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So, I shortened the hoses yesterday, and bled the brakes through.
Rear went fine but the front just will not behave. I must have put 150ml of fluid through it but there are still occasional bubbles.
So, I'm sure that the fluid never ran out in the reservoir, and pretty sure that the bleed nipple was always closed, so no air got in there.
That leaves me to conclude that the new insert/olive hasn't sealed, but any suggestions welcomed before I get back to the LBS and replace 'em to try again.
Alex
How does the lever feel?
You can easily check the integrity of the olives by removing the shrouds. If it's pulling air in, it's highly likely that it'll be leaking fluid out.
Wedge something in between the pistons, a little block of wood will do, then remove the MC cap and diaphragm. Pull the lever (and keep squeezing) and watch for bubble coming up from under the silver deflector plate.
Wow, I love this forum, thanks for the prompt reply.
So, "shrouds"? not sure what that bit is, but there's no fluid leaking from the MC-hose joint when I squeeze the brake with a block in the caliper.
If I do this with the reservoir cap off, will I see bubbles under the deflector plate then?
As always, thanks for the advice, always appreciated.
Alex
Hopefully you haven't figured out what the shrouds are and removed them. As well as compressing the olive/barbed insert assembly, the shroud also holds the hose onto the lever/caliper banjo; so if you remove it completely the hose will drop off and you might (read: will definitely) have to bleed again!! My apologies for the misinformation, I'm not sure where my mind was when I suggested removing the shrouds.
Anyway, if the hose fittings are leaking ([url= http://steveukmtb.wordpress.com/hope-braided-hydraulic-brake-hose-assembly/ ]here's[/url] how they go together) then you'll be able to see fluid on the outside of the system. If they're dry, I'd be fairly confident that you can eliminate them as the source of your air bubbles.
OK, so I know what the shroud is, not going to miss that out.
Got a new olive today so will re-fit the hose and see how that goes.
If that's not the problem (and as no fluid is escaping, I don't think it is, where does that leave for air ingress? Around the pistons?
APF
Get a length of rubber hose, a syringe and bleed from the bottom up.
Even a ham-fisted idiot like me has managed to bleed my Minis this way - perfect everytime 8)
Ah, bottom up you say. So, already got syringe et c from bleeding avids and the like, so, just inject oil up through the bleed nipple?
Must be more to it than that...
Alex
Nope, that's pretty much it.
Starting from an empty system :
Quarter of a turn off the bleed nipple and inject the oil up slowly until the reservoir fills (make sure you have the levers horizontal)
Close the nipple and replace the diaphragm - roll it on to avoid trapping air, use an old cloth or rag to catch the overspill and clean up.
Don't think I've missed anything out, I'm sure someone will fill in the blanks if I have.