XT M785 problem

supafly1982
supafly1982 Posts: 631
edited March 2012 in MTB workshop & tech
Story so far - Building a bike, hoses were to short so had to get new hoses. Shimano crimp hoses on so had to get new banjo's, Struggling to find banjos but on a hunch bought XTR M985 banjo's as both brakesets share same pads etc.

Brakes were sat a coulple of days with not much mineral oil in them.

Fit new hoses to master cylider using shimano olivs and inserts. new hoses same diameter as shimmy hoses.

for thre banjo's ive used the shimano through bolt. New banjo's are slightly thicker and you have to use 2 copper washers to seal banjo to caliper and through bolt head to banjo. I have got this all lined up and is tight with no leaks.

All is bled with no air in the system.

The Problem.
The levers pull all the way to the bars and hardly budge the pistons at all, less than 1mm.

Ive had the caliper at bottom and cylinder vertically above, ive tried flushing the system from both ends. Nothing appears to be leaking and when i check the oil runs through clear with no bubbles.

any idea what ive done...........and dont say broke them :lol:

Its a system that should work, no air, no leaks, so :?: :?: :?: :?:

Comments

  • ricardo_smooth
    ricardo_smooth Posts: 1,281
    am i right in thinking you've gone for SS hoses? these may be the problem as I 100% know shimano's own hoses work and function as they should (i cut my hose too bloody short on the front!). I know shimano use rubber o rings instead of copper washers that sit inside a cutout in the banjo fitting. If the SS banjo is just a square face, it may be pulling air in.

    I had a similar issue with formula brakes and goodridge hoses. Solution was to bin the aftermarket hoses and I had no problems
  • supafly1982
    supafly1982 Posts: 631
    yeah i was thinking the same thing, also im pretty sure the SS hoses have a wider bore diameter, so this could account for lack of pressure, think i might have to cut my losses and buy these chaps

    http://www.chainreactioncycles.com/Mode ... elID=67212

    bit of a sting, but you live and learn, no wonder im effin broke, bikes cost me just about every spare penny i have lol
  • ricardo_smooth
    ricardo_smooth Posts: 1,281
    I don't see much difference between that and http://www.chainreactioncycles.com/Models.aspx?ModelID=14854 tbh?

    Bet you it works just as well.
  • supafly1982
    supafly1982 Posts: 631
    yeah it might do, you would have to use the Xt through bolt, this could be where the problem occours, on the other hand it might fit with no problems
  • ricardo_smooth
    ricardo_smooth Posts: 1,281
    just re-use the bolt that came originally on the caliper with new o rings
  • supafly1982
    supafly1982 Posts: 631
    well thought i would stick this i here to finnish the post off incase there is someone in a similer position.

    I stuck on the shimano hoses, there was bite at and of travel. found this little gold nugget of info and bought the yellow bleed funnel http://www.youtube.com/watch?v=o2c6ezHY ... re=related

    i could not get the rear brake to bleed, so i rebuilt the front and bled it. it was excellent, so what was i doing wrong with the rear?
    The hose and caliper were not verticle enough, i unbolted the caliper and hoses and cable tied it to to a brush shaft
    DSC01388.jpg

    done the bleed as per vid and that was all it was needed to successfuly complete the bleed.
  • ricardo_smooth
    ricardo_smooth Posts: 1,281
    the yellow funnel is not expensive, however if anyone has an old avid bleed kit syringe lying around (or the copy ones on eba etc), this works just like the funnel and saves a few quid if you have no other use for it. Be sure to wash it out thoroughly as it may have traces of DOT fluid in there and you don't want it to mix with the mineral fluid for shimano :)

Categories