brake help

[paul7278]

Right I changed my standard dturbo front brakes at the weekend for hdi 266 mm set up. This consisted of second hand callipers new discs and pads. However I can't bleed them up. I've pressure bleed them 4 times and get a OK pedal but not hard and with engine on the pedal creeps to the floor. Any ideas?

[swampy]

Sounds like you have air in the abs pump

[Jimbo]

Id say need a proper bleed, try all four start farthest from master cylinder

[paul7278]

Non abs. Just clamped hoses and still the same. I'll re bleed furthest first.

[Alex]

May sound daft, but have you bled the rears as well? You may have a problem with the master cylinder.

Always check the basics first.

[paul7278]

Bled front and rear in sequence for the 6th time both with a pressure bleeder and manual. I clamped the hoses and stays the same. Seems so odd as my standard d turbo brakes were fine.

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Would I benefit from putting a bigger master cylinder on to run the 266mm?

[Mattcheese31]

Bled front and rear in sequence for the 6th time both with a pressure bleeder and manual. I clamped the hoses and stays the same. Seems so odd as my standard d turbo brakes were fine.

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Would I benefit from putting a bigger master cylinder on to run the 266mm?

You don't need a bigger mc no, so you've bled back left, front right, back right then front left yeah?

[Jonny b]

Leaky seals on the new calipers??

[paul7278]

no visible leaks off claipers.

[powerandtorque]

If the pedal creeps to the floor under sustained pressure and there's no leaks, replace the MC as a matter of course.

Basically, if the pedal is creeping then either fluid is leaking out of the system or its leaking back past the seals in the MC under pressure. If it was just air in the system, the pedal would be spongy and/or would have a fair bit of dead travel, but shouldn't creep.

Bleeding brakes on old MC's can damage the seals internally and cause issues like you're seeing.

[Jonny b]

^^^^^ exactly that!

[Jimbo]

Ive got a gti6 23mm masyer.cylinder for sale 20 quid posted

[paul7278]

right got a brand new master cyclinder for £35 so il give it a go tonight and let you guys know.

[paul7278]

Just changed the master cylinder for a brand new one. So the car now has new 266mm discs new pads second hand callipers new rear cylinders shoes etc. Any guess what still the same and creeping. Its doing my head in now wish I kept standard dturbo set up.

[paul7278]

Could it be flexible hoses

[tigerstyle]

Could it be flexible hoses

Only if they are leaking.

[Jonny b]

They could be expanding under pressure though!

[powerandtorque]

Are you absolutely sure that there's no slight leak anywhere? Perhaps the rear slave cylinders if it's a drum beam?

The pedal can't creep to the floor under constant pressure unless the fluid is going somewhere!

Obviously if there's loads of air in the system or the pads aren't sitting square to the disks then the pedal will be spongy and could feasably go to the floor if you were to press the pedal hard enough, but that's quite different to pedal creep. Pedal creep is where you hold the pedal under sustained constant pressure and it slowly sinks to the floor.

[Jimbo]

Have you got snapped bleed nipples on the front? Or bleeding them off.hose?

[mr_fish]

I would of said rear wheel cylinders, whip the drum off to check

[paul7278]

All sorted. Rebleed them with a eazi bleed and now fine.