Mpi brakes .

[swifty]

Hi . I've got 99 plate mpi john Cooper s works . Both the front brake calipers are sticking on . It's definataly not the calipers or pads . Now if I undo the bleed nipple on each caliper for a second it releases the brakes . So I'm thinking it's either the master cylinder or that brake compensator thingy on the bulkhead , under the servo . Has anyone else had this problem ? Trying to decide witch one to change ..... Ken

[Vegard]

Change your brake hoses. Job done!

[swifty]

Vegard . The brake hoses I put on were aeroquip ones . I think you may have a good point here though because although they looked mint they were in my stock of spares for years . The master cylinder was reconditioned by me with a mini spares seal kit , witch I have done before with no problems . Both n/s and o/s brake calipers stick on together . Is it possible I have 2 faulty hoses ? . For how long it takes to do I'm gonna change the hoses . Il let you know how it went . .... Good point though thanks .

[GraemeC]

Is all the linkage free through the servo - could it be binding/siezing and therefore holding the master cylinder activated?

[swifty]

Point noted , il have a look at that Graeme

[ianh1968]

Someone else on this forum was discussing a very similar problem,
but this was in respect of the pedal pushrod length on various old-type
set ups.

The general idea was that the hole in the cylinder where the fluid enters
the cylinder was either being blocked and not released or maybe the other
way round.

People were talking about curing it using the same method as you
describe, ie the brakes released when the bleed nipple was released...

I would say that my '93 Mini has a horizontal master cylinder with an
adjustable clevis/pushrod assembly, is the MPI one similar?

If so, has the pushrod been adjusted to an inappropriate length?

Ian

[swifty]

Hi Ian . No adjustments have been made to the pushrod or linkage assembly . It's all standard mpi.

[ianh1968]

Hi Ian . No adjustments have been made to the pushrod or linkage assembly.
It's all standard mpi.

It was just a thought...

For the amount of work involved, is it worth just slackening off the
locknut and giving it a wind? That's got to be easier than changing
the pipes and bleeding the brakes. It will either cure the problem
or make no difference!

Try it one way, then the other... As long as you note how much you've
moved it by, you should be able to put it back where it was in the first
place quite easily.

I know that "if it ain't broke, don't try to fix it", but it may have been
borderline in the first place. The pedal position will always end up
being the same as it gets returned to the top by the spring. What we
don't know is the static position of where the piston is inside the master
cylinder...

You could press the brakes until they are "locked", then push out the
clevis pin to see if that helps? If they release, you know where to look...

Ian

[swifty]

In case anyone else has this problem thought I'd let you know how I got on . Firstly I changed the discs and pads because the brake locking had made them so hot that they didn't run true . I then changed the hoses . Problem still the same . I then changed the master cylinder . Again still the same problem. So then I slackened off the adjustment of the rod through the servo . Still the same problem . I was now convinced although I had slackened off the adjustment as far as I could go , that this would be the problem . So I took off the master cylinder and ground off about 3mm off the rod that goes through the servo . Built it back up , bled the brakes again and hey presto , problem solved . As ianh said because the pedal returns to the same position it's hard to judge the position of the rod to the master cylinder . Well done that man . In retrospect I should have looked into the adjustment a bit more .

[ianh1968]

swifty,

Glad you got it sorted... My own brake setup is similar, so if I get
that problem myself in the future, I will know where to look.

I was only "passing on" information that I read elsewhere on this
forum, but I am glad to have been of assistance. My thanks go to
those on the "other" thread...

The good thing about these Mini forums is that we can all learn
different things from each other, no matter what our own experience
may be.


Ian