
Messages
9,641
Location
Jacksonville
Bike
GL1800 R1200RT NC700
2024 Miles
006739
STOC #
6651
Discussion of these bearings has cooled off in the last few years. The last reported low mile failure was on a 2004 model. Like early bike thermostats I wonder if 2003-3004 perhaps 2005 (not my 05, the OEMs went close to 100,000 miles) bikes had suspect bearings that were much improved in quality in subsequent model years.
 
Joined
Aug 9, 2010
Messages
292
Location
Vernon BC Canada
Bike
09 ST1300
I don't see any mention of rear axle torque spec here. I wonder if anyone who has experienced early bearing failure has ever had the rear axle nut over-torqued and thus squashing the spacer collar in the wheel by a couple thou. This would set up undo side loading of the bearing stack-up and will certainly lead to early failure. Would be interesting to measure a few new and used distance collars (the one inside the wheel) for comparison.
 
Joined
May 9, 2014
Messages
129
Location
Minneapolis, mn
Just about to order these when I read your post that SKF doesn't make these. I'm a SKF fan so whats your take on this? https://www.123bearing.com/bearing-6905-2RS-SKF.php


I work with bearings on high speed, high load, proprietary assemblies; we use almost exclusively SKF (occasionally Timken, Lufkin, NSK) and will NOT use a Chinese supplied bearing, no matter how much lower the cost. There are simply too many dimensions to get right and too much cost if a bearing doesn't last. There is a difference in bearing manufacturers.

You mention 6204--the left (disk side of the wheel) rear wheel bearing is a single 6204UU. The flange driven bearings are a pair of 6905RS bearings, mounted side by side, with each bearing's seal positioned to the outside face of the pair of bearings. I mention the bearing numbers only so that a reader of this thread doesn't mix the two.

Regarding the 6905 flange driven bearings: I put Honda-packaged OEM bearings in mine after a set of Honda factory-installed OEM bearings failed at <35,000 miles. (SKF doesn't make 6905 radial ball bearings, or I'd have tried them.) I proactively removed that second OEM set at ~25k miles and they were in good shape (but I tossed them anyway to avoid the temptation to use them longer). I replaced that second set with another Honda OEM set, and that 3rd set is still 'young' and installed.

Regarding the seals, some 6905 bearings are built as "-2RS" and others as "RS" (both sides sealed vs one side sealed). While I believe Honda specifies "RS", folks have used "-2RS" without issue. I think "-2RS" is a bit better (just my opinion). Honda species "RS" with the seals positioned on the outside of each bearing pair (therefore the inner, adjacent faces do not have seals between them)--this allows slighly more space for grease**. The problem is that if one bearing starts to fail and there's no inner seal, debris from within the failing bearing ends up in the still-good bearing--it will fail quicker than if a seal were there to keep the debris out.

**Never fill the entire space within a bearing with grease! Always replace ~1/2 of the bearing airspace with a good wheel bearing grease.

You'll likely hear replies from folks who've successfully used VXB bearings, ceramic bearings, double-wide needle bearings, etc. To each their own. :)

Specifically to your questions:

1. Honda's part number for their 6905RS bearing is 91052-KZ4-J21. Google it and you can find many places to consider buying it from (or to ask your dealer to get for you).

2. Never use moly disulfide paste within bearings. Such is not proper for bearing ball and raceway cooling and lubrication as paste doesn't have the correct properties--the moly paste becomes hardened moly 'cake', the bearing runs dry (runs hot), and has lumpy moly crumbs spinning inside it! Moly disulfide paste is only for parts with very slow relative motion, high-load surfaces like splines. For grease within a bearing, use a good name brand wheel bearing grease (parts stores have several to choose from).

3. No comment.

3. See #2 above! No moly paste in bearings! Only use moly paste on the splines.

Also, when you put the rear wheel back together, put a very light film of the bearing grease on the axle to avoid corrosion and to allow better heat transfer out of the bearings and collars into the shaft (you want to get heat out of the bearings to make them and the grease last longer).

Hope that helps...
 
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