67tony 

I love this bike, for looks as well as performance, but have recently noticed a bit of an issue.

An almost imperceptible thunking developed, random, and very feint. I could just barely feel it, through my feet. Examining the bottom bracket cups I see a slight scoring on the non-drive side, and believe that is the culprit. Bearings look fine, and re-greasing did not help.

Rivendell offers a setup they name Tange, but it includes a spindle, bearings, and the plastic sleeve...none of which I need. And, their site does not show a pic of the cup faces, and the bearings are in retainers (mine are loose), so that doesn't sound like an exact match.

Could I buy just the cups from somewhere, preferably Tange?
Does anyone make Tange equivalent parts, quality-wise?
Is there a reasonably-priced assembly that would be an acceptable alternative to my original setup?

Size is 122 x 68, 1.37 x 24t

THANKS!

JohnDThompson 

IIRC, Tange made Shimano's bottom brackets. Loose balls are often substituted for retained balls when serviced, but you can use either. The best retainers hold eleven 1/4" balls; the most common hold nine 1/4" balls, but they can be interchanged. As long as the replacement cups are the same thread and close to the same thickness, you should be able to get it to work.

N.B. noises are notoriously difficult to diagnose. "Thunking" can come from many places, not just the bottom bracket. Pedals and freewheel/freehub can also make "thunks" you can feel through your feet. Process of elimination will eventually show you what the problem is.

rccardr 

And that BB is too wide. 113-115-116 would be the correct size.
Any new Shimano 300 series cartridge style BB would give you as good or better service and performance, plus they are easier to install.

guy1138

So right! I always start at the chainring bolts, then the pedals, THEN the BB.

verktyg 

These are great and not too expensive if you can find one:

I bought a number of them a few years ago for under $30.

I hate overhauling BBs. Fix it and forget it!

There are other inexpensive BB cartridges available too.

As far as the clunk goes, it can drive you nuts trying to trace it down. I've had a number of cartridge BBs work loose enough to clunk: Phil and Shimano. Some times the only way to tell is to loosen the cups and re-tighten them.

Real nice IM BTW

verktyg

67tony 

Great replies, thank you all.
I've gone thru the cassette, probably twice, and it's definitely not the pedals or crank bolts.

I'd love to stick with loose balls and new cups, to better stay in the era, but don't want a crappy setup, either.
Looking on the auction site yielded a few possibilities, but I'm no fan of the company.

I know my spindle is 122 mm, and the shell is 68 mm.

Chainline is good, and the Shimano 600 drivetrain is crisp and accurate.

67tony 

Is this a symmetric spindle?

dedhed

Most cartridge BB are symmetrical.

Common replacements are Shimano UN series 54, 55, 26, 300, Tange LN series.

​​​​​​https://www.sheldonbrown.com/bbsize.html

brian3069

I have a set of Shimano 6400 cups, if you're interested.

67tony 

Thanks, Brian...PM sent.

icemilkcoffee 

FWIW Shimano's tech documents call for 116mm spindle for this FC6206 or FC6207 crankset:
https://si.shimano.com/#/en/search/Keyword?name=fc62

67tony 

Very cool documents, thanks for sharing.

I do see that they list a 116 mm spindle for a 68 mm shell.
This continues to puzzle me, since I carefully measured and definitely have a 122 mm spindle in my 68 mm shell.

A seller accepted my offer, and I have two NOS Tange cups being sent to me.
So, I'll use the existing spindle, buy 22 new loose bearings, and take it from there.

rjhammett

Unless you are the original owner of the bike, who knows how many times the bottom bracket has been replaced. I would get the correct size (as defined in tech manuals) for the crankset you are using. 116 to 122 is a big jump in size.

fleslider 

I agree my 87 Master has 116 BB Axle width. with caged bearing so i would say that someone had cracked into the BB before.

67tony 

Evidence abounds...this bike calls for a 116 mm spindle...thanks for the input!
The pics show ample clearance for a shorter spindle, and I'll re-adjust the FD as necessary.

I've always considered this bike original, but now I admit otherwise. It's strange that someone knowledgeable enough to service a bottom bracket would swap out the spindle, and replace it with a longer size, but that's what apparently happened.

I've ordered the cups, which I needed anyway, and will check my parts bins for a possible 116 mm spindle replacement.

67tony 

Re-examining my chainline, I now do see an ever so slight outward angle at the chainring.
I will definitely be switching back to a 116 mm spindle.

You guys are amazing, truly a wealth of knowledge...thanks again for the help!

Fivethumbs

My '86 Ironman with Shimano 600EX 6207 came with a Shimano 3N bottom bracket spindle which is an asymmetrical 119mm spindle. According to Sheldon Brown's bottom bracket database, the symmetrical equivalent spindle is 122mm. It's possible they put different bottom brackets in different bikes at the factory. Maybe when they ran out of one size they just used another.

cstar 

Gorgeous bike you have there. I love a nice Centurion. I've never seen them in this color scheme, boy do I like it. The guards red and white is nice, the magenta and yellow is great, but this is really, really quite nice.

EDIT: Just noticed the color matched leather lacing in your saddle. What a nice touch 👌You sir have great taste

I used to like being able to service a BB and strongly preferred cup and cone to to sealed units. Over time I've developed quite the opposite feeling. Sealed cartridge BB's just basically work forever, and when they break, replacing them is less work than a routine cup and cone repack. Additionally, if a sealed unit cup loosens a bit it usually doesnt ruin your ride, but such is not true on cup and cone.

There are some gorgeous rebuild able sealed units like Phil Wood and it seems like you could rebuild any cartridge unit if you really wanted to. Sorry for going off the rails here a bit lol. Good luck with your project!