New BB question

[Shut Up Legs]

The BB I just replaced yesterday, a Shimano SM-BB5700, appears to allow the axle to wobble just a little bit. I was wondering if this was normal, and I just hadn't noticed it before, due to letting other people replace the BBs? I tightened up the star nut on the left crank finger-tight, then tightened up the 2 bolts on the left crank. I also ensured that the left crank was as close as possible to the BB when I did this. But still I can make the axle wobble slightly when I grip the left crank firmly and move it with my hand. So is this normal? I'm guessing that there must always be a tiny bit of clearance between the axle and the inner BB rings, otherwise I'd never get the axle to go through them, so is this the source of the wobble?

 

[smokeysmoo]

The BB I just replaced yesterday, a Shimano SM-BB5700, appears to allow the axle to wobble just a little bit, is this normal? ?

No, there shouldn't be any noticeable play.

I presume it's Hollowtech II by your description of the 'star nut'? If so then this is in fact a pre-load cap and needs to be tightened just enough to remove any play. Too much and you will cause premature wear to the bearings, too little and you will still have access play.

The two bolts on the left crank are simply pinch bolts to hold the arm onto the axle, so when it comes to play it's all about the pre-load.

The correct tool is one of THESE, but if you don't have this you can use a 20p, (oops you're in Oz aren't you, possibly a 50 cent coin, although that may be a bit big?), and some pliers. Keep nipping it a bit then feeling for play by waggling the drive side crank arm, once no play can be felt then re-fit the non-drive side.

 

[Shut Up Legs]

I just tightened up the star nut (or pre-load cap*) only enough to remove any axle movement. I even did it before reading your post, but appreciate it nonetheless . The tool I have, which I quite like as it's easy to use, is one of these: http://www.parktool.com/product/bottom-bracket-tool-bbt-9 and it was part of this: http://www.chainreactioncycles.com/Models.aspx?ModelID=17700, the best tool kit I ever bought. I've been happily working my way through the tools in it.

* aka thingamijig, whatsit, doohickey