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PostPosted: Fri Jan 04, 2013 12:20 pm 
Old School Hero
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Joined: Sat Nov 24, 2012 5:06 pm
Posts: 231
Location: Diepenbeek
Hello everyone,

I'm restoring/preparing an older Flandria bike at the moment to sell it, but have a problem with the drivetrain/bottom bracket. A movie can say more than a thousand words, so i've uploaded a video on youtube. You can find it here: http://www.youtube.com/watch?v=zKKs6ZDkWR4&feature=youtu.be . For those who prefer pictures over videos:

Image

Image


Mainly, the problem is that the front cog weel touches the chainstay on every rotation. There's also some backlash (is this the correct english word?) on the cranks, which you can see in the second part of the movie. It also looks to me that even on the moment when the clearance between the cog and chainstay is at its maximum, it's a very small clearance? I've checked the cogs and they are not crooked or curved.

So, my opinion is that the bottom bracket is wrecked and that it needs to be replaced. But, since it probably is a french thread it will be rather expensive to find a matching one. Are there any cheaper options available? I was thinking about putting some spacer on de DS to have a bit more clearance and then fixing the backlash, if someone can tell me how :)

Thanks already for your advice, just started using this forum and it's just great!


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PostPosted: Fri Jan 04, 2013 1:20 pm 
rBoTM Winner
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Joined: Tue Apr 25, 2006 12:06 pm
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Location: Vienna, Austria
That sawing noise is going to give me nightmares


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PostPosted: Fri Jan 04, 2013 1:30 pm 
Old School Grand Master
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Joined: Tue Oct 04, 2011 4:15 pm
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Location: Behind you with the duct tape pulled out.
It maybe the bearing have just given up the gohst and with itt being a cup and cone type bb you maybe able to just replace the bearings and axle. Worse case would be a new bb.


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PostPosted: Fri Jan 04, 2013 1:46 pm 
retrobike rider
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Location: Nth Somerset, UK
First the slop in the bottom bracket: The bearings are loose or worn, so the BB need regreasing and adjusting, or replacing.

Second, the chainwheels are not square on the taper. Watching the video, if you look at the front of the bike, rather than where the inner chainwheel is touching the chainstay, you can see that either the spider is slightly bent, or that is is not running square.

Either way, I think you need to strip the BB for a rebuild and at the same time check the condition of the tapers on the driveside crank arm.


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PostPosted: Fri Jan 04, 2013 1:53 pm 
Retro Guru

Joined: Tue Oct 16, 2012 4:16 pm
Posts: 1568
Location: NOTTINGHAM
ouch - that's not too pleasant is it!

the inner chain ring looks like it's butted up too close to the BB shell - are you sure that the existing BB & axle is the correct length? the inner ring on my bikes sits about 5mm away the BB shell.

http://sheldonbrown.com/bbsize.html will give you some detailed info on set-up. also your crank-arms don't appear to be running perpendicular to the frame so that's obviously causing an issue as well.

best of luck with that one - I don't want to hear that noise again!

:shock:


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PostPosted: Fri Jan 04, 2013 2:14 pm 
Road Moderator
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Joined: Thu Jun 18, 2009 1:07 pm
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Sound advice from Neil there. Sort the bb and retry the crank checking for condition.


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PostPosted: Fri Jan 04, 2013 2:36 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader

Joined: Sat Jul 21, 2007 9:48 am
Posts: 6976
Location: Bristle
Velo Orange do a brand new french threaded cartridge BB.


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PostPosted: Fri Jan 04, 2013 3:55 pm 
Old School Hero
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Joined: Sat Nov 24, 2012 5:06 pm
Posts: 231
Location: Diepenbeek
Well, thanks all for your helpful advice :).

Regarding the information you all give, I just went to the store and bought myself a crank puller. I removed the cranks and opened the cup and cone BB. I've just cleaned the axle, bearings, the fixed and adjustable cup and the inner bottom bracket. The only thing that I found were some little pieces of scrap metal, could they be the cause of those problems? I can't see any damage on the bearings, or is it possible that the metal balls just get 'smaller'?

Anyway, the inner BB was full of dirt and now it is clean. I'm gonna clean and polish the BB shell, cranks and chainweels. After that, i'll reassemble the BB with some fresh smear and see what that gives.


Thanks again for the tips, I'll keep you updated!


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PostPosted: Fri Jan 04, 2013 5:58 pm 
Old School Hero
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Joined: Sat Nov 24, 2012 5:06 pm
Posts: 231
Location: Diepenbeek
And the result is... not that good :(

What NeilM said:
Quote:
First the slop in the bottom bracket: The bearings are loose or worn, so the BB need regreasing and adjusting, or replacing.

Second, the chainwheels are not square on the taper. Watching the video, if you look at the front of the bike, rather than where the inner chainwheel is touching the chainstay, you can see that either the spider is slightly bent, or that is is not running square.

Either way, I think you need to strip the BB for a rebuild and at the same time check the condition of the tapers on the driveside crank arm.


First part is correct: after cleaning, putting new grease and reinstallation the slop is completely gone and the axle runs smoothley. So that problem is fixed. But, the chainweel still keeps touching the chainstay on every rotation. I checked the condition of the taper and that one looks fine to me. I also cleaned the inner part of the crankarm so it looks strange to me that the problem is situated here.

What I'm gonna do: try to fit another DS crankarm and see if the problem is still there.

If so, I know it's the taper and I'll need a new axle (can you just rebuy those? Will they fit the cups, cause they have the french thread and are difficult to find/expensive?

If the problem is gone, I know it's the spider of the crankarm and I'll need a new crankset i suppose (I guess it's not fixable with a vice and a hammer :o )

Thanks everyone!


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PostPosted: Fri Jan 04, 2013 6:00 pm 
Old School Grand Master
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Joined: Tue Oct 04, 2011 4:15 pm
Posts: 3499
Location: Behind you with the duct tape pulled out.
Axles are pretty universal. Just make sure you get the correct size.


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