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Hello,
Having some trouble where my cranks refuse to tighten down. Setup is Shimano XT threaded BB on a 73mm BB shell. One spacer on drive side as per instructions.
The crank bolt feels like it is bottoming out but then I have 1-2mm free side to side play (I can push the chainring in and pull it out if that makes sense). Took the cranks apart and have the two black and one red spacer on the drive side (One looked a bit worn so I replaced it, helped slightly but not really). On the non drive side I have the elastomer preload thing.
Any thoughts? Running out of ideas!
Cheers
Are you not running too many spacers? Is it only one spacer on a 73mm shell?
Sorry, to clear up. I'm running one BB spacer.
The other spacers are the small ones that fit on the spindle to adjust chainline. So I need two and the red thing, see here
(3a, 3b and 9)
Are you tightening the bolt up to the incredibly high torque setting specified?
Edit: 61Nm / 45 ft-lbs - car wheel nut tight. Almost impossible to achieve with a standard sized Allen key.
Oh, and have you greased the splines ?
Sounds like your BB shell is less than 73mm...
if its bottoming out on the crank bolt and there is still side to side play, you need to either add more Raceface axle spacers or (after you've measured the BB shell) add another spacer to the BB to move the BB shell out, suggest that you do that on the non drive side to avoid messing the chainline.
BB spacers are 2mm, so if you have 2mm of side to side play, start there rather than packing out the axle with the axle spacers. just make sure it still bottoms out with no play rather than not bottoming out with no play. might take a bit of playing around to get the right preload by adding or subtracting the axle spacers from there, but you'll get there
Have you fitted these cranks to this bike before? If so what's changed?
It can be a bit of trial and error to get these to be just right - if you're happy it's bottoming out then I'd get hold of another 1mm spacer or two and add those in until it's right. If the shell has been "enthusiastically" faced then you could easily end up with an extra mm to take up in slack.
Cheers all. I'll clarify a few things:
-Im using a huge allen key to do it up, relatively sure it's tight enough.
-Splines are greased.
-I've now measured the bb width. On one ruler I get 73mm, on one I get 71mm. I don't have any callipers to hand.
-I've added another BB spacer on the NDS. Done it up tight and now there is no play. There does seem to be a bit more resistance though. If I spin the cranks (no chain) then they'll go for ~1 rev before stopping. It's not a huge amount of resistance to feel but do you think i'll be overloading the bearings? I'm happy to leave it like this if it won't cause the BB to fail prematurely.
-The cranks were on a different frame with a PF BB. They've been on this one for ~2months but i'm prepared to accept that i'm a wally and just didn't notice the play until now.
Maybe try taking out one of the axle spacers and see if it spins freely without any side to side play. sounds like its on the right track and your BB is a bit narrower than spec or its been faced a lot.
Oh, and the big allen key will be fine, just crank it down till it bottoms out and you are done