Front brake lever not firm air trapped ?

[Mrg]

Twin disc with a new 5/8 master tried the gentle pumping of the lever and bleed the brakes done about 1/2 liter so far no air bubbles and lever still feels like there's air in there any help would be really welcome

[Grog]

Hello mate;

Sounds like there's still a bit of air in there somewhere - shifting the last bit can be a pain after a full refill. First suggestion would be to pull the lever back to the bar and hold it there with a bungee/tiewrap and leave it overnight - any air in the system should(!) rise to the highest point over time. Once you release the lever the air should then escape into the master cylinder. Here's a link to the HEL website with some other good suggestions:

https://race-lines.co.uk/bleeding/

TTFN Grog

[Mrg]

Cheers grog when you say back to the bar do you mean literally as i have got about 2 inch reserve travel or should I open the bleed nipple to get it all the way back

[marmck]

Pump the lever until its firm then tie lever to the bars , doesn't have to be right to the bars the idea is to put pressure in the system & the valve being open the bubbles should rise over night ,if not repeat . I'm sure this is on YouTube if your still not sure .

[Grog]

^^^^ Wot 'e sed

[Mrg]

Thanks everyone all tied back will let you know the result tomorrow.

[Gray17]

Hi For what its worth, I restored a Suzuki GT750 kettle with twin discs a few years ago, all new seals right through, Despite running nearly a full new tin of Dot 4 fluid though callipers, like you couldnt get the last bit of air trapped out. But using the method described here worked perfect for me, no more spongy lever.
That said I've recently restored my Z900 A4 but its US import so only 1 disc, bled straight away with no sponginess, so may well be the fact theres 2 callipers that makes it more difficult to bleed?
Hope you get it sorted. You def need good brakes in todays traffic!

[BAFF1960]

Hi.
Back bleeding alternating between the bleed nipples works every time.

[Mrg]

Brake now feels much better still feels like a bit of air in there will repeat the process after I have bleed it down again hopefully that will be it.
I do have a issue with the joins after being under pressure all night found all of them are weeping a tiny bit not dripping just a tiny bit of fluid bolts are done up as hard as I dare at the moment putting it down to bad quality washers will replace all and check/clean all the sealing surfaces.

[zed1015]

bolts are done up as hard as I dare at the moment putting it down to bad quality washers will replace all and check/clean all the sealing surfaces.

Make sure the washers are real copper and anneal them before fitting ( heat cherry red and quench in water to flash off the oxide).
New washers are hardened from the stamping process so won't conform until softenend.

[DavidZ1R]

Try unbolting the brake splitter and move it so air can travel back up the line. Can get a little bubble sticking in the splitter.

[weaver]

work your way along the brakes lines giving then a tap to work the air bubbles up to the top

[gray]

When bleeding front brakes I always unbolt the front splitter, disconnect the wires and rotate it 90 degrees clockwise, ( or as much as you can) and hold it there with bungees. That way , the little pocket at the knuckle of the splitter which air could be trapped in, cannot hold airing more so can be bled out

[Mrg]

So I have tied back the lever,bleed it, reverse bleed it,angled it,tapped it, alternated it and shouted at it but still brake feels spongy do have a little reserve travel but not good enough.
As everything has been humanly done can only suspect there's something wrong with the new master cylinder have ordered a small bolt to block the outlet to test it on its own.
Unless anyone has a suggestion?

[Mark Tiller]

i once had to resort to raising the calipers to be the highest point(garage rafters)...ie the master cylinder was lowest.....worked for me