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RS81 front hub caps

6K views 11 replies 6 participants last post by  wim 
#1 · (Edited)
My friend has a brand new RS81 c24 front wheel, which is a Wh-6800 hub.

The 2 hub caps are not identical:

  1. one cap has tabs the clips on the hub, so it turns with the wheel.
  2. other cap has no tabs and fits very tightly on the hub nut so it doesn't turn with the wheel. As the wheel turns, we can hear friction noise

Is this normal? On the Rs80 front hub, both caps would be snapped in and turn with the wheel.
 
#2 · (Edited)
does anyone have RS81 wheels or wh-6800 hubs? The hubs are the same, ultegra

I found this picture that shows a gap between the hub and the dust cap. As I mentionned, the other side of the hub is different.

On my friend's wheel, there's no gap but there's clearly one on the first picture I posted. Maybe the axle is misaligned or it's missing a spacer? The axle has 2 different diameters on its end, the visible part on the picture 1 is not as wide as the part this is hidden by the cover. My guess is that when pushing on the cap, that wider diameter part of the axle should prevent it from going too close to the hub.
 
#6 ·
this is my friend's wheel. I asked him last month and he had forgotten about this issue entirely!
Not sure what he ended up doing but I guess he adjusted the spacing of the cover so that it no longer rubs. I know that it wants to snap back into place, so he either filed it a bit to make it thinner or he used some sort of spacer to prevent it from going to close and rub.
 
#9 ·
I have a fix for you in case you still need it. I just bought a WH-6800 wheelset, and the front wheel had the same exact problem. The dust cap was rubbing on both the outside and inside of the hub shell because it wasn't properly set at the factory.

Luckily, there is an easy fix:

1. Pop out the front axle assembly. Be careful not to disturb the bearings when you pull out the axle. If there is enough grease, they'll stay in place.

2. Turn the axle assembly so that the left side is facing up and the side with the cone and dust cap is resting flush on your work bench (vertically).

3. Take a large adjustable/Cresent wrench and adjust it so that it fits over the dust cap and comes close to touching the cone (but not quite). The Crescent wrench will now be perpendicular to your axle assembly.

4. Gently, but firmly, tap the top of the adjustable wrench with a hammer. You will see the dust cap "settle in." It doesn't have to move very far--maybe only a millimeter or less.

5. Reassemble hub and set the bearing preload as you wish.

For me, this totally removed any extra friction from the dust cap, and there is now a ~1mm gap between the dust cap and the hub shell, where before it was rubbing quite a bit.

The best thing about this fix is that it doesn't require you to file anything or add spacers. Trust me, it will work!
 
#10 · (Edited)
...this totally removed any extra friction from the dust cap, and there is now a ~1mm gap between the dust cap and the hub shell, where before it was rubbing quite a bit.
Nothing wrong with removing friction. But now with that ~1 mm gap, the dust cap no longer functions as a seal, possibly allowing water and grime to get into the hub bearing. If the friction you removed was significant, it may be worth the trade-off, especially if you repack your bearings regularly anyway.

Doing nothing may have allowed the problem to go away. The friction between the cap and the hub probably could have worn away just enough material to make an effective and silent seal after a while. Until this happens, a bit of lubricant between the seal and the hub might have eliminated the noise.
 
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