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Old 08-06-08, 03:28 PM   #1
TromboneAl
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Centurion Bottom Brack Overhaul

I'm getting ready to do my first bottom bracket overhaul (that is, inspection and repacking). This is on a Centurion Dave Scott Ironman Expert from 1987.



Can you tell me what kind of bottom bracket this is, and what tools I'll need (including tools for removing the crank)?

Thanks!

Last edited by TromboneAl; 08-06-08 at 03:36 PM.
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Old 08-06-08, 03:47 PM   #2
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It looks like a standard cup and cone BB. You'll need a 14mm socket wrench to remove the crankbolts, a crankpuller to remove the cranks, and a spanner and a BB pin tool to remove the removable cup of the BB. The fixed cup can stay in the frame.

Spanner: http://www.parktool.com/products/det...5&item=HCW%2D5
BB pin tool: http://www.parktool.com/products/det...5&item=HCW%2D4

And if you do need to remove the fixed cup, remember that it is reverse threaded
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Old 08-06-08, 04:04 PM   #3
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Quote:
Originally Posted by orangepaint View Post
The fixed cup can stay in the frame.

Spanner: http://www.parktool.com/products/det...5&item=HCW%2D5
BB pin tool: http://www.parktool.com/products/det...5&item=HCW%2D4

And if you do need to remove the fixed cup, remember that it is reverse threaded
The fixed cup can stay in the frame if it isn't damaged and if you plan to clean, lube and reinstall the current bottom bracket. If you expect to or have to replace the bb, the fixed cup will have to be removed and, as noted, the threading is left-handed or the reverse of "normal" It will unthread clockwise.
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Old 08-06-08, 04:46 PM   #4
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Thanks, that gets me on the right track.

Do I need another pin wrench to remove the crank dustcap, or should I be able to jury rig something?

Any chance that the cranks are self-extracting, or is that only for newer bikes?

Will any crank puller work, or do I need to match it to my cranks?

The ball bearings will probably be in a retainer cage, and if they look OK I can use them again -- does that sound right?
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Old 08-06-08, 06:47 PM   #5
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Quote:
Originally Posted by TromboneAl View Post
Thanks, that gets me on the right track.

Do I need another pin wrench to remove the crank dustcap, or should I be able to jury rig something?

Any chance that the cranks are self-extracting, or is that only for newer bikes?

Will any crank puller work, or do I need to match it to my cranks?

The ball bearings will probably be in a retainer cage, and if they look OK I can use them again -- does that sound right?

1. you can rig it. if it's that plastic cap with 2 holes, stick a couple small (2mm) hex wrenches or something else like that and give it a push counter clock-wise

2. no chance

3. any square taper crank puller that's not pre 80's Stronglight, just about anything you'll find to buy.

4. yes, and why? they're so cheap to replace. buy 1/4" grade 25 balls at your LBS for <$5. you can probably reuse the retainer, or ditch it and add an extra ball (or two) for even better performance.
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Old 08-06-08, 06:48 PM   #6
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You might as well put a $20 shimano 105 quality cartridge bb in there while you're at it. No maintenance and lasts nearly forever. No stupid cone adjustment, no stupid lockring and no stupid cup with tiny little holes to get seized with.
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Old 08-07-08, 08:28 AM   #7
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You might as well put a $20 shimano 105 quality cartridge bb in there while you're at it.
That sounds too good to be true. What's involved in that?
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Old 08-07-08, 10:51 AM   #8
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1 Find a 105 level BB that takes square taper cranks.
2. Find one for $20.
3. Get through 1 & 2 first.

The cup type are fine. Don't replace with a cartridge unless the cups or spindle are damaged.
You can use a large curved jaw vise grip pliers to remove the lock ring & fixed cup. A couple small Phillips screw drivers should be able to spin out the movable cup.
Get 22 new 1/4" BB's & grease. BB's are relatively cheap at the LBS, and you can save the hassle of cleaning & inspecting the old ones. If you reuse the old ones, the anal way of doing it "right" means you keep each set of 11 with them selves. One bad one and you replace that set. Why screw around with the old ones?
IF you were to install a cartridge, you have top determine WHICH length for the new one. That may or may not be simple.
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Old 08-07-08, 01:16 PM   #9
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All information to this point has been accurate.

One minor point has been omitted. If you do decide to upgrade to a cartridge BB, you will want to buy the appropriate tool to install the cartridge BB (about $10-$15 as I recall) at the LBS.

You have at this point now spent more money on tools than it would have cost to have the LBS do the work. However, you will have had the satisfaction of doing it yourself, and if you continue to do your own work, the investment in tools will be worthwhile.
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Old 08-07-08, 04:32 PM   #10
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Another crucial point that has been missed: You need to have the same length spindle on your new cartridge bottom bracket.

Darwin is totally right; if you don't plan on ever doing it again (and you won't have to on this bike once you put in a cartridge), then it makes more financial sense to take it to the LBS.
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Old 08-08-08, 01:40 AM   #11
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Make sure the crank puller you use is for square taper...otherwise you'll just strip the crank threads.
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Old 10-18-08, 05:39 PM   #12
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An update on this post:

I finally decided to have the cartridge put in, and was told that it would be $29 for the cartridge and $40 for the labor. But when my wife dropped off the bike, they told her they wouldn't know how much it would cost until they got the part, and couldn't estimate when it would be done. They took the bike, and didn't even give her a claim check.

I called them up and told them to cancel the job; I'd pick the bike up in a few days.

They called back later, very apologetic, and said that they'd do the job for free, just charge a little for the part. It now has a new BB. Total cost: $16.00.

When I take the chain off and spin it, it doesn't spin for as long a time as it did before the replacement. Is that reasonable/expected?
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Old 10-18-08, 06:12 PM   #13
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Originally Posted by TromboneAl View Post
When I take the chain off and spin it, it doesn't spin for as long a time as it did before the replacement. Is that reasonable/expected?
On a new BB, that is exactly what you want. (Assuming it is not binding or gritty, just not spinning much before slowing and stopping.) Go ride it for a few hundred miles and then spin it again w/o the chain, it will be like butter.

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