Forum home Road cycling forum Workshop

Slipping Force BB30 pre-load adjuster

wishitwasallflatwishitwasallflat Posts: 3,109
edited April 2016 in Workshop
Hi,
Ive recently moved to a frame that uses SRAM Force BB30 cranks and they fit great - BUT - the pre-load adjuster appears to be slipping back on the crank so its loosening off and introducing play. The pre-load adjuster is not unscrewing (the grub screw is tightened to close the gap and is staying tightened) its the whole adjuster unit that is moving (as far as I can see) on the crank shaft towards the NDS crank. After a ride I can slide the whole unit back towards the DS, by a couple of mm and restore the bearing pre-load as it was set.

Like always with this crank set I have a bit of space behind the pre-load adjuster unit (i.e. between the outboard face of the adjuster unit and the inboard face of the NDS crank arm). So far I haven't fitted any spacers in that space because there should be no need for them. If in doubt see - http://www.bikeforums.net/road-cycling/ ... stall.html for some pics and discussion of the spacer issue.

AFAIK the pre-load adjuster is supposed to stay put once it screwed down to pre-load bearings and the grub screw is tightened to stop it unscrewing - problem is mine appears to be slipping back on the axle without unscrewing!

Seems to me there are four possible solutions - would be very grateful if anyone could give any advice on these or alternatives:

1) Get a new SRAM pre-load adjustor and try with it
2) Get another makes pre-load adjustor and try with it
3) Fill that space behind the pre-load adjuster with spacers (looks like 7.5mm would push it in tight and hold
4) Remove the adjuster and replace with a (normal/old style) wavy washer and pack NDS with spacers to half compress it (should take about 7.5mm of spacers plus whatever the difference in width is between the adjuter ring and the half compressed wavy washer).

This is driving me mental so any advice really appreciated!

PS- Yes there is grease on the axle - but - the SRAM fitting instruction say it should be greased and some of the grease from behind the dust caps (stepped washers that fit directly against the outboard face of the bb bearings themselves) squeezes out. Would hate to fit with no grease as that seems crazy on moving parts and bearings so dont consider that a viable option.

Posts

  • sungodsungod Posts: 12,212
    i had an adjuster fail a couple of years ago, it was on an sram red srm bb30, but i think it's the same device

    replaced it and all was ok

    took a bit of searching to find one, i got it from an online store in netherlands, but the website says they are no longer operating

    try sram part number 11.6415.001.000

    edit: of your other options, 4: spacer, then use shims to get the wavy washer almost but not quite flat - downside of this is that it may take a few attempts to get it right
    my bike - faster than god's and twice as shiny
  • sungod wrote:
    i had an adjuster fail a couple of years ago, it was on an sram red srm bb30, but i think it's the same device

    replaced it and all was ok

    took a bit of searching to find one, i got it from an online store in netherlands, but the website says they are no longer operating

    try sram part number 11.6415.001.000

    edit: of your other options, 4: spacer, then use shims to get the wavy washer almost but not quite flat - downside of this is that it may take a few attempts to get it right

    Cheers sungod; I did see your other posts, on other forum, about these cranks and hoped you may have experience and reply. Much appreciated. Think I will take a punt on a replacement (if I can find one) as the trial and error, wavy washer route, seems like way too much work (unless you hit the jackpot quickly!).
  • Just found one from Germany on Amazon so hopefully that will sort me out - thanks again sungod
  • trailflowtrailflow Posts: 1,311
    i recently installed the same crank and had the same issue. i fitted 3 plastic 1mm washers and a wavy washer betwwen the adjuster and bearing cover, which sorted it for me.
  • trailflow wrote:
    i recently installed the same crank and had the same issue. i fitted 3 plastic 1mm washers and a wavy washer betwwen the adjuster and bearing cover, which sorted it for me.

    Brilliant trailflow many thanks for your help. May I ask, did those extra spacers and wavy washer mean there was no free space at all behind the adjuster, so it couldn't slip back (outboard)? Or did they just stop the adjuster moving outboard somehow even though there was space left for it to do so?

    Also, sorry if its cheeky, but I would be eternally grateful if you could possibly post a photo of your NDS spacer arrangement showing where it all goes.
  • sungodsungod Posts: 12,212
    for spacers/wavy washer on the nds, i'd go...

    bearing shield - shim(S) - spacers - wavy washer - crank

    ...i don't think it really matters which way you do it, but this way means you can add the thin shim(s) without taking off the spacers

    the shims are thin, clear plastic, i think they come with the bearings, the spacers don't

    the nominal thickness of the preload adjuster is 6.5 mm, plus the thin metal spacer it comes with - which i'd fit as...

    bearing shield - wavy washer - thin spacer - adjuster
    my bike - faster than god's and twice as shiny
Sign In or Register to comment.