|   Why does my free-hub keep loosening up? | MD
Oct 11, 2001 3:38 PM | | I have an XT (FH-M750) rear hub whose free-hub bolt keeps coming loose. This has happened in the last three rides in a row. After the first event, I tore down the hub and cleaned, greased, and applied blue Locktite to the free-hub's bolt. I then torqued this bolt to ~22 in.lbs.(pretty tight). However, the free-hub bolt keeps coming loose after subsequent rides. What the heck is going on here? Can somebody please help me? |
| Did you really mean ~22 in./lbs.? | tl1
Oct 12, 2001 5:21 AM | | That's obviously way low if so and is not very tight.
Shimano says 87-217 in./lbs.
http://www.parktool.com/repair_help/torque.shtml |
| No, sorry. I really meant to say ~22ft.lbs. | MD
Oct 12, 2001 5:51 AM | | Sorry about that. Yes, 22 in.lbs is hardly tight at all, and I definitely meant to express this in ft.lbs. However, even at this relatively high torque, the free-hub bolt keeps loosening up.
I have inspected the splines where the free-hub and the rear hub interface one another, and the 10-toothed aluminum splines on the rear hub are looking a bit elongated (similar to how the spaces in-between a worn out chain ring look). This is probably allowing the free-hub's body to be able to rotate fore and aft ever so slightly, enough so that it allows the bolt to loosen up. What do you think? It looks like my hub may be toast.
Oh by the way, thanks for the info. 87-217 in.lbs. translates to roughly 7-18 ft.lbs., so even though I was torquing the bolt a bit tighter than this it hasn't helped. I'm thinking of using some red Locktite, not only on the bolt, but also on the elongated splines to help fill and snug up the spaces. Hopefully just enough to keep the free-hub's body from slipping forward and back. Again, what do you/others think? |
| Actually, you referred to the incorrect bolt... | MD
Oct 12, 2001 6:11 AM | | No problem though, since you did supply the link to the info, and I greatly appreciate it by the way. However, the bolt you were referring to was the "Hub cone locking nut, 87-217 in.lbs." On Park's torque table, the bolt we're referring to was right below this, and is the one for the "Freehub body, 305-434 in.lbs." That's roughly 25-36 ft.lbs. That's pretty darn tight, and therefore I wasn't tightening it enough (~22 ft.lbs.). I think this and the red Locktite could do the trick. I'm actually worried that such a high torque will actually strip the threads out of the hub though. Oh well, I just hold my breath and go for it.
Again, thanks for the info! |
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