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Old 11-18-09, 11:03 PM   #1
oilman_15106
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Shimano 7801 hub issue

This should be a piece of cake but I am stumped. Maybe someone can shed some light on what I am doing wrong.

At 2000 miles thought it was time to regrease the bearings and check things out. Downloaded the diagrams and everything looks pretty simple. Disassemble, clean, inspect, regrease and put the rear wheel back together. Now here is the issue:

Tighten the lock nuts on the axle until it seems to spin ok with no play. When I put the wheel back in the bike frame and clamp down the skewer the hub is loose? If I tighten the lock nuts down a bit more and remount the wheel it is too tight and I am sure some damage will happen if ridden?

I am 100% sure everything has been put back in place just as it came out of the thing at the start. Any ideas and thanks in advance as always.
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Old 11-18-09, 11:28 PM   #2
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My guess is that what feels like a perfectly adjusted hubs in your hand is actually an ever so slightly lose one. once the wheel is installed the play that is in the hub is more obvious because holding the rim and shaking gives you much more leverage than simply trying to test the axle between your fingers.

Generally when adjusting a QR hub, installing will actually tighten it a bit. I think this is because it squeezes in that tiny bit a space of the threads that makes threading possible. But that theory may be really off the mark.

I would try micro adjusting the tightness of the cone, checking it at every 5 degrees or so. Find the spot where it is actually too tight to spin smoothly with your fingers and ten back off ever so slightly.

Also, it is very important to tighten the cone and locknut against each other. Otherwise the hub will become unadjusted very quickly.

If the hub has been damaged or worn from use, there may be no perfect adjustment. look for pitting, or dimples in the cone, the hub itself, and the bearings. if that is the case you can replace the easier to replace parts( ie, cones and bearings) replace the whole hub/wheel, or ride an imperfect wheel. It will probably be frowned upon here, but i would say that if you decided to ride it damaged, go for over tightening ever so slightly. It will further the damage and be a short term solution, but it beats a lose hub.
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Old 11-19-09, 12:03 PM   #3
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Originally Posted by sweatforfun View Post
My guess is that what feels like a perfectly adjusted hubs in your hand is actually an ever so slightly lose one. once the wheel is installed the play that is in the hub is more obvious because holding the rim and shaking gives you much more leverage than simply trying to test the axle between your fingers.

Generally when adjusting a QR hub, installing will actually tighten it a bit. I think this is because it squeezes in that tiny bit a space of the threads that makes threading possible. But that theory may be really off the mark.

I would try micro adjusting the tightness of the cone, checking it at every 5 degrees or so. Find the spot where it is actually too tight to spin smoothly with your fingers and ten back off ever so slightly.

Also, it is very important to tighten the cone and locknut against each other. Otherwise the hub will become unadjusted very quickly.

If the hub has been damaged or worn from use, there may be no perfect adjustment. look for pitting, or dimples in the cone, the hub itself, and the bearings. if that is the case you can replace the easier to replace parts( ie, cones and bearings) replace the whole hub/wheel, or ride an imperfect wheel. It will probably be frowned upon here, but i would say that if you decided to ride it damaged, go for over tightening ever so slightly. It will further the damage and be a short term solution, but it beats a lose hub.
Thanks for the input. The hub surfaces and bearings look brand new. And I am tightening per the procedure you outlined above. In retrospect I was too quick to think the hubs needed serviced as nothing was really wrong with them. Will keep playing with it to see if I can get the sweet spot correct.
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Old 11-20-09, 10:43 AM   #4
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something else, especially if the wheel is new to the bike, make sure that the area of the axle that remains exposed and sits in the frames dropouts are not wider than the dropouts themselves. if they are, the QR wont actually clamp to anything other than the axle itself, when it should be putting pressure on the dropouts. this can cause the wheel to fall out while riding. If the axle is too wide you can file or grind it down to the appropriate length for the bike.
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Old 11-20-09, 10:54 AM   #5
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With the biger diameter axle there should be no play in the bearing adjustment. It does not compress.
Make sure that the seal inside the drive side is facing the correct way.
I have worked on friends wheels with that type of hub and found that the seal orientation is important.
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Old 11-20-09, 11:08 AM   #6
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Did you happen to remove the seal on the drive side inside the freehub? If so, that could be throwing off the adjustment. The seal is a bear to get back in to exactly the right position and could create drag which would make you think you've overtightened the hub. The Shimano instructions say not to dissassemble the seal, which can be confusing. It should say to not remove or disturb the seal in any way. I learned the hard way.
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Old 11-20-09, 09:37 PM   #7
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The seal in question is part no. 13. http://techdocs.shimano.com/media/te...9830608916.pdf
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