Tom Keats wrote:
In article ,
writes:
Tom Keats wrote:

smack. Brinelled bearings. specifically unjoyous deployment of
a 4lb hammer when the car's own function can serve the purpose,
and not damage anything.
How come bottom bracket bearing do NOT have this problem when a
hammer is used to drive cotter pins in [1] and out on cranks?
[1] No, tightening is NOT done with the nut with attaching a
cottered crank.
When cotter pins have to be pounded in, there's something horribly
wrong. It usually happens from the bike shop who doesn't quite
have the exact match of what you require, and gives you what they
consider the next closest thing. It's an all too common
occurrence.
Anyway, bearings get ruined by being used dry of grease/lubricant.
I'd like to hear more about that. Who rides with lubricant free BB
bearings?
A number of Pacific Northwesters who frequently ride through deep
puddles and torrential rainfalls, and don't maintain their bikes as
well as they should for the prevailing conditions.
Besides, no matter how you brace the spindle when pounding in
cotters, the shock reaches the ball or two under the spindle. In
You shouldn't have to pound them in. If you have to pound them in,
they don't fit. Maybe tap them in a little, sure -- but to ~pound~
them in?! Nay.
I see you don't work with these. They must be pressed in with
enormous force to give enough preload and insure no "lift-off" from
the small cotter face under hard torque. Those of us who lived
through the steel crank + cotters can recall how they failed with
excess torque if not installed forcefully enough.

I can recall dealing w/ missized/misshaped cotters because
they were all you could get. I also recall occasionally
finding the proper cotters to match the bore.

They must be driven in with a hammer or a special press.

Oh God, that's such a devastation. I just stick well-fitting
cotters in with my thumb.

Not only
that, the also needed to be filed to the right wedge angle to match
the other crank in a one side replacement. The off-the-shelf cotter
not being ready to install. The flat taper was only an indication of
where the flat belonged because the threaded end was offset to pass
under the spindle flat.

You know what's going on here -- you're trying to force the
wrong-sized/wrong-shaped cotters to do the job of the
right ones.

Again, it is a retention nut, not one that
can be used to install the cotter, it having insufficient strength for
that task.

If the cotter pin is the wrong size, of course trying
to tighten it will fsck it up. Trying to get it out
will be even worse.

addition, I saw many cranks secured without more than a 1/2 lb
hammer held under the crank, yet no dents in the spindle resulted.
Of course. The cotters were being smote with a hammer, not the
spindles. I don't think I've ever seen a dented spindle. I've seen
spindles with badly scoured cones, though. Because the bearings
were run dry of lube.
Where do you suppose the reaction force went if not through the
spindle to the bearing cups?

BBs can be done delicatately. Or at least, the violence can
be tightly mitigated. As opposed to stuck handlebar stems.

I still have cottered crank spindles lying around that have no sign
of Brinelling although I have a few head sets where both top and
bottom ball bearings as well a roller bearing ones have fretting
dimples.
In these rainy Pacific Northwest climes, the lower headset bearing
gets the brunt of the weather, especially when unprotected by a
front fender. The cup serves to guide splashed-up water into the
bearing, washing the lube out.
And it's a sneaky effect, because as long as the upper headset
bearing is fine, everything can appear to be good.
I don't think you analyzed the head bearings correctly. If they were
being bathed in water, they would rust solid when parked. On

And yet they generally don't. Go figure.


cheers,
Tom


The manufacturers of steel pinned cranks seem to feel a heavy cast steel
press with 42:1 leverage driven forcefully ( an able man puts out about
80 pounds with both arms just below shoulder height) is a better
approach. That is a humongous amount of pressure.

Here are two clever designs, a VAR #7 crank press and a set of S+S couplers:
http://www.yellowjersey.org/photosfromthepast/VAR07.JPG

When these cranks were still common, even new premium quality Sugino
cranks on Sugino spindles would fail in a day or two of riding when the
assembler neglected to remove, lubricate and press the pins properly.

Although one might get a small amount of pin/spindle contact by drawing
up the nut, the forces at that contact will work it free and deform the
pin's surface in short order if the pin moves at all.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971
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