Bottom Bracket .. changing advice required

[Elyob]

Okay, I'm fed up wth the noise coming from by bottom bracket and will change it before the London to
Brighton ...

I'm investigating bottom brackets and how to change. I have a crank puller, and can successfully
remove and refit the cranks. Once the cranks are off, how do you get the bottom bracket out? I've
not tried, as I like to know rather than bodge it.

Also, my investigations suggest that a Kona Muni-Mula has a Shimano UN40 tapered bottom bracket.
Should I consider an improved part? Can I stick in a UN52/3 or UN72/3 ... what difference will
this make?

Thanks

Nick

 

[Tim Woodall]

On Fri, 06 Jun 2003 12:17:52 GMT, elyob <[email protected]> wrote:
> Okay, I'm fed up wth the noise coming from by bottom bracket and will change it before the London
> to Brighton ...
>
> I'm investigating bottom brackets and how to change. I have a crank puller, and can successfully
> remove and refit the cranks. Once the cranks are off, how do you get the bottom bracket out? I've
> not tried, as I like to know rather than bodge it.
>
Step 1. Buy the correct tool. (for the existing BB and the new one) Step 2. Spray WD40 liberally
over the old BB. Step 3. Get up early the next morning. Step 4. Check, check and recheck which way
you need to turn the damn thing Step 5. Remove the BB using GREAT FORCE. Step 6. It's now lunchtime.
Go out to the pub for a snack and celebration. Step 7. Liberally smear anti-seize lubricants over
the new BB Step 8. Insert the new BB making sure you don't cross thread it. Step 9. Tighten using a
lot of force Step 10. Enjoy.

(The BB I removed had plastic end caps at both ends and I had to resort to a stanley knife
and hacksaw and someone here actually had the temerity to state that plastic doesn't seize up
in the BB!)

Regards,

Tim.

--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

 

[Elyob]

"Tim Woodall" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 06 Jun 2003 12:17:52 GMT, elyob <[email protected]> wrote:
> > Okay, I'm fed up wth the noise coming from by bottom bracket and will
change
> > it before the London to Brighton ...
> >
> > I'm investigating bottom brackets and how to change. I have a crank
puller,
> > and can successfully remove and refit the cranks. Once the cranks are
off,
> > how do you get the bottom bracket out? I've not tried, as I like to know rather than bodge it.
> >
> Step 1. Buy the correct tool. (for the existing BB and the new one) Step 2. Spray WD40 liberally
> over the old BB. Step 3. Get up early the next morning. Step 4. Check, check and recheck which way
> you need to turn the damn thing Step 5. Remove the BB using GREAT FORCE. Step 6. It's now
> lunchtime. Go out to the pub for a snack and celebration. Step 7. Liberally smear anti-seize
> lubricants over the new BB Step 8. Insert the new BB making sure you don't cross thread it. Step
> 9. Tighten using a lot of force Step 10. Enjoy.
>
> (The BB I removed had plastic end caps at both ends and I had to resort to a stanley knife and
> hacksaw and someone here actually had the temerity to state that plastic doesn't seize up in
> the BB!)
>

Thanks Tim. Am on the phone to my LBS at the moment They charge £15 for the job, and that'll save
me messing it up, and having to buy the correct tools ...

 

[Peter B]

"elyob" <[email protected]> wrote in message
news[email protected]...
> Thanks Tim. Am on the phone to my LBS at the moment They charge £15 for the job, and that'll
> save me messing it up, and having to buy the correct tools ...

Not a bad idea if you don't need to replace BBs often. (I don't know what the quality differences
are twixt UN 40 and UN 52 but I do know that UN72's and UN73's have hollow shafts to lighten them
whereas the 52 doesn't.)

The advantages to DIY are obviously only buying the tool once, being able to do the job at your
convenience and most importantly being able to buy BBs from sources that may be cheaper than your
LBS. (Says he who went to his local LBS then H*lfords who both didn't stock the appropiate size then
went to next LBS who charged top dollar (well, pounds really) but was not in a position to argue).

To remove BB remove cranks, fit tool, re-fit crank bolts with washers to hold tool in place then
turn LH cup ccw to remove and RH cup cw to remove. Don't forget to remove crank bolts once the cups
start to turn. Re-fit new BB using PTFE tape or grease, preferably copper anti-seize stuff. If the
old 'un is seized follow the advice of the other poster

Alson see: http://www.parktool.com/repair_help/FAQcartdg.shtml

 

[John Hemmings]

When going for your new bottom bracket take the old one or get the sizing code of the old 'BB' to
make sure you get the correct length. Thanks, John

"Tim Woodall" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 06 Jun 2003 12:17:52 GMT, elyob <[email protected]> wrote:
> > Okay, I'm fed up wth the noise coming from by bottom bracket and will
change
> > it before the London to Brighton ...
> >
> > I'm investigating bottom brackets and how to change. I have a crank
puller,
> > and can successfully remove and refit the cranks. Once the cranks are
off,
> > how do you get the bottom bracket out? I've not tried, as I like to know rather than bodge it.
> >
> Step 1. Buy the correct tool. (for the existing BB and the new one) Step 2. Spray WD40 liberally
> over the old BB. Step 3. Get up early the next morning. Step 4. Check, check and recheck which way
> you need to turn the damn thing Step 5. Remove the BB using GREAT FORCE. Step 6. It's now
> lunchtime. Go out to the pub for a snack and celebration. Step 7. Liberally smear anti-seize
> lubricants over the new BB Step 8. Insert the new BB making sure you don't cross thread it. Step
> 9. Tighten using a lot of force Step 10. Enjoy.
>
> (The BB I removed had plastic end caps at both ends and I had to resort to a stanley knife and
> hacksaw and someone here actually had the temerity to state that plastic doesn't seize up in
> the BB!)
>
> Regards,
>
> Tim.
>
>
> --
> God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light.
>
> http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

 

[Eatmorepies]

"Peter B" <[email protected]> wrote in message news:[email protected]...
>
> "elyob" <[email protected]> wrote in message
> news[email protected]...
> > Thanks Tim. Am on the phone to my LBS at the moment They charge £15
for
> > the job, and that'll save me messing it up, and having to buy the
correct
> > tools ...
>
> Not a bad idea if you don't need to replace BBs often. (I don't know what the quality differences
> are twixt UN 40 and UN 52 but I do know that UN72's and UN73's have hollow shafts to lighten them
> whereas the 52 doesn't.)

On my Pine Mountain; UN 52, I wore out 2 in 1 year. UN72, it lasted 3 years of the same treatment -
buy XT; you know it makes sense.

John

 

[Peter B]

"Eatmorepies" <[email protected]> wrote in message
news:[email protected]...
> On my Pine Mountain; UN 52, I wore out 2 in 1 year. UN72, it lasted 3
years
> of the same treatment - buy XT; you know it makes sense.

Yeah. My Rift Zone came with a UN72 and lasted just over 3 years, I've just replaced it with a UN73,
only one removable cup and it's plastic but hopefully the bearings and seals are of XT quality. I
think XT quality tapered BBs are getting like hens teeth so next time round it'll be full upgrade to
Octalink or ISIS. Assuming no new bike :-(

Pete

 

[Marten Hoffmann]

[email protected] schreef ...
>
> "Peter B" <[email protected]> wrote in message news:[email protected]...
> >
> > "elyob" <[email protected]> wrote in message
> > news[email protected]...
> > > Thanks Tim. Am on the phone to my LBS at the moment They charge £15
> for
> > > the job, and that'll save me messing it up, and having to buy the
> correct
> > > tools ...
> >
> > Not a bad idea if you don't need to replace BBs often. (I don't know what the quality
> > differences are twixt UN 40 and UN 52 but I do know that UN72's and UN73's have hollow shafts to
> > lighten them whereas the 52 doesn't.)
>
> On my Pine Mountain; UN 52, I wore out 2 in 1 year. UN72, it lasted 3 years of the same treatment
> - buy XT; you know it makes sense.

Amazing: our first set of UN72s just left the tandem - after 20,000 kms!

--
Regards, Marten

 

[David E. Belche]

Tim Woodall <[email protected]> wrote in message
news:<[email protected]>...
>
> (The BB I removed had plastic end caps at both ends and I had to resort to a stanley knife and
> hacksaw and someone here actually had the temerity to state that plastic doesn't seize up in
> the BB!)
>

It's not, in my experience, seizing that seems to be the problem with plastic BB cups, more the way
that they tend to crack and/or chew up the minute you try and remove them :-(

David E. Belcher

Dept. of Chemistry, University of York