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-   -   Non symetrical size threading on bottom bracket (https://www.bikeforums.net/bicycle-mechanics/1225833-non-symetrical-size-threading-bottom-bracket.html)

schiavonec 03-14-21 03:12 PM

Non symetrical size threading on bottom bracket
 
This is a really odd issue. I've swaped out dozens of bottom brackets over the years. 1994 marin palisades recently purchased as an old school mtb. I have a tange bb with a steel non drive side unit vs the cheap plastic opgion with many shimano units. The original shimano was seized, but after some work, i got the drive side out. The non drive had a plastic unit. I cleaned the houding with a wire brush. I put the tange drive side in without issue, but the non drive was really tight after just a few threads. I pushed it a bit but it became clear metal was digging into metal. I pulled it out and it looked a tiny bit reduced in diameter with some metal shavings. The original plastic is to small for the diam of the tange unit, so i put the orig one back in. What am i missing? This has never happened before. I would like to upgrade many components so it is more efficient.

Iride01 03-14-21 03:37 PM

Working on bikes you are going to find odd stuff and things that don't work like they should. Or don't work like you thought they should.

Working on old bikes, you'll encounter even more of this. There are an endless (not literal) list of different bottom bracket sizes and threadings for those that are threaded.

If you can't tell us what you have by year, make and model, then pics will be a big help.


or are you just venting and just want some commiseration?

schiavonec 03-14-21 03:54 PM

I measured the spindle length and compared it to the tange unit. (Same length). I surfed around for a while attempting to get spec info on thd original unit but shimano sealed is all i could find. I've worked on old French road bikes, old cottered crank eng roadsters, tons of bmx bikes in my youth with 3pc and 1 pc units, many 90s mtbs (steel and aluminum) many 80s/90s japanese road bikes in steel... and have not had this issue. Just curious if others have had this issue. I will try to dig up some more details. Seems like the tange cup/sleeve is the issue.

new unit tange bc 1.37 x 24t
68 x 110.5
090146

number on bottom of bb shell
174HA0284 (1994 marin palisades model)

I pulled the old unit, cleaned it up and the only marking on the plastic cup says the same thing 1.37 x 24t.

The tange unit worked well with a former 97 khs summit mtb 110.5 x 66 1.37 x 24 with no issue.

Andrew R Stewart 03-14-21 06:49 PM

Mixing thread specs between the two ends of a BB shell is pretty much unheard of, especially with a price point mass produced bike. Instead I suspect that there's some thread damage , rust, or initially poor factory chasing of the OEM threads. That plastic LH retainer ring (not really a cup at all) would mold it's self to whatever threading was there, steel being so much harder then plastic is. One possible solution is to do the thread chasing now. Better shops should have BB threading tools.

If one is doing a lot of this stuff (for themselves, friends or to flip bikes) then having a relationship with a LBS will have serious value at times. For info, advise or to do the operations that one can't do. Since we don't know where the OP is we can't give much help to a LBS location. But there's the phone and it only takes a few minutes to call around (assuming the OP has a phone and a local population that supports a LBS.)Andy

dedhed 03-14-21 07:22 PM

Get the BB chased and it'll go in like it should.

dsbrantjr 03-14-21 07:52 PM

You might also find that getting the non-drive side started before doing the final tightening of the drive side will help you get the alignment correct more easily.

cbrstar 03-14-21 09:11 PM

You are using a NOS tange set? I'm wondering if somehow the cups are missmatched. One side is English and the otherside is ISO? Iso is just very slightly larger.

Jeff Wills 03-14-21 10:02 PM


Originally Posted by cbrstar (Post 21967629)
You are using a NOS tange set? I'm wondering if somehow the cups are missmatched. One side is English and the otherside is ISO? Iso is just very slightly larger.

One side English and the other side Italian? Possible if the threads were stripped at one point and the stripped side was retapped Italian. Very, very unlikely though.

I'd also consider that that frame might have been dropped and the bottom bracket shell is slightly ovalized.

In either case, the way to salvage the frame is to have an experienced frame person run taps into both sides. As with many things, one definitive measurement is worth a thousand Internet opinions.

andrewclaus 03-14-21 10:32 PM

I recently had a hard NDS cup fit on a similar BB. With careful cleaning and greasing and running it in a couple of times without the cartridge, I got it to seat right. It was just corroded.

schiavonec 03-14-21 10:32 PM

Thanks to all for the comments. I will check on the cost of a rethread, etc. It may be beyond my budget for the intended use given the need for upgraded brakes, raised stem, all new cables, too. I am not a flipper and this is for rv travel exposed to weather, and to go on some trails with my son. I am beating up my cyclocross bike in the interim.

dedhed 03-15-21 08:54 AM


Originally Posted by schiavonec (Post 21967691)
Thanks to all for the comments. I will check on the cost of a rethread, etc. It may be beyond my budget for the intended use given the need for upgraded brakes, raised stem, all new cables, too. I am not a flipper and this is for rv travel exposed to weather, and to go on some trails with my son. I am beating up my cyclocross bike in the interim.

Last time I had it done I believe it was $20 to chase & face with me bringing in a bare frame

dedhed 03-15-21 08:56 AM

If you have the confidence in your skill set.


philbob57 03-15-21 02:35 PM

My bike's BB is Italian on one side, English on the other. When I bought the frame, used, in 1981, one side of the BB had been cross threaded. After 15 minutes of trying to get the English cup to work, my guy at the LBS (an art student named Mike at Turin in Evanston) did some checking in a manual and said that Campagnolo recommended re-tapping as Italian. He worked so hard retapping the BB at no extra charge that I didn't want to suggest retapping the other side to Italian, too. So my BB is half-Italian, half English.

At the time, I probably didn't know the BB widths were different. I was going to put the bike together with a lot of parts from Turin's stash - for example, Mike found a Campy-copy seatpost branded 'Arius' - and it was easy to find an orphan Italian cup.


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