Torque setting for Ultegra crank bolts

"peter.kidwell" <[email protected]> wrote in message
news:<[email protected]>...
> "michael killian" <[email protected]> wrote in message news:[email protected]... Hello, I
> have invented a new and unique bicycle. It has front and rear steering and the rider sits facing
> sideways. Attached is a short description of the balance used to ride this bike.
>
>
> More pictures are available at www.sidewaysbike.com

That is certainly an interesting bike. How about a *good* picture of the bicycle so we can see how
it is constructed (minus rider who obstructs much of the detail in your pictures)? Richard

 

"pixelbrainz" <[email protected]> wrote in message
news:[email protected]...
> Hi
>
> I need the voice of an experienced wrench and it will be much appreciated.
>
> This has been flogged to death I know, but there is some very confusing information floating
> around and I have already paid the price so to speak. I have never mounted a splined crank and am
> a little confused.
>
> However, I have mounted many a tapered crank without any problem ever. I would very, very lightly
> grease the taper and gently tap the crankarm on with a rubber mallet. Then set the bolt around 80
> ftlbs or so, not using the bolt to force the arm on but as a retainer.
>
> Shimano specifies 430 inch pounds (greased) for the torque bolt on a
splined
> Ultegra crank. This is not a lot of tightening. However, when I removed the crank bolts, (on since
> new) they were so tight I thought I would break my allen wrench before the bolt let go. I had to
> use a 1" combo wrench as
a
> cheater. As a matter of fact I destroyed one crankarm, had to heat it to get it off.
>
> I notice that there is a bit of shaved and distorted area now where the crank was forced over the
> splines. Is normal? Once this occurs, do I need to change the torque?
>
> I have read to use everything ranging from 430 inlbs as specified to using an impact wrench. What
> is the acceptable norm for you wrenches out
there?
> I can't believe an impact wrench would be acceptable.
>
> Many thanks PB

According to the Shimano Service Instructions that come with the crankset, the torque specs for the
splined crank are 305~435 in. lbs (25~36.25 ft. lbs) It sounds like the crank bolts on your
crankset were tightened without being aligned with the splines and/or really reefed down beyond
normal torque specs.

I usually tighten my crankbolts to the max spec (35 lbs) and grease the crankbolt, splines on the
BB and the crank, and the inside of the cap that covers the crankbolt. I've never had problems
with the cranks loosening or removing the cranks. An impact wrench is not needed if the
instructions are followed.

 

"Dave Thompson" <[email protected]> wrote in message news:[email protected]...
>
> "pixelbrainz" <[email protected]> wrote in message
> news:[email protected]...
> > Hi
> >
> > I need the voice of an experienced wrench and it will be much
appreciated.
> >
> > This has been flogged to death I know, but there is some very confusing information floating
> > around and I have already paid the price so to
speak.
> > I have never mounted a splined crank and am a little confused.
> >
> > However, I have mounted many a tapered crank without any problem ever.
I
> > would very, very lightly grease the taper and gently tap the crankarm on with a rubber mallet.
> > Then set the bolt around 80 ftlbs or so, not
using
> > the bolt to force the arm on but as a retainer.
> >
> > Shimano specifies 430 inch pounds (greased) for the torque bolt on a
> splined
> > Ultegra crank. This is not a lot of tightening. However, when I
removed
> > the crank bolts, (on since new) they were so tight I thought I would
break
> > my allen wrench before the bolt let go. I had to use a 1" combo wrench
as
> a
> > cheater. As a matter of fact I destroyed one crankarm, had to heat it
to
> > get it off.
> >
> > I notice that there is a bit of shaved and distorted area now where the crank was forced over
> > the splines. Is normal? Once this occurs, do I need to change the torque?
> >
> > I have read to use everything ranging from 430 inlbs as specified to
using
> > an impact wrench. What is the acceptable norm for you wrenches out
> there?
> > I can't believe an impact wrench would be acceptable.
> >
> > Many thanks PB
>
> According to the Shimano Service Instructions that come with the crankset, the torque specs for
> the splined crank are 305~435 in. lbs (25~36.25 ft. lbs) It sounds like the crank bolts on your
> crankset were tightened
without
> being aligned with the splines and/or really reefed down beyond normal torque specs.
>
> I usually tighten my crankbolts to the max spec (35 lbs) and grease the crankbolt, splines on the
> BB and the crank, and the inside of the cap that covers the crankbolt. I've never had problems
> with the cranks loosening or removing the cranks. An impact wrench is not needed if the
> instructions
are
> followed.
>
An addendum: When installing the Octa-Link cranks, remove the crankbolt cap so you can physically
watch the splines line up properly as you start to tighten the crankbolt. There will be a very
slight deformation the first time the cranks are installed, not much. Make sure you have greased the
splines on the BB and crank, the washer that fits underneath the crankbolt, and as I previously
mentioned, the underside of the crankbolt cap. That makes it easier to use the 'self-extracting
feature when removing the crankset.

 

"pixelbrainz" <[email protected]> wrote in message
news:<[email protected]>...

> Shimano specifies 430 inch pounds (greased) for the torque bolt on a splined Ultegra crank. This
> is not a lot of tightening. However, when I removed the crank bolts, (on since new) they were so
> tight I thought I would break my allen wrench before the bolt let go. I had to use a 1" combo
> wrench as a cheater. As a matter of fact I destroyed one crankarm, had to heat it to get it off.
>
> I notice that there is a bit of shaved and distorted area now where the crank was forced over the
> splines. Is normal? Once this occurs, do I need to change the torque?

It sounds like you may have damaged the crank when you installed it. Did you use Shimano's one-key
release system? Because when installing the crank, it's best to remove the cap, to insure that you
are actually engaging the splines properly. When you say you saw a bit of shaved and distorted area
over the splines makes me believe that you forced the crank over the top of the splines.

The torque of 430in-lbs. is correct, but you should grease the bolt, and the axle as well. You
should also grease underneath the cap, and greasing the plastic washer that sits between the bolt
and cap is a good idea as well. The threads of the cap should get a few drops of Loctite 242.

Russell

 

Russell <[email protected]> wrote in message
news:[email protected]...
> "pixelbrainz" <[email protected]> wrote in message
news:<[email protected]>...
>
> > Shimano specifies 430 inch pounds (greased) for the torque bolt on a
splined
> > Ultegra crank. This is not a lot of tightening. However, when I
removed
> > the crank bolts, (on since new) they were so tight I thought I would
break
> > my allen wrench before the bolt let go. I had to use a 1" combo wrench
as a
> > cheater. As a matter of fact I destroyed one crankarm, had to heat it
to
> > get it off.
> >
> > I notice that there is a bit of shaved and distorted area now where the crank was forced over
> > the splines. Is normal? Once this occurs, do I need to change the torque?
>
> It sounds like you may have damaged the crank when you installed it. Did you use Shimano's one-key
> release system? Because when installing the crank, it's best to remove the cap, to insure that you
> are actually engaging the splines properly. When you say you saw a bit of shaved and distorted
> area over the splines makes me believe that you forced the crank over the top of the splines.
>
> The torque of 430in-lbs. is correct, but you should grease the bolt, and the axle as well. You
> should also grease underneath the cap, and greasing the plastic washer that sits between the bolt
> and cap is a good idea as well. The threads of the cap should get a few drops of Loctite 242.
>
> Russell

Thanks for the info guys. This will help.

BTW, I didn't do the original install. I purchased it set up. It was either factory or LBS, not
sure. I'm in a bit of a boil with the way this bike was put together as somebody strongarmed every
part on it. 2 grand for a bike and all screwed up. Butchers!

This is why I posted originally. If I don't know, I ask. I like to have all my ducks in a row before
I tackle something not 100% certain. You folks are a great resource. as I have been out of the
latest technology for awhile.

Thanks PB

 

"pixelbrainz" <[email protected]> wrote in message
news:%[email protected]...
>
> Russell <[email protected]> wrote in message
> news:[email protected]...
> > "pixelbrainz" <[email protected]> wrote in message
> news:<[email protected]>...
> > > get it off.
> > >
> > > I notice that there is a bit of shaved and distorted area now where
the
> > > crank was forced over the splines. Is normal? Once this occurs, do I need to change the
> > > torque?
> >
>
> BTW, I didn't do the original install. I purchased it set up. It was
either
> factory or LBS, not sure. I'm in a bit of a boil with the way this bike
was
> put together as somebody strongarmed every part on it. 2 grand for a bike and all screwed up.
> Butchers!
>
> This is why I posted originally. If I don't know, I ask. I like to have all my ducks in a row
> before I tackle something not 100% certain. You
folks
> are a great resource. as I have been out of the latest technology for awhile.
>
>
> Thanks PB
>
>
I remember seeing a photo afew months ago that was taken to show that some differences existed
between the size of the spline on the Shimano bottom bracket versus the crank. The result was the
shaving and distortion that you are describing. The photo was from a very good source.... Jobst
Brandt, I think.

Do a search for this and you might find that your problem was not the result of LBS work error.

Mike

 

pixie-<< I would very, very lightly grease the taper and gently tap the crankarm on with a rubber
mallet. Then set the bolt around 80 ftlbs or so

Not necesary to crank this high-I have never had a crank come loose, and have always used
35 ft-lbs...

<< Shimano specifies 430 inch pounds (greased) for the torque bolt on a splined Ultegra crank. This
is not a lot of tightening.

It is is you believe shimano-these numbers aren't arbitrary-

<< However, when I removed the crank bolts, (on since new) they were so tight I thought I would
break my allen wrench before the bolt let go.

Not installed correctly then, probably w/o any grease undee the aluminum bolt cap-

<< I notice that there is a bit of shaved and distorted area now where the crank was forced over the
splines. Is normal?

See above-

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

"pixelbrainz" <[email protected]> wrote in message
news:[email protected]...
> I need the voice of an experienced wrench and it will be much appreciated.
>
> This has been flogged to death I know, but there is some very confusing information floating
> around and I have already paid the price so to speak. I have never mounted a splined crank and am
> a little confused.
>
> However, I have mounted many a tapered crank without any problem ever. I would very, very lightly
> grease the taper and gently tap the crankarm on with a rubber mallet. Then set the bolt around 80
> ftlbs or so, not using the bolt to force the arm on but as a retainer.
>
> Shimano specifies 430 inch pounds (greased) for the torque bolt on a
splined
> Ultegra crank. This is not a lot of tightening. However, when I removed the crank bolts, (on since
> new) they were so tight I thought I would break my allen wrench before the bolt let go. I had to
> use a 1" combo wrench as
a
> cheater. As a matter of fact I destroyed one crankarm, had to heat it to get it off.
>
> I notice that there is a bit of shaved and distorted area now where the crank was forced over the
> splines. Is normal? Once this occurs, do I need to change the torque?
>
> I have read to use everything ranging from 430 inlbs as specified to using an impact wrench. What
> is the acceptable norm for you wrenches out
there?
> I can't believe an impact wrench would be acceptable.

When you use a "one-key-release" or "Autex" type allen bolt crank removal system, add oil or grease
inside the cap in addition to the bolt's threads. The force of removal is borne against the inside
lip of the crank cover. A dry bolt doesn't turn easily.

Factories use impact wrenches because they are faster. Some days those wrenches are set high and
some days they are set low. This is below the threshhold of anyone's attention in a bicycle factory.

Let's review the literature: SR-Sakae said 350~400Kcm for a nutted spindle, 200~250Kcm for a
bolted one.

Shimano precisely says 34.3~44.1 Nm and converts that to 305~391inch pounds ( gotta love that "point
one") for regular cranks and 35~50Nm ( 305~435 in) for hollow arms. (Interestingly, they convert
34.3 and 35 Nm both to 305 inches, so you have to wonder about those decimal points)

The oldest crank torque rating I could find is Shimano's 1982 DuraAce Ex (with One Key Release) at
250~350Kcm Their original OctaJoint splined spindle on the Adamas was rated at 300~450Kcm with 14mm
bolts and at 250~350 _for the same arm and spindle_ with One KeyRelease.

Campagnolo currently says 32~38 Nm and 23.6~28 foot pounds (283.2~336 inches). (I never saw a
printed torque rating for crank bolts before about 1980 or so. Campagnolo didn't print a rating
until about 1990)

My impression of all that is that, unlike auto torque recommendations, these numbers seem
capricious, uselessly "precise" yet broad and probably pulled out of thin air. You have to wonder
about a number that's taken to a decimal point with a range of 30%! And when I see the same part
assembled with a 30% change in torque when the _fastener head_ is different, I can't take that
number seriously.

I torque cranks a bit higher than the printed spec because I used to find the occasional loose crank
at printed ratings. Like you, I am in the upper end of the range or slightly past. But I torque to
50Nm or so. You do realize that your 80lbs is double Shimano's rating, right? Lubricating fasteners
means you are transmitting more useful force to the work than you would on a dry thread.

I don't think your "tap with mallet" operation does anything useful. What do you mean by "not using
the bolt to force the arm on but as a retainer"? Are you smacking that arm hard enough to be the
equivalent of 80lbs? I bet not.

When you postulate "thought I would break my allen wrench before the bolt let go" , you should put a
bolt into a scrap spindle in a vise and torque it until something breaks. It takes a lot more than
you think. I once had a mechanic who did break off crank bolt heads but she was stronger than most
people and stopped that after we showed her a torque wrench. It's in the 200+lb range, off the end
of our scale. And the bolt will break before your wrench at any rate.

When you heated the crank you may have changed the crank material. I don't know how hot that was.
But the "shaved" may have been from not quite being lined up when the crank was installed. That's
all too easy with the current Shimano splined system. And that's why we remove the OneKey system
when we install those arms. You just can't easily tell it is on right otherwise.

So in my opinion you had difficulty removing the crank due to a dry crank bolt and cover and should
probably just reinstall the arm with lubricated fasteners (including the cover plates) and not
worry about it.

Shimano suggests lubricating the spline on these arms. (With square taper cranks we're dancing with
the Subject Whose Name Shall Not Be Spoken [or posted]) Damage to cranks is less likely due to
torque absolutely than to repeated installation/removal.
--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971