Brake bleeding-where am I going wrong?

[rowdy]

Hi peeps, as title suggests I'm having a little trouble bleeding my brake system, I have changed both front calipers with better condition ones.

As I swapped them over quickly lifting the lines up and speedily sticking the banjo bolt in the replacement calipers thus not loosing much fluid I thought it would be fairly straight forward bleeding the air out of the calipers but today is now the third day I have been out trying to get fluid through the system.

The first day I managed to get a little out but not much and the brake lever was still left with little or no resistance and it was getting dark so I decided to call it a day and left the bike over night with the lever tied back to the bar.
Repeated the process the following day and nothing, not even a dribble of fluid this time so tied the brake lever back and left over night again. So back out today for another go and nothing.

So this is my method.
Undo brake fluid reservoir cap, make sure plenty of fluid.
8mm spanner on bleed nipple
Halfords brake bleeding kit on bleed nipple (with non return valve on end of pipe)
hold brake lever in, undo bleed nipple half a turn.
Do up bleed nipple, let brake lever off.
Repeat until cold/p***ed off.

I did try undoing the bleed nipple half a turn and pulling the brake lever on and off for a while at first as it said on the brake bleeding kit but this didn't do anything, it was only until I used the method I have described above that I managed to get a little fluid through but I have since been unable to get any more out and am now getting frustrated, and am wondering where I am going wrong.

[21QUEST]

You got all washers(two each) resent for Banjos at caliper end and all torqued up correctly...correct?


Ben

[21QUEST]

If all I asked about in my previous post, are as they should be, Then Read This


Ben

[rowdy]

Cheers Ben, have all washers where they should be but haven't renewed them, will try bleeding the master cylinder. Just managed to get a little dribble out the caliper again.

[rockster]

have you got the one way valve attached the right way round? It has an arrow pointing in the direction of fluid flow. You should have no problem getting fluid through - it's air you're trying to get rid of. Either that or you've not undone the nipple far enough?

i no the rear caliper has 2 bleed nipples. carnt remember about the front.

i no when i did my front ones i just pumped the the brake lever loads of times till it started to give some resistance. then started with the nipples n lever method.

also do you keep changing sides not just doing 1 caliper.

and i found jiggling and flicking the hosses at there lowest points helped a bit. to get air bubbles out.

and i woulda used new brake fluid if your goin through all that trouble aswell for a few extra quid.

graham

[rowdy]

The valve is part of the bleed kit, so no way of fitting it the wrong way round.
Tried bleeding the mc as suggested Ben, held lever in undone bango bolt slightly and a little fluid started seeping around the bolt with a few bubbles, pumped the lever, done bolt up, pumped lever, repeated process a few times as described, brake lever still no resistance and no fluid seeping out around the banjo bolt any more.
Does pumping the brake lever whilst the banjo bolt is loosened slightly not draw more air into the system?
Was hoping to bleed the new brake fluid through the system Graham but I'm not getting anywhere.

Just re read your bleeding process.....
might be irrelevant but I usually undo the bleed nipple, then squeeze brake lever until fluid come out.
then , with fluid "oozing" and the brake lever at 3/4 closed toward the bar, close the bleed nipple.
then its release brake lever,
open bleed nipple
squeeze brake to 3/4
close nipple
release brake.Once I only get fluid out of bleed nipple,,I do like ging6996 and jiggle the hose up to the top banjo bolts and blleed them,,i.e
undo banjo
squeeze brake
tighten banjo
release brake until only fluid appears,,
then finally check small hose to master reservoir for air by jiggling that...
god,,never typed so much ,,,stiff fingers now

[21QUEST]

Rowdy,

You don't pump the lever with the banjo bolt(master clinder end) cracked open.

Pump the lever it a few times, hold it to bar, then slowly crack the Banjo open. With the lever still held to bar, nip the banjo bolt up...repeat...usually only need a couple of goes or so to get some resistance. Then you can torque Banjo bolt up properly and bleed properly.



Ben

[rowdy]

Ah I did wonder about this but in the link that you kindly put up you say
"crack the banjo bolt open very slowly and just enough to be able to let fluid escape.
*Pump lever a few times, hold to bar, then close up banjo(don't torque up properly yet)*pump lever a few times, hold to bar, open banjo slow and just enough to let fluid escape, then tighten(again, do not torque up properly yet)."
I did wonder about pumping the lever while the banjo was loose but these are the steps that I followed.