motebecane bottom bracket question
 

Hi,

I have what I believe to be a 1978 Motebecane Mirage. I had taken apart the bottom bracket to grease the bearings. When I reinstalled it, there are a couple of threads showing on the piece that holds the bearing in which are not covered by the outer "ring". I can't remember if this was the case before(i.e. the outer rng was flush with bearing holder). It is not the threads as if i remove the bearings I can fully thread the piece in.

Any ideas? It is a Sakae crank assembly.

Thank you

Drive side or adjustable side? I am assuming adjustable side. Sounds like you lost the lock ring. Easy enough to get one at your local bike shop or friendly flipper.

Hi, adjustable side. The lock ring is what I called the outer ring(still unsure of all the names). After putting the lock ring on, there are 2 threads showing, so I am thinking that is not correct, but I can't tighten it anymore.

Did you use new bearings? If so, did you make sure you used the exact same size that came out of it?
Sounds like your adjustable cup is sitting further out than it did before you removed it, and that there are now
more threads showing on it when you install the lock ring. If you used the same spindle, the only thing I can think of might be over-sized bearing balls.

Oh, wait... when you installed the spindle back into the bottom bracket, did you make sure to put the "longer" side on the side that the drive side crank attaches to? Maybe you installed it backwards? Don't know if this would affect things like you say.

All other things being equal...two threads might be normal.

Take it apart, and check for issues. Did you reuse the caged bearings? If so, I bet they are in backwards. +1 old spindles were asymmetrical, so make sure you have it in the right orientation (longer end on the drive side). But that will not affect the adjustable cup.

I never reuse caged bb bearings. First, they are likely 30 years old or more. Secondly, replacements are cheap, 2 cents each in bulk, or less than 50 cents for an entire bb rebuild. Third, I prefer 11 loose balls over 9 or so caged balls. Fourth, I have seen a lot of bb damage from the damn retainer ring.

Threads sticking out are not uncommon.

I usually tighten the left side cup until there is no slop in the spindle moving in/or out. I give the spindle a turn to see if it's binding. If it binds, I back off the left side cup until there is no binding, usually 1/8 to 1/4 turn. Then I put on the lock ring and tighten it down, making sure not to turn the left side cup.

thanks for the replies. I will take a look at it again. I had flipped the axle around(it looked symmetrical). the balls our facing out, which seems correct, otherwise they could fall into the shaft.

Sounds like cages bearings. And that you have them in backwards. "open" side of the cage should face the spindle surfaces.
Good one, wrk101.

ok..That would be the one thing I haven't tried. I will try that next.

+1 Once you get them in right, don't tighten it as far as you can. You need to adjust the bb, to get the proper setting. The way I do it is I get it close to right, just a tad loose. I then install the driveside crank only (leave the non-driveside off). I spin the crankset (no chain), and see if it wiggles. Typically, there will be a little play between the crank arm and the downtube (squeeze it). Then adjust the adjustable cup as necessary. That takes TWO wrenches, a lock ring wrench and a cup tool. I adjust the cup until the play is gone, then hold the cup in place while I tighten the lock ring.

update...I had installed correctly originally. seems like a couple of threads will show. I ended up getting new cage bearings. The concern now is that they appear to be slightly bigger(cage side). My guess is the are 1/4 inch and probably need to be a slightly smaller size in metric. The bike shop seems to think they gave me the correct size. At this point I am wondering if overtime the spindle will wear to match the slighty different cage bearing(it seems like the wear is coming from where the cage hits the spindle bump to keep the bearings against the fixed and adjustable pieces. I would reuse the original, but one has been bent.

This is sounds pretty normal for this type BB when adjusted it is pretty common to have a couple of threads showing.

I never use caged bearings on bb as they cost more and are inferior to loose bearings. I've done quite a few Motobecanes, they have always taken 1/4 inch bearings. Easy enough to check with a caliper.

I think the ball bearings are the right size. Looking at the cage, it seems slightly different. That is why I think it is now wearing on the spindle(can hear it, specially on hills). At this point I am not sure what other option I have then to hope that the wear finishes soon and the noise goes away. I don't think I could use loose ball bearings as they would probably take some coordination on my part as there would be nothing to hold them in, especially on the fixed side. So solving one problem created another.

I wouldn't let the cages wear on whatever it is that they are touching. They don't sound to be the correct cages. You know you can pop the old bearing balls out of the old cages and put new balls in those cages (as long as you are careful not to bend the cages)? As mentioned, if you use loose balls (11), the grease will hold them in just fine. You are using grease (and a good deal of it) aren't you?

I did use grease...I will look at the one cage that was slightly bent coming out. might be better to fix that than use the other cages. I can apply extra grease at that time as well.

Why not just ditch the cages altogether? Use loose balls. It's a better thang. A little harder to do, but not that difficult.
Just make sure you use the correct number on each side.

so from 9 to 11 for loose? pack the grease and push the balls in? I didn't plan to take fixed side off, but could pack with tweezers. I wasn't sure the spindle could contain/hold them Against adj and fixed pieces. it has a lip, but wasn't sure if big enough

Yeah, no need to remove the fixed cup. Got a way to line that cup with lots of grease? I usually just squirt some on my finger, then stick my finger in the spindle hole in the cup, and wipe it in the races of the cup. Go 'round and do several of those so the cup is well-filled. Then you can stick the balls in the same way. Or drop them them in with tweezers or something. Then, lower the LONGER end of the spindle...frame laying on its side of course...down into the bottom bracket shell and captured the balls against the fixed cup with spindle. Then, lower other, adjustable cup, also filled with grease and 11 balls, down onto spindle and screw in to finger tight. Screw lock ring on adjustable cup. Upright bike in stand and adjust bottom bracket.

Careful not to dislodge any of the balls on either side doing this. Use plenty-O-grease. Too much is better than too little and it holds the balls in better.
Balls should be completely covered with grease, or nearly so.

No "from" 9 to 11. Has to be the right number. Should be eleven, 1/4 inch balls. Each side.

As mentioned, these use 1/4 inch bearings (didn't want to confuse the OP).

That does bring up an interesting question though... since everything else is metric (in std. road bikes), why aren't the bearings metric?

I always wondered that too, Pars. More learned bike-o-philes than me will have to answer it.
campagnolo even used Imperial threading on some fasteners.
Enough to make me scratch my head.

ok. used 11 balls on each side and packed with grease. pedals do not wiggle side to side. still get a muted tweeting noise when pedaling. not as bad as before, but there.

yup -- always a couple threads showing of the adjustable cup after the lock ring is tightened and the bb is perfectly adjusted.

don't worry about number of threads showing. worry about tightness and smoothness.

Maybe the noise is your pedals, or chain, or something else. How are your knees?