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Discussion in 'The Shop' started by bomberz1qr20, Dec 10, 2001.
On a square taper BB, does one grease the faces of the taper? Why? Why not?
hey, i don't do it on my own rigs, so i vote no
yeah grease em, it stops em creaking. as well as preventing metal fatigue from direct contact.
I can't believe you guys even consider greasing them!
molybdenum disulfide-based grease.
any mechanic worth his carbon knows this....a little grease never hurts.....D
Not in this case. The taper on a BB spindle and crank is a press fit mechanism. The friction between the crank arm and the spindle causes the arm to slide on so far for a given amount of torque on the crank bolt. If you grease the spindle, the crank arm can slide farther onto the spindle, farther than it was designed to. The result is that the taper on the spindle forces the taper on the crank to expand. Multiple installations like this will cause the crank to move closer and closer to the BB shell, altering chainline and eventually ruining the crank when you pull the spindle all the way through the arm.
It's a poor design... I know, but I still think a little grease is ok and a torque wrench is mandatory so you don't over tighten and cause the problem you mention above.....D
It used to be that this was a dry fit. No grease at all. But current thinking is for a t-h-i-n layer in there. I believe in the old days it was believed that greased tapers would allow the crank arm to be driven on too far and be damaged. Kept up over the number of bb overhauls needed in those days and the crank hole would be so big that the bolt would bottom out. Today you get torque settings so this won't happen and materials are better than then. Better yet go splined, grease the thing well and don't worry about it.
Never ANY grease, ever!!!!!!! It will allow the crack arm to slide up the taper too easily. Allowing you to bottom the bolt out. I have never had my cranks creaking from not using grease.
Actually, greasing anything will afffect torque readings. You will get different readings on greased and dry bolts, too. I have checked the Barnett's and Sutherland's manuals as well as the Campy book at work and they all say no grease. I can't think of any more reliable source than that.
The CRACK arm? I don't grease my crack pipe cause it tastes funny. I don't know about a crack arm, though. I don't put grease in the meth\crank, either. It tends to make the lab more explosion friendly.
Race face recommend grease and I think Shimano now too, but not much. In the past I always cleaned the spindle and the hole. But now I use a very thin aplication. I never had creaking either but its what they recommend.
Id hafta agree with oldfart on this one. pat gauss always says follow the dealer manual, same thing goes for cranks. if raceface designed your stuff and says you should greeeese em' i say grease em.
Race Face recommends it on square tapers? Or on ISIS? I couldn't find tech info on either site, and I have no literature or install manuals for Race Face or Shimano stuff.
Where did you get this info?
Sorry, I'm a total dummbass!
I found it!
From the Race Face tech .pdf:
"NOTE: WE RECOMMEND APPLYING A FILM OF
WATERPROOF GREASE TO THE BB SPINDLE
FLATS BEFORE INSTALLING RACE FACE CRANKS
TO HELP PREVENT CORROSION THAT CAN
OCCUR BETWEEN THE CRANK TAPERS AND THE
BB SPINDLE. This corrosion occurs due to the
natural movement between the two parts and can
adversely affect the life of the crank arm. While this is
a controversial area , our extensive lab testing has
proven that greasing the spindle flats does not
adversely affect the crank arms, while preventing
corrosion has definite benefits. Cranks tend to "suck-on"
to a greased spindle approximately 0.5mm
(0.020") further than they would onto a dry spindle
using the same torque value (28 ft/lbs. max.) on the
crank bolt. We have taken this into consideration in
the CNC machining of our tapers to ensure it is not a
Lubricating the spindle flats is especially important
when using a non-plated steel BB spindle (Shimano
UN52) or a Titanium BB spindle, as corrosion attack
is much worse in these cases."
Well I guess it might be ok on Race Face products, if they have actually compensated for it in their machining, but I still stand with the no-grease theory elswhere, as I doubt any other company takes this into account!
I love learning new stuff!
Been here done that, greased this haven't greased that!
In the Shimano Manual at the shop it recommends NO Grease for square tapers, GREASE is Good for splined!
Just make sure the TORQUE is correct!
Hmmmmmm, Shimano no grease? I have to agree. After all Race Face hasn't been around as long as Shimano, and Shimnao components have had a great history of sucess. I'll stick with no grease.
I've heard this many times. I've worked in shops where the owner made you grease the spendles. I've worked in shops where the owner tell you not to. After 15 years working on bikes I have come to this. If they are brand new cranks and brand new BB you put a very thin layer on the spindle. If they are a used spendle or used BB or both, NO GREESE. Unless you want to sell a new BB or new cranks to your client in the next year.
As old Jim (one of my former employers said) "Greese em I need more sales!"
I grease mine because similar interfaces on machinery are greased and if it caused a problem shimano and all the other companes would have a big warning saying DO NOT GREASE TAPERS stuck to their cranks.
well, i read this thread and the raceface site, and guess what i did saturday.
i put a thin film of grease on the flats of the BB spindle of a RaceFace BB / NorthShore crank interface. The bike was a '98 Turner RFX (Boxxer, MRP, Hope, the works). Then I wiped the grease off, leaving the thinnest of films on all the tapers.
and guess what. when i put everything back together, no more creaking (the guy had brought it in because the crankarms were making so much noise it wasn't even funny. they hadn't been installed properly.)
crankarms were OK, BB was fine, so i stuck a bit of grease in there as i snugged everything back down. everybody's happy, including the guy, who bought a helmet
somebody's going to tell me that i shouldn'tve. I can feel it.
What ? You shouldn't have don that!!!
Way to go man! That's the real way to do it!
I decided to go and give you everyones point of veiw.
Just do what feels right in the situation. I run a Ti spendle and Alloy arms so I use a tiny, weeny bit of ti prep. So thin it's like a jimmy hat.
Anyway who cares at this point.
I had a guy yell at me and a fellow rider one day at the dirt jumps. He called us f****ng idiots. He was right! Untill he said something I hadn't realized that we waisted an hour of good daylight on the merrits and draw backs of ti crank bolt.
Lets all go ride.
Grease em all and let God sort it out!