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headset bearings keep coming loose

ktuludaysktuludays Posts: 86
edited November 2015 in Workshop
Hi Guys

Changed my bearings this weekend for new as had a bit of judder under braking. i have had to retighten them a couple of times this year.
Bottom bearing was shot and replaced like for like.

These are what i fitted:
http://www.jejamescycles.co.uk/kinetic-headset-bicycle-bearing-1-1-8-mh-p08h8-id84125.html

i measured the old and they are exactly the same.

After i fitted them i made sure they were tight but not overly so and then torqued the stem bolts. After 13 miles yesterday i started to get the judder again. i stopped and retightened the headset but upon returning home i noticed that there is a gap top and bottom of the headset.

It wasn't there before as i have pics of the bike when i bought it, so what could be amiss here?
Top
IMG_20151025_140030214_HDR.jpg

Bottom
IMG_20151025_140113905.jpg

Any ideas. All looks ok when i strip it and i rebuilt it as it came off.

Posts

  • keezxkeezx Posts: 1,314
    Is there an expander or starnut in the steerer tube?
    The first is always notorious of coming loose.
    Further check if the topcap does not rest on the steerer when tightened.
    Gaps look OK to me.
  • sungodsungod Posts: 13,346
    most probable cause is that the stem is slipping on the steerer

    less likely...
    steerer and/or stem damaged
    head tube and/or bearings and/or spacers are getting shorter

    the top cap and expander are only there to preload the bearings before you tighten the stem, once the stem is tight they have nothing to do in that respect (ok, the bung may give the steerer a bit of support against stem clamping force, but that's a sideline)

    so, remove stem, clean clamping surfaces of stem/steerer of any grease/dirt/whatever, refit, preload (1 to 2Nm is enough on the topcap screw), clamp enough that it doesn't slip, ride
    my bike - faster than god's and twice as shiny
  • sungodsungod Posts: 13,346
    assuming you are using the correct parts and they are fitted correctly, most probable cause is that the stem is slipping on the steerer

    less likely...
    steerer and/or stem damaged
    head tube and/or bearings and/or spacers are getting shorter

    the top cap and expander are only there to preload the bearings before you tighten the stem, once the stem is tight they have nothing to do in that respect (ok, the bung may give the steerer a bit of support against stem clamping force, but that's a sideline)

    so, remove stem, clean clamping surfaces of stem/steerer of any grease/dirt/whatever, refit, preload (1 to 2Nm is enough on the topcap screw), clamp enough that it doesn't slip, ride
    my bike - faster than god's and twice as shiny
  • cyclecliniccycleclinic Posts: 6,865
    There must be 3 mm between the top of the stem and the top of the steerer. Any less and you can't tension the headset securely and it work loose as you have described.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • Thanks guys. There is def 3mm or more above stem. On the expander nut how far down do I screw the top cap? I set it to approx mid point on the thread then tightened.
  • jermasjermas Posts: 484
    Another possibility- Are you sure the bearing is the same? They can be the same dimensions but, have different chamfer angles (36x45 or 45x45). If thats the case the bottom bearing never seats correctly and can cause the symptoms you describe.
  • keef66keef66 Posts: 13,123
    Thanks guys. There is def 3mm or more above stem. On the expander nut how far down do I screw the top cap? I set it to approx mid point on the thread then tightened.

    Just to be clear, the top of the steerer tube needs to be at least 3mm below top of the stem if there are no spacers above it, or 3mm below the top of the upper spacer if there are.

    And the expander bung needs to be fully tightened inside the steerer so it won't slide up as you tighten the top cap.

    With the stem clamp bolts undone you just tighten the nut in the top cap enough to eliminate any play in the headset. This isn't very tight at all. Check for play by holding the front brake on and trying to rock the bike back and forth; you'll feel knocking if it's still loose. Once you've eliminated play you tighten the stem clamp bolts alternately / progressively. Once the stem is clamping the steerer you could if you wanted remove the top cap, bolt and expander bung; it is not serving any useful purpose any more - apart from keeping rain out of the steerer.

    If your headset is loosening it can only be that the stem is slipping up the steerer.
  • jermasjermas Posts: 484
    Once the stem is clamping the steerer you could if you wanted remove the top cap, bolt and expander bung; it is not serving any useful purpose any more - apart from keeping rain out of the steerer.

    Not quite true, It stops a carbon steerer from being crushed when the stem is tightened.
  • AnonymousAnonymous Posts: 79,692
    Another possibility- Are you sure the bearing is the same? They can be the same dimensions but, have different chamfer angles (36x45 or 45x45). If thats the case the bottom bearing never seats correctly and can cause the symptoms you describe.

    This could be the most likely reason. I recently changed over the headset on my winter bike,a Bianchi Via Nirone.

    The headset that was originally fit is no longer made so I got the closest to the original which was an FSA No.8B Orbit. I tried to fit the whole headset complete but it created the same symptoms mentioned. I eventually only changed the actual bearing and kept the origianal seals and star fangled nut in the fork. Problem solved. I couldn't even use the new top cap as it was a lot flatter than the original and thefore didnt have the 3mm gap as required.
  • jgsijgsi Posts: 5,027
    This is a nice summary of the various headset configurations
    http://www.parktool.com/blog/repair-help/headset-standards#article-section-7
    get yourself a Vernier - well worth the money and measure your orginal bearings as I reckon you have mismatched the bearings along the line.
    Riding along with a dodgy headset in any season aint recommended.
  • I have a vernier and i'm sure they're same as the ones i took out. the depth, OD and ID is the same. One thing i have just noticed is that i checked the external angle which was 45 but i didn't check the internal chamfer.

    I'm gonna have to strip it to check as it could be that giving me the grief. I'll post back when i get to it.

    currently riding the winter hack,old holdsworth steelie, and boy i'd forgot how heavy it was!
  • The issue is the internal chamfer/angle. although the bearings do fit there is a small difference so i'm guessing they are probably a different inner angle.

    bearings side on:
    IMG_20151030_173404354.jpg
    IMG_20151030_173342702.jpg

    See pics if i put the collar into the new bearing it sits higher into the bearing which is where the gaps appeared.
    IMG_20151030_173636089.jpg

    Old
    IMG_20151030_173554938.jpg

    So from what i can work out i have:
    1-1/8" Diameter Bearing
    Internal Dia: 30.5mm
    External Dia: 41.8mm
    Depth: 8mm
    Chamfer: 45 / 45 Degrees one of these is wrong.

    i'm guessing i need a 36/45 bearing with the other measurements the same. Just done some searching on the net and it would appear that a 36/45 bearing in 8mm is not a common thing so could it be 45/45 - how i could check these angles?

    Also see pic of top cap removed - is this is enough of a gap to give good tension?
    IMG_20151030_172748754.jpg

    where do i set top cap on threads before fitting
    at top:
    IMG_20151030_172708749.jpg

    or at bottom of thread:
    IMG_20151030_172726978.jpg

    cheers in advance
  • keezxkeezx Posts: 1,314
    [quote="ktuludays

    Also see pic of top cap removed - is this is enough of a gap to give good tension?
    IMG_20151030_172748754.jpg

    [/quote]

    With that steerer you need at least a 10 mm spacer on the stem> problem found.
  • [quote="ktuludays

    Also see pic of top cap removed - is this is enough of a gap to give good tension?
    IMG_20151030_172748754.jpg

    With that steerer you need at least a 10 mm spacer on the stem> problem found.[/quote]

    Hi. There is a 10mm spacer I just haven't shown it.
  • From the pictures the bearing looks OK.
    You may need more than a 10mm spacer on top of that stem.
    It depends on how the topcap fits as some go slightly inside of the steerer.

    Do you know how to fit that top cap?

    That is an expander and topcap in one setup.
    Set the cap on 3 or so turns and then tighten up the smaller diameter allen key deep inside to expand the collars. Once this is tight use the larger allen key to fit the very top cap and set the preload.
    Then as said before, hold the front brake on and rock bike back and forth, if there is movement or a knocking noise, tighten until it disappears. A good way to do this is to put a finger accros the headset join and feel for motion.
    If you cannot remove the movement then you need to place another small spacer under or above the stem to create a bigger range of movement for the topcap to set the preload.

    Expect a small amount of settling after the first couple of rides, so check and readjust as necessary.
  • jermasjermas Posts: 484
    I'd suggest if your old top bearing is still serviceable, refit it as the lower bearing ( you know it's a correct fit). The lower bearing takes most of the load so needs to be correct. Use the new bearing on the upper-the fit isn't as crucial.

    Fitting the bung- ensure there's no grease inside the steerer.
    Place the top cap only a few turns on the thread-to ensure it doesn't bottom out.
    After stem is in position with top spacer-insert bung.
    Tighten the inner bolt on the bung using a small hex (4MM ?) passed through the top cap.
    Adjust top cap using larger hex (only enough to remove play)
    Tighten stem.

    Basically as above ^^
  • thanks for all the help guys. had to buy a new FSA headset from wiggle on sale at £14.99 to get the right bearings. changed the crown race and all fitted lovely now.

    one thing i have learned is that the top cap has a hex fitting for tightening, i never knew that was there!
  • OuijaOuija Posts: 1,386
    thanks for all the help guys. had to buy a new FSA headset from wiggle on sale at £14.99 to get the right bearings. changed the crown race and all fitted lovely now.

    one thing i have learned is that the top cap has a hex fitting for tightening, i never knew that was there!

    Very few people do. They assume tightening the top cap expands the bung when all that does is drag the bung up to the top cap (at which point the bung will expand a little, but isn't applying any preload to the bearings). Judging by the number of comments on forums like this and in reviews on retail sites like ChainReaction it appears to be a common misconception.
  • Typically it is the stem slipping onto the steerer. I found that carbon paste and the likes don't help. You need a stemp with a better clamp. Cheap stems work for metal steerer but don't work for carbon ones.
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