Cranks on too tight...?

[DrSquirrel]

Firstly, I have a FSA Gossamer (triple) with 105 (external) BB.

BB was creaking a bit, so I stripped it down (first time for me), cleaned it up (bit of water got in), greased it all up and put it back in - no problems and no cross threading. I put the drive side crank/shaft through - little tight so enticed it in with a block of wood, and put the opposing crank arm on... the drive side wasn't fully on so I used the "dust cap" to pull the cranks together.

I have no idea what it is, so I will call it "dust cap", its the same as the smallest item in this pic.

Firstly - it worked, I was using a small ratchet and it didn't take much effort. BUT - I stripped the head, what is worse the crank arms don't seem to be turning so freely by hand. When riding its not so bad, but the idea that the drag is there troubles me.



Can I overtighten the "dust cap"? Any ideas on how to remove it?

 

[henshaw11]

Dunno of these are the exact instructions, but they're probably pretty similar:

http://www.fullspeed...Crankset_v5.pdf

(from http://www.fullspeed.../CRANKSETS-ROAD)

I suspect the (stripped) cap - is as much to preload the bearings, thereafter you tighten up the pinch bolt(s) to actually hold the cranks on - a bit like an aheadset (topcap then stem bolts). So it could be possible you've put too much preload on the bearings, and that's why they're binding.

Is there enough of the hex recess further in - eg could you use an extension bar with hex adaptor and undo it by approaching from the other end of the axle, on the inside (mebbe 3/8 or 1/4 fittings).

Alternatively - if you've *very* careful with a needle file you could open up the existing hex to the next size up, and it might even remain useable.

 

[DrSquirrel]

Preload Bolt - that's the name.

The bolt is pretty soft, hence why it stripped - it does say it only needs very low torque on it as well (not that I have a torque wrench that goes below 50Nm). It's not very deep so I suspect going in reverse isn't going to help.

I could probably hammer in a slightly larger hex nut to undo it...

Also looking online it looks as if they aren't too expensive, not sure if I have the correct thing yet - I don't understand why they come in pairs (I can't see them being for a cartridge bb) - http://cgi.ebay.co.uk/FSA-15mm-Bott...sure_cycling_bikeparts_SR&hash=item53e023bf83

:/

 

[henshaw11]

Hammering another allen key in there may well work, but if it's that soft you might just deform the ally that's there and wind up forcing any available material further in, scuppering yourself further (hence the needle file suggestion).

You might even be able to drill a couple of small holes for a (springy) peg spanner - if you have one - but if it's relatively tight already then the new holes might strip too if there's not much depth of material.

The ebay link - pretty sure those are different. They're steel for a start, and they look like they're the same bolts you'd use in the older ISIS style BBs -which would explain the pairs (also they're probably M15, the pdf for the cranks - if it's the correct one- lists is a M18 or M12)

Ah - have a look here, there's a few listed (including the ISIS versions) - amongst that lot it looks like there's a version for Gossamers - does it look likely ? You could ping CRC a mail to check for the right part...

http://www.chainreac...spx?ModelID=679

 

[gbb]

Certainly lower down the FSA order with Omega cranks, you tighten the preload bolt just enough (if you're not using a torque wrench) to allow the cranks to spin freely with no play, then tighten the 2 pinch bolts (grub screws either side of the non drive crank).
Tightening these will then clamp the preload bolt in the position youve tightened it to.
Beware overtightening the preload bolt, you'll put too much side load on the BB bearings...and cream cracker them.

 

[DrSquirrel]

I guess I should release the pinch bolts a bit before I try to remove the preload then - I didn't think it would be an issue but I can see the possibility there.

http://www.wiggle.co.uk/fsa-v-drive-lh-crank-bolt/#more Looks what I need @ £2.60 isn't bad. Mine is like the Standard version.


Tried putting a hex bit through the back but the "slightly small one" (due to stripping) wont even engage so im not sure if its actually hexagonal all the way through.


This is my exact crankset for info - http://www.fullspeedahead.com/products/27/Gossamer-Triple-MegaExo

Part (7), is "M18 Preload Bolt x1 or M12 Preload Bolt x1" - certainly ambigious - at least the above link is M18 (or M15).

 

[fossyant]

Smack a larger torx bit in and remove that way. There is a reason lots of hex sockets are very small these days so you don't over torq it.

Could be your hex key was worn, causing the socket to round off.

Never mind, no big deal.

 

[DrSquirrel]

hex key is pretty good condition (and not all that old), my kit has multiples also of bit sizes.

I tried putting a torx bit in too, as the next hex bit up was too big... couldn't get it far enough in - could do with a mallet with more weight behind it than the wooden block, and then tried the larger hex but no go.

I will loosen off the pinch bolts and pull a smaller torx nut to the side whilst turning the crank arm and see how that goes, other than that I will probably attempt to cut a groove in it - unless I can get some bolt extractors before I run out of "I will wait and take my time" time

 

[henshaw11]

Good point re torx bits - I'd forgotten about that (tho' never had to use it).

It might a bit knackered if you didn't get the allen key all the way in - I've certainly knacked one of the miniscule hex bolts on a hope mini master cylinder but slipping with it when not fully engaged. A slot cut with a dremel sorted it tho'
They're now torx - engage better and less likely to slip.

 

[Globalti]

It might be possible to extract it by using a small bolt and some washers and nuts. If you can rig it up to lock the bolt inside the problem threaded sleeve/nut thingy you might be able to wind it out. I've used this method (as suggested by Sheldon Brown) to remove tight fixed BB cups from frames.

 

[DrSquirrel]

The bolt idea came up, but we ended up drilling it out to around 12mm and hammering inside the unit to rotate it - and it came off, took less than 5 minutes.

Loosend off the pinch bolts, and back on - cranks are movely freely now, so certainly preloaded it a bit much.


Thanks for the ideas and all