Cotter crank play help
 

Attachment 592392
Attachment 592394
Here i have my trusty commuter bike. it has never let me down and it will always get me from A to B. I bought it two years ago and it has been my commuter to work. when i cycled on it for the first time i noticed there was some play in the bottom bracket. the spindle still moves even when the adjustable cup is tightned all the way. the lock ring is only just on and with the slightest turn to the left it falls off.
Ive ignored it for two years but i have deceided it is time to fix it. the amount of play is now effecting the gears.

Attachment 592393

I reckon that the bike has the wrong length of spindle. Tell me what you think. where can i buy a spindle and what information i need? Also is there a N.O.S cottered crank that is available that would suit this bike which is affordable?

Thank you for your time,
Mb277

Probably worn cups, axle cones and bearing balls.
If BB threading is made to a modern (BSA, or even Italian) standard, I'd replace the whole thing with some cartridge bearings and new cranks.

If you don't want to go that route, open it up, clean it, inspect for wear. Bearing ball change is certain IMO, but check for cups and axle cones for wear - they might need replacement as well. Also, new pins for holding cranks in place should be sourced before mounting it all back. As well as some grease.

Why do you think wrong length spindle ? assume you mean axle ? as these are centrered you need to see how much clearance there is between the inner crank ring & the drive side chain stay, its not very clear in the photo, this gap should be about 5.mm, if its over 10.mm could be axle too long, as mentioned above replace all the bearings, cups, maybe the axle if it shows signs of wear, & new cotter pins. At least that way it stays original, if you go for a sealed BB assembly I don't think they are made for cotter pins, so that means changing the whole crank out, very unwise in my opinion.

No, spindle is correct - it spins, whereas an axle does not.

No, the shaft of a bottom bracket that mounts the crank arm is correctly called a "spindle" as it turns with the crank. An "axle" is stationary and the rotating assembly rotates around it as in hub axles.

Now that the semantic are out of the way, I wonder if that bottom bracket is narrower than the bottom bracket shell. Say a 68 mm bb installed in a 70 mm shell. The excessive depth and inadequate lock ring engagement indicate that might be the problem.

OP: If you really need replacement cups or other parts for that crank and bottom bracket, you might post in the "C&V" forum here. Cottered cranks have been obsolete for decades and these people are well versed in their care and feeding.

I'd open it up and take a look. The adjustable cup shouldn't thread in that far so either there is an issue with 1) the bearing balls (too few or too small), 2) the fixed cup has loosened and is working itself out, or 3) you're using a spindle for a 68mm BB in a 70 mm shell (unlikely). The amount of threads exposed on the NDS cotter may mean that it is a replacement, which means that someone had it apart before, which leads to 1) above as the most likely.

It's also possible the adjustable cup was changed at some point to one that was not as deep between the outer cup face and the ball race.

Hello,
Thank you for the response. If I was to replace the parts I would like to keep it original with a 3 piece bottom bracket instead of a cartridge bottom bracket.
If I was to replace it all where can I buy the cones, spindle and other parts needed?
If it is just the wrong bearing size how do I find out the correct size?

Thanks,
Mb277

play in the crank arm to spindle? the cotters are soft steel

Drift Punch & Hammer.. bang on the end without the nut/threads on it then snug up the nut, dont use the nut to pull it tight.

if that does not work get a new cotter.

Buy Bike Stuff at bike Shops.. not Amazon.

Correct bearing size is 1/4 inch, 11 balls on each side. Getting the proper cups, spindle and cotter pins can be complicated. It would be best to get assistance at a local bike shop or co-op. If not the C & V forum will probably have the most people able to help you. I have the knowledge, but not the time right now to explain everything you need to consider. and it's quite a bit to write out and explain. Again, in-person help would be much preferable, and it may be useful to know where you are located.

As mentioned above, finding the exact replacement parts you need might not be the easiest thing...

Bottom bracket cups shouldn't be a problem. Well, except maybe removing the old fixed cup if necessary. Sometimes those can be a bear.

Spindle availability ain't what it used to be since cartridge bottom brackets have been the norm for a few decades. The problem is likely even more acute for cottered spindles. You'll need to get a spindle that's the right overall length for your crankset, the right length between the races, and the right diameter. These types of measurements became more standardized over time, particularly when square taper cranksets ruled the earth, but there were some subtle variations for cottered cranksets.

Since cotter removal is often a destructive process, especially if you don't have access to a cotter press, you may need to source new cotters. You'll want to match the diameter exactly (it varied, largely by country) and find ones whose angle is a close match for your originals. There was a lot of variation, and it was pretty standard practice to file the flats on cotters to get 'em right for a particular crankset.

Personally, on my '72 Peugeot with a cottered crankset, I switched to square taper to avoid a lot of this fuss. I'm still using an older crankset and a traditional adjustable bottom bracket instead of a cartridge to maintain vintage-appropriate appearance, but I have no regrets about ditching cotters.

Looking at your picture, it seems the lockring should have adequate engagement to stay in place when properly tightened. Is it perhaps stripped?

Same thought. Maybe you just need a new lockring.

After a close look at the pic I must disagree. Although the raised adjustment flats make it look like there is enough for engagement, a magnified view shows that the main face of the cup is recessed below the face of the lock ring by 1-2 threads. That is not sufficient engagement, especially as the OP indicates there is still play in the BB. In any case it's irrelevant as there is little doubt that the BB needs to be overhauled ("I've ignored it for two years...the amount of play is now effecting the gears.")

BB shell facing cutter can make it , the frame's BB shell, less wide. It is a special, Expensive, tool ..

I buy my spindles here: https://www.nusshold.info/Products/O...=2441&pageNr=1

Don't know if they ship outside of Switzerland and those spindles fit French/Swiss BBs.

My German is pretty weak (i.e. nearly non-existent) but I looked at that web site and all I saw were square taper spindles, no cottered ones. Perhaps there is a different category I didn't recognize.

The first 3 or 4 are cottered (“keil”).

I went to a local shop that has a reputation for working on older bikes. I got a new crank axle and cotters for my old Motobecane for about $15.
Steve

EDIT: Here's one... can't say if it's the right size: https://www.niagaracycle.com/categor...-55-x-51-x-152

Thanks, the photos are so small and dark it was hard to tell by looking.

Fine detail:- over many years I've collected several maintenance bike books, one was when I was in USA early 1990s another book published by Haynes a well known UK maintenance book publisher, both these have exploded views showing it to be an axle, whereas other books I have don't / so its really not a big issue, like nowadays you put a speedo on your handlebars & call it a cockpit ! times change why worry in my retirement.