greg3rd48 

I have worked on a few French bikes now and know the differences yet I have never encountered this issue prior to tonight. I am building up a UO8 as a townie and stripped it down completely. No issues. Cotters came out in a jiffy and the BB cups came out pretty easily. I used Sheldon's tool for the fixed cup and it worked as always. Cleaned out the BB and tried to thread in a new set of Action French threaded cups. The non drive cup goes in perfectly. The fixed cup not so much. I have tried every which way to thread it in but it stops about two turns in and looks as though the from part of the cup is out of the BB a tiny bit more than the rear. I tried to thread in the original fixed cup and had the same problem. What could be the problem and how can I overcome it? I have used these cups on another UO8 and they work perfectly after over 1500 miles. I can take photos also if that helps but I am stumped.

oddjob2

Use the old cup with some grease to clean the threads.
Copious grease on the new cup. Fixed cup installed first obviously.

juvela

a) could be manufacturing tolerances.

b) could be swiss, there have been periods where some Peugeot models were swiss threaded.

c) one can use and old cup to make a thread chaser by grinding grooves in the threaded area perpendicular to the threads. sort of a poor man's bottom bracket tap.

greg3rd48 

I am almost positive that it is French thread. It is about a 76 UO8. I should take a picture in the morning. The old cup went in maybe another turn more but it still didn't thread all the way. I am hesitant to apply too much force. Should I avoid forcing it?
@juvela I am a little confused about c. Do you mean I should force in the old fixed cup as a tap if nothing else works. Thanks guys I appreciate any help. I dropped the tools and walked away frustrated after an hour of trying.

juvela

if fixed cup has oro finish and knurled edge it will be swiss.

not suggesting force in cup. c) is instruction as to how to easily and cheaply make a thread chaser. cups turned into thread chasers are tools to be kept around.

greg3rd48 

It is definitely between a 76-78 UO8. The decals are of that style. The thread of the BB look fine. I believe this was the first time evert that the fixed cup was removed from its orinal position.

CroMo Mike 

Find the beginning of the cup's thread and mark it with a sharpie. Find the beginning of the bb thread a mark it. Clean up the beginning if needed. Hold the cup against the bb and rotate it backwards until you feel the beginnings click over each other then carefully rotate forward to pick up the first thread without cross threading.

JohnDThompson 

Like this:

merziac

Take a right angle pick, 45 degree and chase the threads from the inside out with the sharp point. Use good pressure and be very careful to feel your way through it. You will probably find the cross thread and be able to correct it somewhat with the pick point. Then use anti seize reseat the cup and clean out the anti seize before final assembly.

eschlwc

swiss uses french thread dimensions, but in the reverse for the fixed cup.

rhm

Would a Swiss cup thread in at all? I haven't tried, but it seems to me it would never even start.

If the frame has French threads, a French adjustable cup should thread in.

hatrack71

If it is French threads, it is counter clockwise to loosen and clockwise to tighten on both sides. The reverse of British.. on the fixed drive side.

rootboy 

If the original fixed cup came out of there, it will go back in. I suspect you're just experiencing a bit of binding. That you didn't feel so much upon removing the cup. Shell could be ever-so-slightly out of round. Clean out the threads with a wire brush best you can, coat the threads with oil and install...in and out. It should clean up the entry and exit using oil. If it works, then use grease.

greg3rd48 

@rhm, @juvela and @hatrack71 It is definitely French threaded and threads on a couple of turns but it feels like there is a block after that. It sounds like chasing the threads to clean them out might remedy the matter but I do not have a tool to grind out a groove in the old fixed cup. @merziac I may have to try your suggestion. So this may be a cross thread not just foreign particles that are blocking the threading path?

greg3rd48 

@rootboy That sounds doable. I wondered about a wire brush but was reluctant because I did not know if I would damage the threads with the brush. You know better than I so I will try this first. Is WD40 or Anti-Seize appropriate to use as the oil?

hatrack71

I somehow overlooked this. You are cross threaded. You'll need to get it started right and it can be a pain. I sometimes will turn the cup in the loosening direction and wiggle it until it comfortable finds the right seat square to the shell. Hold it as square as you can while turning it. However, since it was threaded two turns already.. even loosely.. in a cross threaded fashion.. this could be tough.

mparker326

I have had that issue before with older bikes. Fixed cup threads out, but won't go back in. Chasing the threads fixed the situation.

rootboy 

A wire brush shouldn't damage the threads. Read that as hand held wire brush, not a powered one. Just to clean out the threads. I wouldn't use anti-sieze compound. And WD-40 may be too light. Oil will help with a slight "cutting" action, to help clean up the threads a bit too. But when you install it for good, clean off the oil and grease it.

The home-made thread chaser with the notches cut into the threads is a cool one. The notches in the thread circumference act as gaps to take up the "chips", or any debris, like a tap, or chaser. Which keeps them from lodging between the cup and the BB shell threads, which may cause binding. Great idea.

juvela

Threading (tapping) in always the first choice. When unfeasible chasing is the second choice. When chasing not possible a wire wheel is the next best option.



McMaster-Carr

Readily available at any hardware store.

due ruote 

Have you tried threading the adjustable cup into the fixed side? If it goes in OK I would oil it up and thread it in/out a couple times but without fully removing it, then take it out and try the fixed cup.

jcb3

I recently worked on 2 ~1973 PX-10s that had Shimano French cups installed and both drive side cups were really hard to get out, I mean really hard.

The threads looked ok (although 1 of them was a bit buggered where the chain stay is brazed into the bottom bracket - on the PX, there are only a couple threads on that segment of the bb before jumping over the chain stay - although it may have been the brazing itself that was tapped through and has come off).

However, the non drive side floating cup threads in with a lot less effort (on the drive side) than the drive side fixed cup - I have not dug further into this matter (measurements, etc ) but seems on the Shimano cups, the drive side fixed cup may be slightly larger (tighter) than the non drive side cup.

Just a thought....

greg3rd48 

@due ruote No I haven't tried. I am going to have at it again after work later today and if that doesn't work try again this weekend. I hope that something works, everything was going so smoothly until this. If these threads are shot is the only option a threadless cartridge?

Ed.

Somewhere, a long, long time ago, probably in a galaxy far, far away, I saw a bottom bracket that had been tapped straight through, one side to the other. If this one is like that, you could try running the adjustable cup all the way thru from the left side.

A 'chaser' can be easily made with an adjustable cup, using a triangular file to create notches perpendicular to the threads. Fancier, but more difficult, is to cut 'V' shaped pieces out of the cup, to create a saw-tooth profile.

Good luck!

juvela

Excellent point!

There are manufacturing tolerances/variations on these, even Campg.

Back in the mid-'70s I spoke with Don Millberger, the person behind Bicycle Research Products of Concord California. He said that at the Schwinn Paramount facility they had a bin of Campag NR BSC cups which were too large for the bb shells on the bikes, even though they were using Campag bb taps. So he intentionally made the Bicycle Research bb taps several thousandths oversize to accommodate.

merziac

Could be either, using the pick will show you will show you what is going on if you look closely while doing it. You can use the pick to help correct the crossthread by carving/digging carefully with the pick. You also should do the same on the cup, the more you clean up both, the better it will be.