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raleigh olympian and upgraded 70's varsity BB swap - no go

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raleigh olympian and upgraded 70's varsity BB swap - no go

Old 03-21-11, 08:26 AM
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nowitsshowtime
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raleigh olympian and upgraded 70's varsity BB swap - no go

Note - I'm not a noob at wrenching. Worked on plenty of cars.

Problem is on the BB, one of hte "cups"? goes on smoothly and can get threaded far by hand, the other 3 parts in the swap get threaded a few times before they are impossible to turn by hand. I'd have to drive 1/8th of it home hard with a wrench. This does not feel right.

Details - I have a 70's varsity with an IRO crank and BB, and the bb adapter. This is ********, I know, so I was going to take the stock Sakae CX '84 Raleigh Olympian crank/bb and put that on the varsity, and IRO crank and bb on Raleigh.

One of the threaded ends of the Olympian bb thread into the Varsity bb converter, the other does not. None of the IRO BB fit into the Olympian. But if the one end of the Olympian original BB fits into one of the varsity bb converter, how could none of the IRO BB fit into the Raleigh. Did I just mind **** everyone including myself? Should I just force it, sort of nervous.
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Old 03-21-11, 08:38 AM
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nowits -I'm going to move this to the mechanics sub-forum.
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Old 03-21-11, 09:06 AM
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Don't force it. Although the Raleigh's BB is the same diameter, the thread pitch is different- 26 TPI rather than the standard 24 TPI. This means that you'll be able to get about 3 turns of one into the other and then you're stuck- any more will ruin the BB shell. There are a number of "solutions" to upgrading a Raleigh BB, including rethreading the BB, grinding off all but three rows of threads on a cartridge BB, getting a Phil Wood BB with 26 TPI cups, tapping the whole thing out to Italian specs, etc. Lots of threads about this here.
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Old 03-21-11, 11:29 AM
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Originally Posted by cycle_maven View Post
Don't force it. Although the Raleigh's BB is the same diameter, the thread pitch is different- 26 TPI rather than the standard 24 TPI. This means that you'll be able to get about 3 turns of one into the other and then you're stuck- any more will ruin the BB shell. There are a number of "solutions" to upgrading a Raleigh BB, including rethreading the BB, grinding off all but three rows of threads on a cartridge BB, getting a Phil Wood BB with 26 TPI cups, tapping the whole thing out to Italian specs, etc. Lots of threads about this here.

This makes sense, but why would 1 out of 4 cups swap. And nothing is stripped or threaded differently. Thanks for the input though, I'll have to do some research what to do or what to buy. I'd probably prefer to tap the raleigh if possible.
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Old 03-21-11, 04:33 PM
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On second thought, by 1984, I think Raleigh's were English-threaded (I mean 24 TPI). So there may just be a slight difference in diameter- the smaller cups go into the larger hole, but not vice-versa. Left cups won't go into drive-side holes at all- drive side of the BB is left-hand threaded- so only one cup fits... Or I'm completely full of s**t and I'm just guessing now.

Try making sure the cups have the same thread pitch by laying them side-by-side to make sure the 26/24 TPI thing is irrelevant. If they're all the same, then running a thread chasing tap through the Raleigh will most likely help. Keep aware the left-hand threading on the drive side.
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