24 replies to this topic

[squonk]

well im hoping for some expert help if you can assist.

 

my old calipers were knackered, so i bought some good second hand ones off here from a carpe member, that have only seen 11000 miles, so

changed calipers tried to bleed system but it wont bleed . had a spare master tried that, tried sucking the air out of the nipple via a pipe (ooh matron) no good still cant get the master to stroke hard enough to push all the air and push pistons out from recesses.

brought brand new master cyl rebuild kit , no change , no better performance than before.

my brother is a very experienced mechanic and has tried evrey trick in the book he knows to bleed. no luck so far

 

one caviat to add here .

 

when we took posesion of the second hand calipers , he wanted to check that the pistons and seals looked good, so he opened them and all was good, so carefully put them back understanding the importance of seals and the function thereof so carefully rebuilt the calipers (no new seals or o rings used as they all looked good ) after the event ( too late) we saw in the manual that it states the calipers must never be parted and maybe it will turn out to be this action that is letting in air preventing us from bleeding.

 

however he is a meticulous bloke and said they went carefully back together, he is certain he didnt disturb the seals or pinch them and says no reason why they shouldnt seal again.

 

 my mate took his tdm ones part and they worked fine afterwards.

 

has anyone got any help or suggestions as to why it wont bleed with two changed masters , new master rebuild kit, braided hoses and calipers in good condition.?

 

anyone offer any bleeding tips when faced with this problem.

 

 my brother has the pistons pushed back in to the recesses as far as they wil go and is going to try and pull them out a far as they would go as in normal position just to try this.

 

changing the caliper O rings and piston seals , will of course be the next step now, but incase this is NOT the problem any experience is gladly welcome of if any of you have faced bleeding brake problems and have overcome it.

thank you

Edited by squonk, 16 October 2014 - 06:54 pm.

[Catteeclan]

Tried the good old shringe on the bleed nipple pushing the fluid backwards?

[dablik]

Was a recent-ish post about buggered bleed nipples !!!! seems odd you cant bleed them both though, have you tried if the brake lines are not blocked ????

[squonk]

thanks guys , tried pushing fluid backwards, just cant shift some air the master piston is plenty good enough to push the air free fluid in its normal use but is too weedy to shift the air blockage.

nipples are in good condition taken out checked and seat fine both sides.

somethings not right here , he took the calipers apart again , reset pistons to out position but nothing but nothing works. same old air trapped somewhere with a master too weak to overcome it and force it out. unlike a car master with big master piston movement , bike master pistons are small with small movement and it cant overcome the air lock. tried sucking , blowing , taken one hose off so it only has to do one caliper , nothing works.

[Gdogg]

squonk please don't think I'm taking the piss coz I'm not but have you got the calipers on the right way up ie bleed nipple at the top of the caliper , I only ask coz went through exactly the same scenario on the 1st rebuild of WinalotPrime, I got through whole bottle of DOT4 fluid and so much bad language before the penny dropped and like a tw##t I'd put the calipers on so the bleed nipple was at the bottom (don't ask !!!!!) swapped them round and 10mins later solid brake lever 

 

Just a thought that's all.

[g650xtdm]

squonk please don't think I'm taking the piss coz I'm not but have you got the calipers on the right way up ie bleed nipple at the top of the caliper , I only ask coz went through exactly the same scenario on the 1st rebuild of WinalotPrime, I got through whole bottle of DOT4 fluid and so much bad language before the penny dropped and like a tw##t I'd put the calipers on so the bleed nipple was at the bottom (don't ask !!!!!) swapped them round and 10mins later solid brake lever 

 

Just a thought that's all.

 

I was replacing calipers on my car once and didn't realize they gave me two right hand calipers, so one of the bleed nipples was pointed down.  Took me an hour or two to realize what was wrong.  Those air bubbles just don't like to go downhill!

[Catteeclan]

How about bleeding the master cylinder first then work the fluid through the pipes then callipers using clamps, unless you're fitted them other pipes.

[squonk]

thanks again guys, for some suggestions, no such thing as a dumb question or response, but yes calipers are on correclty and nipples top position, there is a lot made of that fact actually looking into it on the net and trapped air and the difficulty of removing it is not as uncommon as you think, overcomming it though,is a duel that the air is winning at the moment ! 

its getting near the "box of matches and can of petrol point " now ........... but petrol is not cheap !

 

keep em comming chaps any suggestions or cure gladly welcome

[Bythesea]

It does sound like there is a blockage of some sort, could something have worked it's way into the brake line? Try blowing the lines / calipers through with compressed air if you have a compressor.

 

I've taken the calipers apart before for powder coating and have put them back together with no issues. However it did take me a couple of days before I thought they where good enough.

 

Another trick is to tie the brake lever back to the handlebar and leave it over night with the master cylinder cap off, air bubbles like to travel upwards at night!!!

[squonk]

thank you "by the sea" tried the handlebar cable  tie, and i have used this one before with success and no change with this situation unfortunatley, but thanks all the same

[Gasman]

hi squonk
I sold you the brakes and can confirm that they worked perfectly when I removed them. As I said previously I only changed to upgrade to blue spots.
Tried to PM this but you don't receive them.
Regards
Dave

Edited by Gasman, 17 October 2014 - 08:46 am.

[Studley Ramrod]

I remember having to bleed air out from the master cylinder, by moving the lever ever so slighly, but very frequently, I could see the air bubbles escaping.  Took me a good few hours before I'd got enough pressure to push the pistons.  Kept the master cyl top off and kept topping up. 

[squonk]

well guys GOOD NEWS at last !

 

 got the job done finally, used a variation on a theme of reverse bleeding which wouldnt work first time ,likely due to the lack of pressure we could exert wasnt enough to overwhelm the air , but tried a new theme of a trigger spray unit, one end in brake fluid the other onto the nipple using a pipe connector, it was a long shot but did give a suprising amount of pressure and slowly but surely  worked the air out through the master. it was slow progress but we now have a very good brake lever !

job done !

thank you everyone for all your inputs and i hope that you will all benefit from how these are overcome when they come your way.

this is what forums like this are all about , again thank you.

 

gasman i know the calipers were fine it was just trapped air no aspertions aimed at you my friend , its all good now, so problem over..... aaahhh

[Gasman]

Well done! bet you feel good,
 
 Prof.

I don't know about squonk but I am very relieved.

[Studley Ramrod]

 

All is good !

[dablik]

Woopwoop 

[squonk]

ha ha , yes relieved doesnt even come close !!

it was a nightmare from which i thought there was no escape !

just goes to show though , NEVER GIVE UP !  cry, if you have to, but  NEVER GIVE UP

[Favs]

 

All is good !

Surely should read - Ale is good!