brake bleeding syringe method stil spongy advise pls

[lukemillar]

Dot5 or dot 5.1?

I was always told it was a bad idea to use dot 5 in a dot 4 system. I guess if you replace the seals and flush the system well, then it would be ok, but for the masses who might read this and run out and buy some dot 5, it is recommended to use dot 5.1 if changing from dot 4.

[V4beermonster]

DOT5

[V4beermonster]

It is fine to use just have to flush system and make sure it is fully bled, I do loads of brake systems for the Suzuki gt750 see here http://www.ebay.co.uk/itm/suzuki-gt750- ... _500wt_922

[oldgreyandslow]

Iwith pipes disconnected from M/c pull brake lever and then put finger over the hole where pipes attach, release brake lever, do this over again until fluid is coming out the M/c then attach lines and bleed the normal way. Priming the M/c removes any air from the union and lines which are real pigs to get out otherwise. Also it may be needed to rest the fluid for 24 hours as you get little air bubbles, resting lets these join into bigger air bubbles. I only use DOT5 brake fluid in my bikes it is more expensive but has a musc higher boiling point, not hydrosorbic and best of all does not strip paint,

I cracked the top bolt on the M/C tied the lever back overnight and this morning I could turn the wheel with the lever fully back, so I pumped the lever and tied it back again. Do you reckon I should start afresh and prime the M/C as suggested and then bleed normally?

Also when the brakes are off when I spin the wheel there's a slight dragging of the pads on the discs, not binding but definetly dragging, not sure if this is related to the bleeding problems or a slight drag is OK?

I used DOT 5.1 fluid

[arsey30]

Don't crack the union and tie back the lever or you will loose pressure and fluid.
Crack the union and pump lever a few times to bleed in the normal way, watching for air bubbles in the fluid as it squeezes out. Tighten bolt back up
Bleeding in this way is similar to priming as you expell the air from the top of the hose.

Now tie back the lever, assuming you have some brake [half a lever travel] so that the system is under pressure

Often the pads rub a little with brakes off if they have been worked on/disturbed, but improve when bedded in.

You could check disc run out with a dial gauge, or even just tape a pencil to the fork leg and turn the wheel slowly to check any variation in the gap between disc and pencil.

[oldgreyandslow]

Don't crack the union and tie back the lever or you will loose pressure and fluid.
Crack the union and pump lever a few times to bleed in the normal way, watching for air bubbles in the fluid as it squeezes out. Tighten bolt back up
Bleeding in this way is similar to priming as you expell the air from the top of the hose.

Now tie back the lever, assuming you have some brake [half a lever travel] so that the system is under pressure

Often the pads rub a little with brakes off if they have been worked on/disturbed, but improve when bedded in.

You could check disc run out with a dial gauge, or even just tape a pencil to the fork leg and turn the wheel slowly to check any variation in the gap between disc and pencil.

So crack union at the M/C and pump it a few times, then tighten the bolt?

Should I then bleed the system normally and then tie it back overnight or just tie it back without bleeding the calipers themselves?

As the wheels have just been painted I wonder if rub may be caused by some paint on the wheel where theb disc sits.

[arsey30]

If you bled with syringe and have some brake, so that lever comes back say half way to the bars, then bleed from the banjo as you would bleed from caliper nipple.
i.e Tie a rag around the hose to catch escaping fluid and then crack the banjo bolt, pull lever slowly to the bar and nip up the bolt, release lever and crack the bolt again.
Pull lever to bar nip up bolt.
Do this a few times until you can see no air in the escaping fluid.

Tie lever back over night once you have good lever that takes some effort to pull back to the bars, air will make its way up to the top under pressure.

There should be no paint on the disc flat mating surface and best to have none on the hub where disc pushes on.
i.e where the inner circumference of the disc mates with the bearing housing shoulder.
That way the disc will be a good fit, and no danger of binding on the shoulder and not sitting down square.

Easy to check for any run out as described.

[scooble]

or use one of these

[Chrissy_J]

From memory I did it the other way.

Filled the syringe with fluid and pumped it in through the bleed screw (via a piece of tube obviously) - that seems to expel the air upwards a lot easier.

I've tried using a syringe in both ways - pushing fluid in, and drawing fluid out - and I have to say the first method was far messier. Fluid seems to leak out from the bleed nipple thread because it's under pressure from the syringe.

Something I've noticed, though, (and i'm sure someone will correct me if i'm wrong) is that the brake lever doesn't have to be operated to allow brake fluid to flow down the line - in fact holding the lever back seems to stop fluid from entering the master cylinder via the brake line, and that tying the lever back overnight shouldn't allow air to escape the brake line, only from the master cylinder piston bore.
So in theory, if the bleed nipple is loosened and the master cylinder cap removed, any brake fluid should just run through the piston bore, the brake line, into the brake caliper and end up bubbling throught the bleed nipple (which is the highest point of the brake caliper) of its own accord.

Or am I talking rubbish?

[Neosophist]

Yep thats right, you can suck it through without moving the lever.

I've not had any problems bleeding mine up with a syringe and some tubing.

Make sure the pistons are fully in to stop any air building up behind and suck fluid through until there is no air-bubbles in, remembering to never let the fluid in the resevoir cup get low else you'll have to start all over again.

If you need to disconnect the syringe to draw through more fluid them remember to tighten the bleed nipple before you remove the syringe as air will be drawn back in otherwise.

With regards to cracking the m/c banjo.. I usually put a ring spanner around it to catch fluid, have somebody holding the lever down and crack ever so slightly until the other person feels the lever move (fluid is coming out) and tighten back up before the lever is fully depressed to stop air.

Only needs doing a couple of times if you have pain in the arse air stuck.