bottom brackets replacement 80's bianchi
 

i took it out last year to clean it, but im thinking i might just replace it. is this a better idea, and how do i know how to get the same one?

The only reason to replace is because it is worn out or scored in some way that it doesn't spin freely. Take it back apart and the cups should be marked 35x1 or 137x24 ect. as to English or Italian and the match the axle dimensions. If it is campy get the replacement campy as I think it is a better unit than Shimano and the taper is slightly different, I dont like itas well but it has worked in the past.

it just turns slowly

You may have set the pre-load too high when you re-installed it.

There should be no play and no undue resistance, grinding, or explosions.

i just figured it was dirty because it was old. i havent put it back in since i've cleaned. i guess i should see if that helps first before i decide to replace it.

Err, make that "36 x 24F" for Italian and "1.37 x 24tpi" for English.

"35 x 1" is French.

Inspect the bearing races on the spindle and in the cups. If shiny and smooth with no pitting, you can re-use these parts. Replace the ball bearings. Make sure the spindle and cups are really clean before greasing and installing the bearings. Most BBs take 1/4" balls. Get the 'Grade 25' bearing balls. You can either pop the old bearing balls out of the cages and replace them with the new, or just stick the loose balls in the cups with grease. Removing the cage will allow maybe two more balls on each side - typically you remove a 9-ball cage and replace it with 11 balls.

sorry for reviving an hold thread, but i never managed to get around to actually fixing this. i never understood what everyone was saying the first time, so i took a couple pics this time.

these are all the parts that came out of the bottom bracket area. im having a hard time removing the opposite side of the piece in the top left corner, but i can clean it from inside. im not really sure what pitting is, is there any in the detail shot? should i just get new bearing, grease everything up, and put it back together?

http://i.imgur.com/BTHJ2.jpg

here is more detailed shot
http://i.imgur.com/NNpYk.jpg

The opposite side you are referring to is the fixed cup. If you can see it and it looks OK, just clean it as best you can and leave it be. If you REALLY want to take it out, I would suggest taking it to a bike shop to have it removed (IMO). The pitting to look for would be on the bearing cup(the part in the upper left), more specifically you want to look at the bearing race, which is the shiny smooth part the that the bearings fit into. Pitting refers to just that, "pits" in the surface of the race or bearings. From what I can see the cup looks OK. I cant tell if your bearings are pitted or just dirty in the above photo.

My recommendation would be to clean everything really well and put it back together. If you clean the bearings and they still look rough, I would replace them. Your LBS should have replacements, just take in the old ones for comparison. Bearings are cheap.

1. I always use new bearings. Loose bearings cost about 2 cents each if bought in bulk, maybe you will have to pay your shop 5 or 6 cents each, which is nothing. I see a small mark on the spindle. Would need to see an entire 360 degree view before passing judgment. Best bet is to take your bike and these pieces to your favorite LBS and have them replace bearings, grease, and adjust.

"....im having a hard time removing the opposite side of the piece in the top left corner...

You are aware the drive side cup is a LEFT hand thread?

That "slash" mark on the spindle concerns me. Is it a gouge or just grease?

Also note the spindle is not symetrical. One end is a "few" mm longer than the other.

What are the numbers on the spindle.
Likely something like 3-P or 3-S etc. That's a size/length code.

JIS crank , maybe a UNxx cartridge BB can be substituted,
those are a fit and forget thing. :thumb:

See the shiny track on the axle, where the bearings were obviously wearing against it? Check all around that shiny track -- if there's a rough patch anywhere on it, the axle is pitted and needs to be replaced. Same thing on the inside of the cups where the bearings were tracking -- any pitting and the part is shot. Unsure if it's pitting or not? Run a ball point pen around the bearing track -- should be smooth; if you pick up on some roughness, part is pitted.

the markings on the spindle are
5N
84- e

that is a little gouge i guess, the rest of the spindle looks really smooth

The 5N denotes a 70mm shell width.
The bad news- You probably have an Italian spaced BB. (Bianchi makes sense for this duh)

On these, the drive side cup is actually RIGHT HAND threaded, instead of the most common LH thread.
Maybe that's why it doesn't want to come off???

http://sheldonbrown.com/harris/botto...s.html#italian

Clean everthing. If the balls have not lost their shine you can reuse them. Grease the cups, bearings and cones on the axle and put it together. The final adjustmnet should have a slight amount of drag indicating preload. Preload is necessary for the life of the unit. http://www.sheldonbrown.com/brandt/bb-adjust.html

thanks guys, im just going to reassemble it and see how it is.

can you post a few pics of your bike? what model is it? what components.

https://fbcdn-sphotos-a.akamaihd.net...63551608_n.jpg

suntour arx derailleur
the crank just says sakaes

i just put all the stuff back in with some new bearings. would i be able to replace them with a single piece cartridge?

Take your spindle to your LBS and they should be able to order you the correct size.

The most likely reason is as Bill Kapaun said, a right hand thread. These have a habit of unscrewing unless they are screwed on tight; real tight! In fact some have been known to place the fixed side flats in a vice and tighten it using the bike frame as leverage. Best to leave it there if you can..

Yes, although not as retro as a loose ball bottom bracket, the cartridge BB just screws in tight on the right side, and a removable threaded ring that screws on tight on the other. Remember you need to remove the fixed cup that is on now.