Square taper, grease or not!!!!
- Thread starter dicoverybmw
- Start date
timax
Dirt Disciple
NO Grease on Tapers! Slight spray of Teflon based spray lube (more so on a Ti axle) Just to stave off any cold welding ;-). Grease the thread of the bolt (old school) Put thread lock on the thread of the bolt (new school). The appropriate grease on the thread of the bolt allows it to stretch and the thread to grip! You want the bolt to distort at the correct torque, not the taper on the crank arm! There are different tapers too! the obvious one being NOT to fit Camapag cranks on to Shimano axles!
timax B-)
timax B-)
dicoverybmw
Retrobike Rider
Thanks for all the replies, glad we've cleared that one up then!!!!!!
Still no proper reasons from the NO brigade
Putting a bit of grease helps it it slide on fully and to more importantly slide off again
Grease DOES NOT soften alloy so the axle pushes further into the crank damaging it,as has been suggested a couple of posts back
That comes from people thinking they know what theyre about and use the biggest spanner they have and keep turning it more and more forcing the taper of the axpl in deeper and deeper till the crank has been damaged
Then they blame the grease :roll:
TORQUE
This is what the bloody bolt is for. Take a torque meter and tighten the bolt. DO NOT OVER TIGHTEN
Putting a bit of grease helps it it slide on fully and to more importantly slide off again
Grease DOES NOT soften alloy so the axle pushes further into the crank damaging it,as has been suggested a couple of posts back
That comes from people thinking they know what theyre about and use the biggest spanner they have and keep turning it more and more forcing the taper of the axpl in deeper and deeper till the crank has been damagedThen they blame the grease :roll:
TORQUE
This is what the bloody bolt is for. Take a torque meter and tighten the bolt. DO NOT OVER TIGHTEN
- Feedback
- View
Parktool say NO.
RadNomad
Senior Retro Guru
This is a fundamental engineering assembly question and not specific to bicycles. My father is a retired Royal Air Force propulsion engineer and instructor (piston/jet/gas turbine/bypass turbofan/turboprop you name it) and has always answered every engineering question i ever posed to him with impressive accuracy and detail. Even though i'm a former qualified BMW technician my father has demonstrated countless times over the years [by knowing more than me!] that military technical education is second to none. These guys know what they are talking about. I say this only to provide background and credibility to the following answer which he just emailed me:
"Any component which is required to slide onto a shaft be it splined or keyed must have a clearance between the male and female elements in order to facilitate assembly / removal, thus it falls within the clearance class of fits. However to enable drive torque to be transmitted without play, vibration and damage this clearance must be positively taken up and this can not be achieved by axial loading alone by ( for example a bolt ). High torque applications in sophisticated engineering devices for example aircraft propellers will employ a splined shaft where the hub is clamped between a rear and front cone, the rear cone is often a split phosphor bronze cone slid on to the shaft before the prop is installed. The hub ( propeller retaining ) nut then tightens on to a steel front cone which will locate the hub and compress the rear cone onto the shaft, thus removing all clearance ( this is not an interference fit ). Smaller more precise applications will employ for example a smooth tapered shaft and "Woodrough" key. A cycle crank is a well engineered quick fit and remove variation in that the flats of the square on the shaft will provide location and positioning while the taper will centralise as it eliminates the clearance between the two elements ( crank and shaft ). Any tapered drive will require some mechanical force to "break" the tapered lock on dismantling, this commonly takes the form of an extractor of one form or another, however corrosion or oxidization between the tapered surfaces will impede separation and damage the mating surfaces. Most applications would therefore recommend the use of a thin film of quality impregnated anti-seize grease, such as graphite, molybdenum or copper, due to the nature of machined metal surfaces and the clamping forces involved, metal to metal contact will not be compromised. the components are thus protected from the ingress of atmospheric moisture, water and dust and ease of dismantling is thus ensured".
This agrees with the RaceFace advice which is another reliable engineering source.
"Any component which is required to slide onto a shaft be it splined or keyed must have a clearance between the male and female elements in order to facilitate assembly / removal, thus it falls within the clearance class of fits. However to enable drive torque to be transmitted without play, vibration and damage this clearance must be positively taken up and this can not be achieved by axial loading alone by ( for example a bolt ). High torque applications in sophisticated engineering devices for example aircraft propellers will employ a splined shaft where the hub is clamped between a rear and front cone, the rear cone is often a split phosphor bronze cone slid on to the shaft before the prop is installed. The hub ( propeller retaining ) nut then tightens on to a steel front cone which will locate the hub and compress the rear cone onto the shaft, thus removing all clearance ( this is not an interference fit ). Smaller more precise applications will employ for example a smooth tapered shaft and "Woodrough" key. A cycle crank is a well engineered quick fit and remove variation in that the flats of the square on the shaft will provide location and positioning while the taper will centralise as it eliminates the clearance between the two elements ( crank and shaft ). Any tapered drive will require some mechanical force to "break" the tapered lock on dismantling, this commonly takes the form of an extractor of one form or another, however corrosion or oxidization between the tapered surfaces will impede separation and damage the mating surfaces. Most applications would therefore recommend the use of a thin film of quality impregnated anti-seize grease, such as graphite, molybdenum or copper, due to the nature of machined metal surfaces and the clamping forces involved, metal to metal contact will not be compromised. the components are thus protected from the ingress of atmospheric moisture, water and dust and ease of dismantling is thus ensured".
This agrees with the RaceFace advice which is another reliable engineering source.
RadNomad":1gkx77d6 said:
My dear old Dad was principle engineer for BAeSema(British Aerospace/SEMA division concerning Naval ,aircraft and Subs) and much like yourself could answer ANY engineering question i ever posed to him,be that Nuclear, metallurgy, whatever, you just couldnt pose him a question he couldnt answer
Its too late now of course as he has passed on :cry: but i do wish i had asked him the above question.
in all the time we just never covered it.He did say once that Fishing was a complete and utter waste of time.
