Should every bolt be greased to ensure proper torque?
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  1. #1
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    Should every bolt be greased to ensure proper torque?

    Just got a new specialized bike. I'm making sure everything is torqued to the exact nM specifications (according to the manual). Some of my bolts (faceplate, stem) had some grease on the threads while some others didn't (seatpost collar). Nothing is mentioned anywhere in the manual regarding grease on the threads. If I grease the threads, I understand (correctly?) that for the same 6.2 nM torque measured with my wrench, more pressure will be put on the seatpost, as there would have been less friction on the collar bolt. But would it be the correct torque?

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    1) Grease all the stuff.
    2) Don't overthink your stuff.
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    Cxwrench gets my vote.

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    If you properly use a torque wrench that repeatedly applies torque within the allowable variation of the device you will always be at the correct torque. A greased fastener and a not greased fastener however, will result in a joint with different clamping force when ran down to identical torque. There are reams of studies out there on the relationship between torque and clamping force and I myself have ran down thousands of fasteners of various grades, with various plating types, different combinations of nut types and even different lubrication types (including no lubricant) correlating clamping force with torque.

    Don't put yourself though that (trust me we all should have better things to do), just grease them all like CX said then go for a ride.
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    Should every bolt be greased to ensure proper torque?
    It all depends on how familiar you are with wrenching. I hardly ever use a torque wrench. My stuff stays tight and I don't ever break or strip stuff.
    Grease doesn't ensure proper torque. It could actually cause over torquing if your torque value is a dry torque and you're using grease.
    Grease is used to prevent corrosion, galling, and seized fasteners.

    As craiger mentioned, torque can get very very complicated. Fortunately on your bicycle, it doesn't need to be. There's nothing that critical that you need super precise accuracy. When the manufacturers give a torque value, they've taken into account enough range to allow for people using wet or dry fasteners. There is no correct torque "value". It's not an exact number you need to hit. There's a range of "enough" torque to "too much" torque. You just need to be in that range.

    Grease everything. If you're given a torque range, start with the lower value.
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    .....or loctite for some things. But either will do.
    Apparently a lot of stem makers think loctite is the way to go because they come with it already on the threads, but grease is fine.

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    Quote Originally Posted by Peter P. View Post
    Cxwrench gets my vote.
    And Mine!!!!

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    Quote Originally Posted by cxwrench View Post
    1) Grease all the stuff.
    2) Don't overthink your stuff.
    Bam!

    Somebody, rep cx. I used up all my cx reps.

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    Quote Originally Posted by SPlKE View Post
    I used up all my cx reps.
    I'm willing to trade my reserve of reps if the price is right. I take paypal.

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    Quote Originally Posted by bvber View Post
    I'm willing to trade my reserve of reps if the price is right. I take paypal.
    You must spread some Reputation around before giving it to bvber again.

    Dammit, I'm a reppin' fool. A promiscuous repper.

  11. #11
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    Quote Originally Posted by ToiletSiphon View Post
    Just got a new specialized bike. I'm making sure everything is torqued to the exact nM specifications (according to the manual). Some of my bolts (faceplate, stem) had some grease on the threads while some others didn't (seatpost collar). Nothing is mentioned anywhere in the manual regarding grease on the threads. If I grease the threads, I understand (correctly?) that for the same 6.2 nM torque measured with my wrench, more pressure will be put on the seatpost, as there would have been less friction on the collar bolt. But would it be the correct torque?
    and if you use a torque wrench for small amount of torque, like 4-6 Nm, then you should have them re-calibrate regularly. Else it's better just to go by feel and not over torque things, because I say over-torquing do more damage then under-torquing!

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    Lubrication will result in over torque pressures. Be careful.
    Normal readings rely on the friction from dry components.

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  13. #13
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    i usually grease everything. if it doesn't get grease (or not much grease), it's derailleur cable anchor bolts or skewer threads. square taper spindles get just a tiny amount. brake pad/shoe bolts get little to none.
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    Quote Originally Posted by velo3300 View Post
    Lubrication will result in over torque pressures. Be careful.
    Normal readings rely on the friction from dry components.

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    Not really. Torque is torque and the only thing measuring it relies on is torque.

    Maybe you meant to say; torque recommendations assume dry components?

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    Quote Originally Posted by velo3300 View Post
    Normal readings rely on the friction from dry components.
    Says who? Did you just make that up?

    From Shimano Manual
    • When installing the pedals, apply a small amount of grease to the threads to prevent the pedals from sticking. Use a torque wrench to securely tighten
    the pedals. Tightening torque: 35 - 55 N·m.


    According to the Shimano Torque Chart. Pedals are 35 Nm. The chart does not specify wet or dry.
    https://www.scribd.com/document/3441...rque-Specs-pdf
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    I gave the manual (https://media.specialized.com/suppor...0000097877.pdf) a more thorough reading. Just under the torques table on page 9, there's the following sentence that I somehow missed the first time around :

    "CAUTION (non-pivot bolts) : Ensure all contact surfaces are clean and greased".

    So there's the definitive answer to Specialized torque values...

  17. #17
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    Quote Originally Posted by velo3300 View Post
    Lubrication will result in over torque pressures. Be careful.
    Normal readings rely on the friction from dry components.

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  18. #18
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    Quote Originally Posted by blackfrancois View Post
    i usually grease everything. if it doesn't get grease (or not much grease), it's derailleur cable anchor bolts or skewer threads. square taper spindles get just a tiny amount. brake pad/shoe bolts get little to none.
    That's pretty much exactly what I do.
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    Sorry to have made such a comment but I was only going by information taken from notes supplied by the engineering industry who may know something about the matter as outlined below.*

    My point was that by using the SAME torque load on a lubricated bolt as given for tables for a dry bolt can result in over stress or breakage.

    * When a bolt is lubricated - less torque is required to achieve bolt axial load or tension. Reduction of torques for lubricated vs. dry bolts are indicated in the table below.
    LubricantTorque Reduction*


    LubricantTorque Reduction*(%)
    No lube 0
    Graphite 50 - 55
    White Grease 35 - 45
    SAE 30 oil 35 - 45
    SAE 40 oil 30 - 40

    Example - Reduction of Torque when Bolt is Lubricated

    The maximum tightening torque for a slightly lubricated*1" Grade 5 coarse bolt*is*483 lb ft. Dry bolt torque is approximately 30% higher - or*628 lb ft.
    Tdry*= (483 lb ft) (1 + (30%) / (100%))
    ** =*628*lb ft
    If the bolt is lubricated with SAE 30 oil - the torque compared to a dry bolt is reduced with approximately*40%.
    TSAE30*= (628 lb ft) (1 - (40%) / (100%))
    ** =*377*lb ft
    Note that if torque specified for a dry or slightly oiled bolt torque is applied to a lubricated bolt* - the bolt may*overload and break



    Sorry I was only trying to be helpful, maybe should have known better as a new boy


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  20. #20
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    The torque on a bolt on a bike, is not about the bolt, it's about the BIKE!

    .... .... and oiled bolts don't need much torque.
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  21. #21
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    We know that there is a difference between dry and lubricated fasteners. The bicycle industry bases it's torque ratings on them being lubricated w/ grease. If we need to get more specific I'd say white lithium, most likely w/o any additives like teflon.
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  22. #22
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    Interesting THREAD, nyuck, nyuck, nyuck! Sorry, I just couldn't help myself.

    Seriously, this is an interesting topic that I have wondered about. I have always assumed that torque specs are greased. My shop mechanics seem to grease nearly all threads when I've watched them work.

    As to what it affects, it will increase clamping force for sure. However, there is more than one reason to have torque specs and one I can think of is the shear limit on a particular screw. Correct me if I am wrong, but I would think that grease would allow a screw/bolt/thread to tolerate more torque.
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  23. #23
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    Quote Originally Posted by Lombard View Post
    Correct me if I am wrong, but I would think that grease would allow a screw/bolt/thread to tolerate more torque.
    You are wrong. And that is irrelevant.

    'torque specs' have nothing to do with how much the bolt can tolerate.

  24. #24
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    Quote Originally Posted by Jay Strongbow View Post
    You are wrong. And that is irrelevant.

    'torque specs' have nothing to do with how much the bolt can tolerate.
    OK, I stand corrected. Thinking this over again, it is irrelevant.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

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    Einstien stated 'every thing is relative', I'm going with him.
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