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Pressing fit problem

onlytoveyonlytovey Posts: 49
edited September 2010 in MTB workshop & tech
I have a Lapierre Zesty 2009 which came with a shimano press fit bottom bracket which after a year of use had become rough and grinding and prone to the occasional seizure. Looking for a replacement I found the Race Face BB92 pressfit bottom bracket for 41mm diameter BB shells, like those on the Zesty. However, during the replacement opperation the RF one doesn't fit. So I took some measurments and RF BB92 diameter is 41.1mm and my Zesty BB internal diameter is 40.7mm (brilliant): there's a 0.4mm discrepancy which would explain the trouble I've been having.

Does anyone have a suggestion of what I can do to fit the two together or should I look for an alternative BB?

I could get the RF BB cups lathed to remove the excess but would this lead to other problems by removing the anodizing from the cups?

I don't want a Shimano one because the original one was of poor quality and non-serviceable. I wanted something with replaceable cartridge bearings like the RF one. I have seen the one from Enduro Seals which is made using plastic cup and looks good and would have been my first choice had I not seen the RF one.

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • I understand pressfit tolerances should be between .1 > .3 mm

    You could put the BB in the freezer (sandwich bag) cool it down and maybe try again.
    It might just shrink enough to press in?
  • AnonymousAnonymous Posts: 79,667
    lbknuckles wrote:
    I understand pressfit tolerances should be between .1 > .3 mm

    You could put the BB in the freezer (sandwich bag) cool it down and maybe try again.
    It might just shrink enough to press in?
    Tolerances can't be a range. Tolerances are the maximum deviation from perfection.

    Do you mean -0.3mm/+.1mm?
  • Just maintaining the format in which the original post was made.
    Onlytovey refers to a .4 discrepancy, With the contraction associated with cooling the materials it may just fit is the point I was trying to highlight.
    So ..No I dont mean -0.3mm/+.1mm .

    The Oxford dictionary defines Range
    1 the area of variation between upper and lower limits on a particular scale. :roll:
  • AnonymousAnonymous Posts: 79,667
    I still don't follow. At all. Tolerance is the maximum deviation from a perfect design. how can there be a range on that?
  • I was thinking about freezing the BB and possibly warming the BB some hot water/steam before fitting but i was concerned that i might be forcing the fit and stressing the BB which could lead to a failure of the frame and a very unhappy rider.

    As I understand it the cups should be ever so slightly wider than the shell to get a tight fit but is the 0.4mm difference excessive?
  • *AJ**AJ* Posts: 1,080
    I still don't follow. At all. Tolerance is the maximum deviation from a perfect design. how can there be a range on that?

    There can't be a range on tolerance, I think its just bad wording.

    I assume then that the tolerance is 0.3mm...
  • *AJ**AJ* Posts: 1,080
    When you say it doesnt fit how have you tried fitting it?

    Have you used a proper press?....
  • nicklousenicklouse Posts: 50,675 Lives Here
    *AJ* wrote:
    When you say it doesnt fit how have you tried fitting it?

    Have you used a proper press?....

    I was wondering this as well but I was hoping the OP would have looked up the fitting info.
    but id not here is a picture of how to.
    bbt90_460.jpg

    more info

    http://www.parktool.com/repair/readhowto.asp?id=178
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • AnonymousAnonymous Posts: 79,667
    nearly half a mil seems like a large difference for an interference fit, really.
  • Thanks and yes I have seen the correct way/tools to do it, and I was planning on attempting a home made version. However, my initial attempts just to get the cups to rest in the frame weren't successful so I took some measurements and decided not to proceed any further because the difference was larger than expected. So I came here to ask for advice. If the difference between the cups and the shell are typical then that's fine and i'll carry on with the fitting, but if they are larger than normal then I'm going to have a rethink.
  • *AJ**AJ* Posts: 1,080
    Id speak to Raceface....

    [email protected]

    Personally though, I reckon with a proper press itll go in.
  • cheers. i've sent them an email so i'll just wait and see what they say.
  • *AJ* wrote:
    I still don't follow. At all. Tolerance is the maximum deviation from a perfect design. how can there be a range on that?

    There can't be a range on tolerance, I think its just bad wording.

    I assume then that the tolerance is 0.3mm...

    Agreed :oops: bad wording and glad its back on topic!
  • AnonymousAnonymous Posts: 79,667
    I'm still not sure what the actual tolerance was though, which would help us solve this guy's issue! :?
  • onlytovey wrote:
    So I took some measurments and RF BB92 diameter is 41.1mm and my Zesty BB internal diameter is 40.7mm (brilliant): there's a 0.4mm discrepancy which would explain the trouble I've been having

    You nailed it earlier when you commented.......


    nearly half a mil seems like a large difference for an interference fit, really
  • Just to update on this. In the end I ordered a new BB from Real World Cycles - Enduro bearings guys in the states. I decided that it would be a better long term choice since the bearings can be removd/upgraded at a latter date without removing the cups. I was also thinking that there is probably a reason that most press fitt BB's are made from composites rather than aluminium due to the problems with tollerances and press fitting. Anyway I had it fitted by a local shop and so far all is good. its noticably smoother than the one it replaced so happy days. would recommend this as a replacement for all other Lapierre owners. Whilst removing/destroying the shimano one that it replaced I was seriously unimpressed with the lack of sealing, it was full of grit and there are no seals to speak of so no surprise they're getting nakered. I wouldn't do a like for like replacement based on what i've seen.
  • Update:

    Just found this on another forum, it explains why my BB internal diameter was 40.7mm, other Zesty owners should bewary about this. The warranty states that any modifications that are not pre-approved by Lappiere may invalidate the warranty.


    Hi Nickmelon

    I met with Lapierre the other week to discuss several matters including warranties.

    There have been two issues in total with Zesty. mainly in 09 the problem was undersized BBs in the frame. As the cutter weared down it actually reduced the hole made for the BB. Once the BB was 'pushed' in it forced the material to crack around the BB.

    THis was identified and the tool replaced, solving the problem.

    THe main problem in 2010 was the cracking or rear carbon chain stays near the pivot. Surprisingly this was not caused by weak or faulty carbon but by an over zealous machinist taking too much material off when the pivot faces were CNCed. This only happened to a few chainstays but once tightened up across the pivot, they cracked. Ironically it had nothing to do with the pivot action of the chainstay and no matter how hard or gentile the use it would have still cracked.

    Remember this rear carbon chainstay was used on the Spicy 916 which is designed to be a far more agressive animal than the Zesty and very surprisingly had no known cracking!

    Luck of the draw! Hopefully now Lapierre have learnt this error then moving forward 2011 should be relatively trouble free.

    To date Lapierre have been slow to compile data from warranties and learn from trends emerging. Hopefully after all this bad press surrounding a few incidents they will be more 'on the ball' in future.

    The facts remain, more people are riding Spicys and Zestys at enormous pleasure than the few who have had a problem.

    People who have had a problem seek out forums to express their displeasure, the rest of us are out there, riding trouble free, and whos actions speak louder than words!


    thanks
  • AnonymousAnonymous Posts: 79,667
    Holy sweet mary mother of satan.
    It's all very good coming clean about their faults, but man alive, I have just lost ALL faith in their manufacturing knowledge.
  • andyrmandyrm Posts: 550
    Holy sweet mary mother of satan.
    It's all very good coming clean about their faults, but man alive, I have just lost ALL faith in their manufacturing knowledge.

    This. Unbelievable that they aren't keeping an eye on tool wear and that their machinists aren't working to tolerance and checking completed items.
  • AnonymousAnonymous Posts: 79,667
    And yet you'll still get people people are actually proud of owning something that isn't made by Giant or Merida, but by a small player :roll:
  • WOW, I'm honestly shocked that a manufacturer like Lapierre don't have the quality controls to deal with this. Whether internal or externally made, procedures should have be in place. Let's face it (no pun intended) tool wear in CNC is fundamental to pricing and quality control of a manufactured item. If they don't have a system to flag up a change of tooling, what else have they missed or can't be bothered with?
    CAAD9
    Kona Jake the Snake
    Merlin Malt 4
  • AnonymousAnonymous Posts: 79,667
    I know that at least some modern CNC machines can even take tool wear into account, if they've been programmed correctly.
  • andyrmandyrm Posts: 550
    WOW, I'm honestly shocked that a manufacturer like Lapierre don't have the quality controls to deal with this. Whether internal or externally made, procedures should have be in place. Let's face it (no pun intended) tool wear in CNC is fundamental to pricing and quality control of a manufactured item. If they don't have a system to flag up a change of tooling, what else have they missed or can't be bothered with?

    Absolutely. Tool wear is something that can easily be calculated and cutting tools reknifed/replaced after so many cycles. To not have this kind of process and any form of post-manufacturing QC to check for tolerances on the cuts (even a random batch sample) is pretty unforgivable really.
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