Brake problems

Hi guys, I have a Disco 1 v8 92,

I had spongy brakes so I bleed the system and not a lot changed. Ive look on different forums and they say reservoir leaking or full with crap,


So I’ve ordered and master cylinder and reservoir kit witch I’ve changed and cleaned out, then I also changed the pads and re-bleed the system, all crap came out of pipes and flowing well,


The peddle seemed to harden up and feel fine until I started up the engine and it went back to being spongy any advice or help would be great full


Cheers

Aiden

It will go a bit spongy when engine is running, it’s the servo doing its job, it’s best to bleed the front callipers by using a bleed pipe with three connections, basically bleed all nipples on the calliper at once, that way you are more certain to get all the air are out,
I also replaced all my flexible pipes with Goodrich stainless braided pipe they also make the pedal firmer,

Europa486 said:

It will go a bit spongy when engine is running, it’s the servo doing its job, it’s best to bleed the front callipers by using a bleed pipe with three connections, basically bleed all nipples on the calliper at once, that way you are more certain to get all the air are out,
I also replaced all my flexible pipes with Goodrich stainless braided pipe they also make the pedal firmer,

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Thank you I’ll have a go with that. But also the pedal goes all the way to the floor with not a lot of braking

Cheers

Could well be the master cylinder, I know it’s new but could still be faulty, when you pump the pedal when bleeding
Are you getting a good amount of fluid with each pump? If not then it’s likely the Master cylinder is faulty,
I would only use genuine or OE for brake parts,
I take it you have no leaks anywhere? I replaced my pistons and seals on the callipers when I overhauled the system,

Europa486 said:

Could well be the master cylinder, I know it’s new but could still be faulty, when you pump the pedal when bleeding
Are you getting a good amount of fluid with each pump? If not then it’s likely the Master cylinder is faulty,
I would only use genuine or OE for brake parts,
I take it you have no leaks anywhere? I replaced my pistons and seals on the callipers when I overhauled the system,

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yes it comes through fine, and no I can’t see any leaks though out the whole system

Then another good bleed with new fluid ( don’t use the old) start with rear n/ s then rear O/s
Followed by n/s front then lastly o/s front, use the three pipes for the front and it should be good,
New pads until bedded in will also make the pedal softer,
The reason you don’t reused fluid even if it’s new is it will contain Minuit air bubbles, so would need to be left standing for a day or so,

Does pedal harden up after a couple of pedal preses, or stay long and soft all the time?

lynall said:

Does pedal harden up after a couple of pedal preses, or stay long and soft all the time?

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when I pump it goes little bit harder, then it will just drops to the floor

Does soudn mcyl related, but Iirc the early D1 had a concentric mcyl pushrod set up, ie it might ot be set up correclty?
Do not ask me how to set it up, I have no idea! assume just a knatts cock free play?

aidenV8disco1 said:

when I pump it goes little bit harder, then it will just drops to the floor

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Your opening post u said “went back to being spongy” so whats changed?
A seal in the master cylinder can easily fail after pressing the peddle down to the floor when bleeding, due to corrosion on the piston. Was the new master cylinder band new?

lynall said:

Does soudn mcyl related, but Iirc the early D1 had a concentric mcyl pushrod set up, ie it might ot be set up correclty?
Do not ask me how to set it up, I have no idea! assume just a knatts cock free play?

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No the brake master just bolts straight to the servo unit so doesn’t need adjustment,
The clutch master has the concentric adjustment, very easy to adjust, just rotate the through bolt
Until it’s in line with the brake pedal,