Over tightening external bb cups……

Home Forum Bike Forum Over tightening external bb cups……

Viewing 37 posts - 1 through 37 (of 37 total)
  • Over tightening external bb cups……
  • SiB
    Member

    Could over tightening external bb cups be the reason my new bb has got a rythmatic clickety click in sync with the cranks revolving? It was only a cheap shimano bb and half way round first ride the clicking started and got gradually worse.

    I realise a torque wrench is best for job but without one, on a a scale of 1 to 10 where 1 is feather light and 10 is blood vessel bursting tightening, how tight do you tighten yours?

    Premier Icon breadcrumb
    Subscriber

    Just gently nipped up, about a 3, if that.

    Premier Icon wwaswas
    Subscriber

    It’ll be the pre-load on the crank not the BB tightness causing the problem.

    Premier Icon scaredypants
    Subscriber

    unless your BB shell is well wonky AND you tightened the **** out of them, I’m with WW(aW) and it’s something else

    duir
    Member

    A symmetrical click from the crank area (ie once per revolution) is more likely to be a pedal bearing, not the bottom bracket. In my experience it’s very hard to over torque an external bottom bracket.

    mtbtomo
    Member

    Pretty hard to overtighten the cups in the frame. Preload adjuster can be done finger tight and that will be enough.

    SiB
    Member

    Old pedals so good excuse to get another set!

    Preload adjuster…….apologies for asking but is this the big ‘screw thing’ that you tighten once cranks in place on the none drive side?

    Does clicking mean its irreversible damage?

    Premier Icon theotherjonv
    Subscriber

    When I first fitted mine with a torque wrench (after years of doing it ‘by eye’) I was alarmed how tight they were supposed to be. I’d be surprised if you’ve overtightened them by eye

    Premier Icon breadcrumb
    Subscriber

    Ah, I took it as preload.

    I go tight as possible with the cups.

    SiB
    Member

    sorry, ‘screw in thing’ on drive side!

    Premier Icon Scapegoat
    Subscriber

    SiB
    The preload adjuster is the plastic cap on the NDS. Once you’ve replaced the crank arm you only need to tighten it enough to eliminate play in the crank arm which you can feel by tugging or trying to waggle it. As soon as you have eliminated play don’t turn it any more. Tighten the pinch bolts on the crank half a turn at a time until they’re tight, then push the plastic safety latch down flat.
    Over tightening the preload cap puts too much load on the bearings and will kil them pretty quickly.

    Tightening the bearing cups does not affect the bearing load. I’ll see if I’ve got some pics that will help explain it.

    Premier Icon Scapegoat
    Subscriber

    Here you are. This is a 105 roadbike crank, but the principle is the same.
    Tighten the BB cups making sure you have all the spacers in right. Push the crank through and use teh heel of your hand to get it all teh way through.

    Lift up the security tab between the pinchbolts on the end of the NDS crankarm.

    and push onto the splined end of the crank.

    Seat the preload cap in the threads and start it off by hand

    Use the tool (or a 20p piece) to tighten the preload cap

    No more than finger tight, checking for play by rocking the crank arm.

    As soon as you have eliminated all play, and no more, stop tightening!
    Then use a 5mm hex to tighten the pinch bolts half a turn at a time so you don’t overstress one side of the pinch


    Once you’ve tightened the pinchbolts the preload cap cannot affect the preload any more.

    Finally, push the security tab flat.

    _tom_
    Member

    What is this security tab thing all about?! Mines never been pushed flat, always just left it how it is..

    cultsdave
    Member

    I had this once, turned out to be much simpler than the above suggestions. It was the cable from the front mech poking out and catching the crank on every revolution.

    Premier Icon richmars
    Subscriber

    I think the security thing is mostly seen on road bits, but could be wrong now.

    cynic-al
    Member

    Pedal and chainring bolts tight & lubed?

    dantsw13
    Member

    No, Deore & SLX have the black tab too. It looks really flimsy, but it does stop cranks coming loose.

    teasel
    Member

    Nice job with the pics and tips, Scapegoat. Now all you have to do is make sure you don’t tamper with your photo locations…

    🙂

    legend
    Member

    No, Deore & SLX have the black tab too.

    and XT and Saint and…..

    Premier Icon richmars
    Subscriber

    Ok, I haven’t brought a new set recently.

    I had the same and after some head scratching, it turned out to be one of the pedals.

    SiB
    Member

    Scapegoat, thanks alot for comprehensive instructions, the ‘screwy-in-thing’ i described above is the preload cap which I tightened with an 8mm hex to within an inch of its life…….wrong!! Well, I thought that its got to hold the cranks together so best do it up tightly!!

    Still going to get new pedals though!

    As for front derailleur cable end catching on chainring…….c’mon, get with it, its 1 x 10 NW thesed days!

    Thanks all

    bigyinn
    Member

    dantsw13 – Member

    No, Deore & SLX have the black tab too. It looks really flimsy, but it does stop cranks coming loose.
    No it doesnt, its merely an indicator that the crank is located correctly on the axle.
    Theres a small pin in the tab which locates in a small hole in the axle.
    I’ve binned both of mine as I usually forget to flick it out first.

    brakes
    Member

    the preload cap which I tightened with an 8mm hex to within an inch of its life…….wrong!

    oops. did the cranks not feel a bit tight to rotate? hopefully you haven’t crushed the bearing.

    Premier Icon Scapegoat
    Subscriber

    I’m afraid that may be the source of the clicking.

    fozzybear
    Member

    Sadly your clicking will be due to you making the bearing race due to cranking on the preload.
    You won’t stop it and you’ve done permanent damage.
    Need another Bb, sorry..

    bigyinn
    Member

    Personally I’d back off the preload to normal levels and see how it behaves.

    Is it possible to really crank down on the preload adjuster ? Isnt it a plastic piece with a plastic threads ? and a small plastic tool to adjust it ? I only adjust it up just enough to close the gap between l/h crank arm and BB bearing and I find that enough, but I’d have though that if you attacked it with a lot of force that the threads would give up pretty sharpish. Just a thought but never tested the theory as I generally tread very carefully with plastic threads.
    And no I would have thought you could over tighten the outboard BB shells either. They should be in pretty darn tight. Theres a lot of surface area on BB shell threads due to the diameter, so the odds of damaging the threads provided they are aligned and clean would be remote. Probably round out the notches on the outside cup first and that would take some doing too. As with anything that needs a good torque. No point being daft and swinging off a long bar until going purple in the face. Just be sensible, but do it up firmly. Generally tools are designed with the correct lengths handles for the application it was designed for. Which is why 5 mm Allen keys arent a foot long ! IIRC hollowtech BB tool is about 9 inches long ? Just apply a sensible force to that and you should be ok

    hooli
    Member

    swinging off a long bar until going purple in the face

    I do like that description of how tight something should be, finger tight, quite tight or swinging off a long bar until going purple in the face.

    Yep, Feet off the ground torquing is rarely used in any manual 😉

    SiB
    Member

    Thanks for replies, just had a long weekend in Amsterdam so onlty now mustering up the energy to log on to STW!! 😉

    Preload cap on slx cranks on other bike has a plastic cap – hard to overtighten as threads will strip as said by downthemiddle. The preload cap for this post is metal and if iirc they are a set of raceface deus(?) XC cranks. Cranks go on and the preload cap goes on the driveside with 8mm hex…..this is a preload cap, isn’t it???

    Was only a cheap ‘keep me going’ bb so not bothered if damaged.

    Premier Icon wwaswas
    Subscriber

    this is a preload cap, isn’t it???

    no, on race face you use shims to manage the preload – the 8mm cap needs to be done up *really* tight to hold the arm on.

    SiB
    Member

    wwaswas……thanks for that, 8mm cap done up *really* tight as didn’t want to lose cranks!

    So these shims on race face to manage the preload….?? All I do is put cranks on and tighten up 8mm cap, am I missing something?

    So, the clicking noise……..?? I’ll try new pedals, chainring bolts tight.

    Premier Icon wwaswas
    Subscriber

    http://www.raceface.com/installation-instructions/

    as long as you followed the instructions then you should be ok. It’s the elastomer shim on the crank arm that does the preload.

    jamiep
    Member

    My RF driveside chank always works loose. Has just been done up proper man-tight and with loctite so we’ll see how that goes. No clicking noise though

    SiB
    Member

    Thanks wwaswas, hopefully the rubbing of riding shoes on cranks isnt that bad that I cant see the model of cranks!

    Good luck jamie p, seems like you can tighten that one up as tight as you possibly can!

Viewing 37 posts - 1 through 37 (of 37 total)

The topic ‘Over tightening external bb cups……’ is closed to new replies.