Nut dents crank?

The right crank on Het Beest, my Nimbus II Muni, creaked when I was out
on the trail and appeared to be somewhat loose. Not having tools with
me, I 1-footed home (in fact I 1.2-footed) and then tried to tighten the
nut but it seemed rock-tight. With wood and a hammer I nevertheless
could hammer the crank further on. I tried again to tighten the nut
using even more force, and it suddenly gave way for a small fraction
(1/24) of a turn. Shoot, what was that?

I undid the nut completely to check the threads etc, and found out that
the nut which has anti-loosen dents on the underside, had deformed the
crank face it has been pressing against for at least half a year. (The
crank should be flat there, shouldn't it?) I tightened the nut once
more, and the last bit went in 1/24 turn increments. I'm not sure if the
nut is fully tight, but I can't overcome any more bumps. Nor do I know
if the loose crank is cured well, haven't ridden Het Beest since.
Pogosticking in the garage alternating with both feet forward, it looked
OK. The crank is a Bicycle Euro 170 mm, the nut may be the one that came
on the Nimbus II or I may have swapped it.

Does this problem sound familiar to anyone?

The pic shows the crank face and the underside of the nut. I haven't
checked the other crank.

Klaas Bil


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Cool. Auto-ratcheting. I don't remember taking off steel cranks but if
the serated nut is harder, as it obviously is in your case, then it's no
surprise that the crank face will be deformed like that. All that
deformation gets sheered off of aluminum cranks when I remove the nut
because it's so soft.


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I think your results are normal. Sounds like your crank is good and
tight!

With alloy cranks, you tend to get more of the aluminum "scraping off"
onto the underside of the nut.


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I've long felt that those serations on the back side of crank nuts do
more harm than good. Of course, the idea of the serations is to act as
a kind of ratchet and prevent the nut from loosening. Maybe they DO
help to keep the nut from loosening on steel cranks (unlikely IMHO) but
they chew up aluminum cranks. I think the serations just add resistance
when tightening the nut - thus preventing the nut from adequately
pushing the crank on to the taper. I've even gone so far as machine off
the serations.

The only real solution is to use the crank installation recipe that John
Childs has written about many times.

Steve Howard


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On Wed, 14 Jan 2004 21:52:08 -0600, showard
m wrote:

The only real solution is to use the crank installation recipe that John
Childs has written about many times.

If I remember correctly, it focuses on hammering the cranks on rather
than tightening the nut to get them on? That's basically what I do.

Klaas Bil - Newsgroup Addict
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I have a feeling you might need two points of contact with the ground for such a thing to work? Or at least training wheels on the front and rear. - John Foss commenting on a picture of a one-wheeled vehicle he saw on RSU.

Klaas Bil wrote:
*suddenly gave way for a small fraction (1/24) of a turn. *


Confess, Klaas; you did not feel that it was 1/24 of a turn, but you
counted the dents ;-)

But even if the nut marked the crank: Shouldn't the crank stay where it
is when properly hammered on? Hm.

Regards,
Juergen


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Klaas Bil wrote:
*On Wed, 14 Jan 2004 21:52:08 -0600, showard
m wrote:

The only real solution is to use the crank installation recipe that

John Childs has written about many times.

If I remember correctly, it focuses on hammering the cranks on rather
than tightening the nut to get them on? That's basically what I do.

Klaas Bil - Newsgroup Addict *

Put grease on the taper. Use a big C-clamp (bar clamp) named Bessey to
press the cranks on. Then use red Loctite on the retaining nut
threads.

The Loctite is the important bit. I would suspect that with the Loctite
you could file off the scallops on the retaining nut. The Loctite would
keep the retaining nut from working loose. That would keep the scallops
from digging in to the crank like that.


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i like the feeling you get from those on a steel crank arm while
torquing down that final time.

thump thump thump.....


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juergen_brauckmann wrote:
*Confess, Klaas; you did not feel that it was 1/24 of a turn, but you
counted the dents ;-)*
Of course. In fact, "as soon as" the wrench lost its 'resistance', I
stopped pushing it so it felt almost the same as if the wrench had
slipped on the nut (which is 1/6 turn).

*But even if the nut marked the crank: Shouldn't the crank stay where
it is when properly hammered on? Hm.
*
No, the hammering on puts the crank at the right position, but the nut
is supposed to keep it there. However, if the dents on nut and crank are
too high, the tops of the nut will be in the valleys of the crank. And
that may not be tight enough.


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john_childs wrote:
*The Loctite is the important bit.*
Of course, how could I forget? A recipe by John Childs always contains
loctite, just as some other people's recipes always contain pepper (or
something else). :-)

Loctite, a universal spice...


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