Replacing a Hollowtech II bottom bracket.

UndercoverElephant

Hi Chaps,

I'm trying to replace the bottom bracket on the BeOne, it's just too frictionalicious for my taste. I have the correct Hollowtech II tool, but I've come cross a problem when removing the crank bolt. It seems that somehow in the factory, they managed to tighten this bolt an amazing amount (for a plastic bolt), and now I can't get the little bugger out.

This probably explains the friction problem, the bolt is meant as a positioning aid, rather than being really damn tight. Being plastic, it's also starting to thread badly when I try to remove it.

I'm considering just "helping" it to come out using a drill, as I think I need a new one anyway. This leads me to my question. When I look at the crank bolts which I think are correct:

http://www.chainreactioncycles.com/Mode ... delID=5095

It says that they're " Only suitable for XTR, XT and Saint.", does this mean I need something different for Tiagra?

Cheese.

Canny Jock

You might need the M580, which is the last option shown on your link.

d.n.f

What's the difference then? The thread?

I ask as I think I'll be needing a new one of these soon... :oops:

cee

its always worth undoing the pinch bolts at the fat end of the crank arm too....this can release the plastic thingy a bit of slack space so you can undo the rest of it...

Although...last time I did this, I ended up mullering that little plastic thingy getting it out.

UndercoverElephant

Canny Jock wrote:

You might need the M580, which is the last option shown on your link.

Thanks, CJ. I think you're spot on with this one.

UndercoverElephant

cee wrote:

its always worth undoing the pinch bolts at the fat end of the crank arm too....this can release the plastic thingy a bit of slack space so you can undo the rest of it...

Although...last time I did this, I ended up mullering that little plastic thingy getting it out.

Good advice. looking at the tech document on the Shimano site, it appears that the plastic thingy may well be what's holding me back.

davis

Yep, I had exactly this. Undo the pinch bolts completely, give everything a bit of a wiggle, and still the cap was *tight*. Ended up working my way through ever-larger torx/hex bits trying to undo it (it was an aluminium, rather than plastic, cap with an internal hex head, but I've had it happen with the plastic caps too)

You might wish to let the cranks warm up if they're cold in case metal expansion helps you out. Doubt it'd make much difference, but least you leave the bike inside and go do something else for a bit and you won't lose anything

UndercoverElephant

davis wrote:

Yep, I had exactly this. Undo the pinch bolts completely, give everything a bit of a wiggle, and still the cap was *tight*. Ended up working my way through ever-larger torx/hex bits trying to undo it (it was an aluminium, rather than plastic, cap with an internal hex head, but I've had it happen with the plastic caps too)

You might wish to let the cranks warm up if they're cold in case metal expansion helps you out. Doubt it'd make much difference, but least you leave the bike inside and go do something else for a bit and you won't lose anything

You chaps are genii! When I removed the bolts, unhooked the plastic thingy and wiggled the crank-arm a bit, I was finally able to remove the bloody thing. It was so badly stripped though, that I had to use a chisel as a make-shift screwdriver to remove it.

The BB replacement was a piece of pish after all that. The old one was indeed VERY gunked up and frictiony, the new one is lovely. Now all I need is the postie to get his end in gear and deliver the new crank cap - I'm still using the old, stripped one for now. Excellent!