brake bleeding probs

[Tempo]

Hey guys,
So im trying to bleed my new brake setup and its basically giving me the shits. I have bled a fair bit of fluid through, not seeing any bubbles. But the pistons are moving in and out slowly (takes about 5 seconds to grab and the same to release from the rotor) and the lever will still pull in all the way if you hold it.
Is this a sign of air still in the system somewhere? I have bled the master cylinder first then the caliper. I have also put thread tape over the nipple threads as I was sucking air in through there. Any ideas or anyone willing to lend a hand?
Cheers.

[Neil-51]

You seem to be doing all the right things. The only thing I can suggest is to leave it overnight for any air bubbles to settle and collect in one place, then bleed again.

[SomeBloke]

I had trouble bleeding mine the other day. If you are taking fluid from master to caliper (fluid direction) because the caliper is below the master you are trying to pull air down, and it naturally wants to go up.

I removed the calipers and placed them above the master and left it overnight. The next morning, a bit of air came out the caliper and I then had a solid bleed.

[agrid]

I usually pump a few times, hold pressure and crack the bleeder so fluid really quirts out, I think it helps move the bubbles, lock the bleeder before releasing the lever and repeat. Put a tube over the bleeder and into a jar after you have the ring spanner on so you don't make a mess.

[Tempo]

Yeh done that a fair few times. The fliud rises in the master when I push the pistons in but once I get it on the rotor I can slowly pull the lever all the way in. Dunno how something so simple turns into a nightmare lol

- - - Updated - - -

Yeh done that a fair few times. The fliud rises in the master when I push the pistons in but once I get it on the rotor I can slowly pull the lever all the way in. Dunno how something so simple turns into a nightmare lol

[Mattis]

It sounds like there is still air in the system to me.

Have you tried drawing the fluid through with a syringe or via some form of vacuum down at the caliper side, once you've removed any component from the mastercylinder side of things I've found you always need to draw fluid back through via vacuum (bleeding just via the lever doesnt seem to help)? Are there any signs of brake fluid leaks, especially around the banjo bolts (which could point to air leaks)? Did all the crush washers go back on either side of the banjo's?

Maybe give the old "cable-tie-lever-to-grip-leave-overnight" trick a go and then crack the bleed nipple in the morning.

Bleeding brakes can definitely be a PITA at times

[Tempo]

I have left the lever tied up over night twice now and then bled it, same thing..
I will try the syringe from the bottom, do you have the lever pulled in for this too?
All the washers seem fine as there all new, I can however see some small fliud/bubbles coming from the rubber around where the lever pushes the master cyl in. Not sure if that's supposed to be sealed without me pulling stuff apart, or if its fliud ive spilt on there in the process? Its all new gear though that's the thing.

[Mattis]

Hmm, master cylinder piston seals might be gone if fluid continues to come out of that location. I'd give that area a good wipe over and then work the lever in and out a few times whilst watching that area to see if any fluid becomes visible again.

It's not a difficult job to replace those seals, remove the lever, there's a rubber dust seal that just pulls out usually, then undo the adjustment lever/bolt out then usually just a circlip to pop out and the whole piston will slide out of the bore. Check the seals first - there could just be some dirt trapped between the seal and the bore that's causing the leak if you're lucky.

In regards to the syringe method - you can get one of these from Supercheap in the oil accesories area (near the funnels etc), it's primarily designed for accurately measuring small amounts of oil for two stroke mixing, forks etc. It's about $14 from memory, then you just use that with a length of hose secured over the bleed nipple. Nope, don't need to touch the lever, just apply some suction from the syringe and then crack the bleed nipple to suck fluid through.

[AAA Super Roo Charters]

brakes they can be a prick to bleed

you didnt say if its on or off road

has it single or twin calipers

but if you fitted a new master did you pre bleed it before fitting the hoses on or it will never bleed up

also does the lever have adjustable positions is so adjust it to its stiffest position

i use the syringe method and recycle the fluid till i have the lever feeling to my liking then flush it through with new fluid - iam a tight arse

as for bleeding you can reverse bleed or draw it through but it does take a couple of goes

another trick i found was push the pistons right back into the caliper so as there is less void to fill hence less air space for air to be trapped

good luck and let us know how you go

[Tempo]

No I didn't bleed the MC first, I hooked it all up and bled it together, I may give that a go though.
It is a single 6 piston caliper for supermoto, so mostly on road but its on a crf450r. It has an adjustable lever so I will give these things a go.
Thanks mate.

[Halo_2]

MC bleed first

[AAA Super Roo Charters]

MC bleed first

how would you do this as ive never done a dry system before

[Halo_2]

With a vizibleed brake & clutch bleeder (supercheap) and bleed MC like you would with just a clear hose (open and close bleeder) to the point you have fluid coming out then because vizibleed is a one way valve just open the bleed valve and pump away till there’s no air bubbles then do the same with the calipers.


Job Done

[Falcore]

Quickly tap the brake lever repeatedly ( doesn't have to be full stroke). Literally just tap it quickly and constantly for a bit.

Doing this has numerous times gotten bubbles to release out of the master cylinder draw point ( for lack of better words) and come to the top of the reservoir.