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Unknown bottom bracket

Posted: Wed Mar 13, 2013 2:44 pm
by WestcoastPete
Hi All

I've been given the task of rejuvinating my mother-in-law's bicycle :shock:

She's had it since new and finds it comfortable, but I've been finding some really obsolete bits and pieces on it (as in, parts that weren't around for long, and were not high end at the time). I've figured out ways around most things, until I got to the bottom bracket. I measured the shell at 70mm. Goodo; possibly Italian, probably not though. Taking the crank off, I noticed that the square taper is bigger than JIS/ISO. Oh well, I'll replace the BB and the crankset with a JIS one, I thought.

I couldn't get the drive side to budge, so I got stuck into the non-drive side and was quite surprised with the way it came apart. The lockring was more of a sleeve than a standard lock ring, and removing the non-drive side cup I found what looked like a sleeve wedged into BB shell. There are no threads cut into the shell itself. Some gentle persuasion with a drift and a hammer and the whole sleeve popped out, with the drive side cup still in the sleeve. I haven't got a vice, so am struggling to uncouple them. It's also difficult to determine the thread direction on this side. Looking at it, it appears to be a RH thread. I'd be surprised if this was correct, but it would fit in with all of the other odd stuff going on with this bike.

So anyway, what have I got here? And what are my options to rebuild? Service the existing setup and try to find a 106BCD 3-arm chainring to replace the worn one? Replace with...?

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Ta

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 3:37 pm
by RonK
A threadless bottom bracket. Not so unusual. Perhaps one of these might serve.

Grand Cru Threadless Bottom Bracket
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Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 4:01 pm
by WestcoastPete
Thanks RonK

I did look at them. I'd have to get this cup off the drive side of this sleeve and then refit the sleeve. I can't think of a better idea I guess.

Ta

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 4:03 pm
by TTar
What's that little cutout on the underside of the BB shell in the first pic? Maybe it's somehow used to remove that drive-side section? Or maybe you just punch it out the same you punch out headset cones?

Can't you just leave it there and rejuvenate around it, is the BB unserviceable?

Sorry I can't offer any practical advice, but I love these little mysteries, especially when it's someone else who's doing all the work.

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 4:20 pm
by WestcoastPete
It's a notch that lines up with a tab on the drive side cup. That's why I couldn't remove the cup without punching the whole sleeve out.

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 4:47 pm
by sturmey archer
See this thread perhaps :
viewtopic.php?f=23&t=15586

Ive got a cotter type one of these I pulled from a MS "Super Star" as museum piece... If the cups are OK maybe a standard JIS taper shaft of the right length will fit ? The threaded cup is the same thread as a normal non drive BB cup so is assume the bearing race dia will be the same.

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 6:46 pm
by HLC
WestcoastPete wrote:Thanks RonK

I did look at them. I'd have to get this cup off the drive side of this sleeve and then refit the sleeve. I can't think of a better idea I guess.

Ta


Why would you need to refit the sleeve?

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 9:00 pm
by WestcoastPete
The shell without the sleeve has a big diameter, too big for the threadless BB. But, the sleeve is only 59mm wide, which will probably be too narrow, and it's also become apparent that without the drive side cup and its little notch on place, the sleeve will rotate.

No way out of it. I'll have to rebuild it as it is. For now, I'll persist with the existing crankset too. Anyone got a 106bcd three armed chainring around? The smaller the better...

Sent from my GT-I9100 using Tapatalk 2

Re: Unknown bottom bracket

Posted: Wed Mar 13, 2013 9:35 pm
by kukamunga
If I didn't sell it at a recent swap meet, I might still have one of those bottom brackets in my collection I could sell you