gazman22

Really stumped here. I have a nice PFN 10 I am building up. The frame came with a locked up sealed BB. I removed the BB and the drive side turned out to be right threaded. I thought I was smart deducing it to be a French threaded BB and bought a new sealed French BB. I go to put it in and it is clearly not going in. The threads lock up immediately.

I then reinspected the BB I removed (I now will pay more attention to markings on BB after removal!) and see that it is a Shimano BB-LP30 and is a 1.37 x24 (English threaded). It also has the "L" marking arrow pointed to the fixed cup. So the fixed cup side is on the left side of the bike and is right hand threaded. The drive side is the adjustable cup and is also right hand threaded.

I look on Sheldon Brown and the only right hand threading on left and right side of bike are French (which I know does not fit) and Italian which is not a match for diameter.

I am stumped! What is this threading? And, how do I replace this BB? am happy with a sealed or loose ball BB.

Any help is appreciated.

Gary

juvela

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at the 1978 model launch for the PFN10 the chainset was a model 104bis

it this what came with your example or is it something else?


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Mr. 66

That may be of Swiss thread

gazman22

I only bought a frames but the bike originally came with a Stronglight 104.

gazman22

Per Sheldon Brown, Swiss threading is left hand threaded on the drive side and 35mm x 25.4 tpi.

Mr. 66

Yes, probably Swiss. I think I had that model (they ride great!). It, when I bought, had a Shimano cartridge bb installed. The English will thread in Swiss about 4 turns before the breads bind, can be forced to full insert. I found a Swiss bb at the local coop for it.

billytwosheds 

Could it be two bottom brackets cobbled together?

gazman22

The only way a Swiss BB would fit is if I installed it backwards with the fixed cup on the non drive side and then used right hand threaded cup on the drive side. Do you remember if this is what you did?

gazman22

Dunno— just cant figure out what the original shell Was tapped for?

Mr. 66

Here is what I had.
I was trying to set a triple on it here but I discovered the braze-on simplex version didn't handle the swing needed. I ended up putting original type back to it. I sold this because of that. The other thing I didn't like about it was the seatpost, the saddle would float back extending my reach gradually, lols. I took the Weinman brakes off and swapped with Superbe

Mr. 66

I know what I had was Swiss. Peugeot had some curveballs, some were made in Canada and Australia. At the time I think only Pug, the PX-10 had French threads, all the rest were Swiss. Again this is Peugeot just a year or two earlier all would have been French, and a few years later all were made with English. The different plants also could have different thread for the locations of sales.

billytwosheds 

My guess is French, and whoever last did work on the BB ended up forcing in a RH-threaded ISO adjustable cup onto the drive side of your bike.

The fixed cup might still be French.

Have pics of the bottom bracket you removed?

gazman22

So maybe I should carefully see if I can get the French BB I bought in? Try to reform the threads back to French.

juvela

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recall that lower model P's of this time were CH

their bottom bracket fittings were oro finish

the code to indicate CH thread for the fixed was knurling on the edge of the cup



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gazman22

Sorry, what does CH refer to?

juvela

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CH is the two-letter designation for Switzerland


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awac

If you find this is a Swiss thread bb, put details of the bike/bracket on here if you can. I bought a frame which had an English thread cup inserted into the frame with a thick washer against the frame to tighten against because it did not want to go all the way in. Lucky no damage, but the Swiss cup in now fits as it should.

https://www.bikeforums.net/classic-v...bb-cup-id.html

oneclick 

That won't work.

A swiss fixed cup is left-hand.
All* non-drive side bb shells are right-hand.
* for some large value of "all".

billytwosheds 

Look for markings on the fixed cup.

Sheldon Brown's page can be useful in understanding the differences between BB shells, cups, etc.

https://www.sheldonbrown.com/gloss_bo-z.html#bottom

Right-hand thread on both cups still tells me French.

But I have known to be wrong before.

Re: installing the new French BB, I would be wary of trying to reform deformed threads from French > ISO > French.

The threads on the BB in your pic look a little mowed down, which again makes me think it was forced in.

Hondo6

FWIW: some of Shimano's early cartridge-type BBs did have the flanged cup on the NDS vice the DS. The BB-LP30 was one of them.

I'd love to see a picture of the DS cup that you removed from your existing frame.

gazman22

Here you go. Not much to see. It is marked 1.37 x 24.

It also does not fit the BB very well. it is loose. No surprise there.

I did try to install the removed BB and non drive side cup into another English threaded BB bike and they went in fine.

gazman22

Tend to agree shell was originally threaded French. Only thing that seems contrary to this is Sheldon Brown has a chart that shows what happens when you try to mismatch BB and threaded shells. For French shell and English BB it says BB goes in loose. So, not sure why I would have so much trouble putting in French now.

Seems like only two choices:
1. try to insert the French BB with fingers crossed.
2. try to locate an old BB with English threading and flanged cup on non drive side (and then locate adjustable cup that fits the BB body). This sound painful.

3. Wildcard choice...install loose ball BB with two adjustable cups and loctitie? Doable?

Hondo6

Agreed. If both sides of the shell were originally RH threaded, it's either French or Italian. Shell ID rules out Italian.

Forcing in English RH threads on the DS, even as a loose fit, would likely have deformed the existing French threads to some extent because the thread pitch is slightly different(25.4TPI vs 24TPI); I'd guess that the outer threads would be damaged the most. I'd also guess that (damaged threads) is why your new French threaded BB is going in with difficulty.

My guess is that (1) both of the flanged cups you found on the bike are RH-threaded, and (2) someone pried a flanged RH-threaded endcap off the NDS of a later English-threaded cartridge BB and used that in place of the existing DS encap that came with the BB-LP30 you found installed in the frame.

IMO you actually have two reasonable, if not perfect, other choices:

a. Find a LBS that still has the equipment to chase French threads and have them do it. Upside: might save the frame for use as originally intended (e.g, with French-threaded BB). Downside: unknown cost; might not be available in your area; may or may not help.

b. Get a "repair" threadless bottom bracket. YST makes them to fit 68mm shells in several spindle lengths; a few weeks ago, they were available on both Amazon and eBay. (VO previously offered a similar product, but seems to have discontinued theirs.) Upside: this should fit without doing further damage. Downside: might not be able to find the exact spindle length you need; all of these I've seen except one were JIS (and I suspect the single ISO listing I saw was erroneous); additional cost; OK but not stellar quality.

In your shoes, if I knew of a LBS that knows vintage bikes and I could trust to do the job right, I'd inquire with them about option "a". If that were reasonably priced, I'd probably try that first - because one of the threadless "repair" BBs will be around $30 plus S/H.

Your bike, so your call. Best of luck.

Chombi1 

That bike came out right when Peugeot was still making hard efforts on implementing Swiss threading on their BBs for many bike models in their product line.
They pushed the Swiss threading up to the 84 model year, my own example being my 1984 PSV that has it.

John E

My 1980 PKN-10 was definitely Swiss-threaded. Because of cup wall thickness / spindle length compatibility requirements when I converted to a triple, I force-threaded an aluminum English fixed cup, and it has held fine for more than 10 years now. I just leave it in place when servicing the BB.

My old PKN-10, now my son's kiddie-puller, although the boys are getting big for the trailer now.

Picture is from a few years ago. The boys are 8 and almost 6 years old now, and ride their own bikes, but my son certainly appreciated my granny chainring back when he had to pull them in the trailer.