Brakes not working

[vodkakid]

Hi,

I've just had some engine work done on my mini which resulted the car sitting sill for about 8 weeks. When the car came back to me the brakes were very soft. Since then they have been bleed about 15 times and the servo has been replaced with no effect. They were fine before the rebuild.
The brakes are mini sport 4 pot with braided hoses which have been checked as have the drums. Any ideas what might be up??

[guru_1071]

had the people working on the car removed the brakes as part of the job they where doing, or have they failed just from been stood?

what year car is it?

[vodkakid]

As far as i know they were left on but i'm not sure (it was engine out work) the mini is from1973

[guru_1071]

where are the bleed nipples on the calipers?

[vodkakid]

Yes, Mini sport alloy 4 pots.

[guru_1071]

vodkakid said:

Yes, Mini sport alloy 4 pots.

sorry, i meant where abouts on the calipers are the bleed nipples?

at the top (where they should be)

or at the bottom (where loads of peole put them if they have taken them off - this way the brakes wont bleed up)

[vodkakid]

I'll find out thanks

[vodkakid]

They are at the top.

[vodkakid]

Any ideas? please.

[Ranger 6]

Master cylinder seals OK? That was the problem with mine when the brakes failed.

[Cooperman]

Hi Andy,
The problem, as 'Ranger' says, could be the master cylinder. When the brakes are bled the pistons have to travel over a part of the cylinder which is not normally used and a small 'step' can have developed which ruins one of the seals. I've had that happen a few times. It's extremely prevalent in the tandem vertical cylinders, although it happens in other types of master cylinder as well.
Did you get it rolling-roaded yet? If you did, what is the power?

[vodkakid]

Hi Peter,
Thanks for the reply, I haven't even driven the car yet because of the brake problem being so bad.

[mk2 24v]

it may possible be the rear brakes causing the iffy pedal. friends mini had KAD 4pots fitted, only to have a spongey pedal

upon trying to bleed out the brake system, there was no fluid coming through a rear wheel cylinder at all

may be worth a check of all the brakes for operation

[Cooperman]

Andy,
I saw Chris bleed out the brakes and there was no air coming out.
I do reckon it it the master cylinder as there is not much else it can be, unless a rear wheel cylinder has failed. It is funny how brakes can become spongy after rebleeding even when nothing has actually been done to the brakes themselves. I have had several master cylinders fail after being fully stroked following disconnection for other work over the years. The worst culprits being the tandem twin ones fitted to late non servo cars. Also had it on a single system Cooper S as well.
It could be the 4 pots, I guess, although I cant see why that should be.

[vodkakid]

Cooperman said:

Andy,
I saw Chris bleed out the brakes and there was no air coming out.
I do reckon it it the master cylinder as there is not much else it can be, unless a rear wheel cylinder has failed. It is funny how brakes can become spongy after rebleeding even when nothing has actually been done to the brakes themselves. I have had several master cylinders fail after being fully stroked following disconnection for other work over the years. The worst culprits being the tandem twin ones fitted to late non servo cars. Also had it on a single system Cooper S as well.
It could be the 4 pots, I guess, although I cant see why that should be.

Hi Peter,

Would the change in carbs affect them (vacuum pipe?)

[vodkakid]

Car now leaking from alot of holes

[Cooperman]

vodkakid said:

Cooperman said:

Andy,
I saw Chris bleed out the brakes and there was no air coming out.
I do reckon it it the master cylinder as there is not much else it can be, unless a rear wheel cylinder has failed. It is funny how brakes can become spongy after rebleeding even when nothing has actually been done to the brakes themselves. I have had several master cylinders fail after being fully stroked following disconnection for other work over the years. The worst culprits being the tandem twin ones fitted to late non servo cars. Also had it on a single system Cooper S as well.
It could be the 4 pots, I guess, although I cant see why that should be.

Hi Peter,

Would the change in carbs affect them (vacuum pipe?)

I can't think why it would. The manifold vacuum will be virtually the same and if the servo pipe was leaking the engine would not run properly as it would be running much too lean.
I still suspect that the old master cylinder seals have degraded when pushed right down the cylinder bore. It's a not uncommon problem.

[Cooperman]

vodkakid said:

Cooperman said:

Andy,
I saw Chris bleed out the brakes and there was no air coming out.
I do reckon it it the master cylinder as there is not much else it can be, unless a rear wheel cylinder has failed. It is funny how brakes can become spongy after rebleeding even when nothing has actually been done to the brakes themselves. I have had several master cylinders fail after being fully stroked following disconnection for other work over the years. The worst culprits being the tandem twin ones fitted to late non servo cars. Also had it on a single system Cooper S as well.
It could be the 4 pots, I guess, although I cant see why that should be.

Hi Peter,

Would the change in carbs affect them (vacuum pipe?)

I can't think why it would. The manifold vacuum will be virtually the same and if the servo pipe was leaking the engine would not run properly as it would be running much too lean.
I still suspect that the old master cylinder seals have degraded when pushed right down the cylinder bore. It's a not uncommon problem.

[vodkakid]

Cooperman said:

vodkakid said:

Cooperman said:

Andy,
I saw Chris bleed out the brakes and there was no air coming out.
I do reckon it it the master cylinder as there is not much else it can be, unless a rear wheel cylinder has failed. It is funny how brakes can become spongy after rebleeding even when nothing has actually been done to the brakes themselves. I have had several master cylinders fail after being fully stroked following disconnection for other work over the years. The worst culprits being the tandem twin ones fitted to late non servo cars. Also had it on a single system Cooper S as well.
It could be the 4 pots, I guess, although I cant see why that should be.

Hi Peter,

Would the change in carbs affect them (vacuum pipe?)

I can't think why it would. The manifold vacuum will be virtually the same and if the servo pipe was leaking the engine would not run properly as it would be running much too lean.
I still suspect that the old master cylinder seals have degraded when pushed right down the cylinder bore. It's a not uncommon problem.

Hi Peter,

It has a brand new master cylinder and still has soggy brakes

[oldboyracer64]

a shot in the dark but on my sons mini the brakes all worked but the pedal felt very long and spongey, it turned out to be the connecting rod that goes into the servo was wound out too far (so the brake pedal and clutch pedal sat about the same height) as soon as we wound the connecting rod in to raise the pedal it helped and made it easier to bleed the brakes and after that we had no more problems, hoped this helps, David.