\'kin dangerous brakes !!!

[Big Al]

:confused:  Going off my FD big time. At the moment it\'s not a daily driver and so sits around waiting for weekends for drive around.
Thing is, three times now the brake pedal has gone hard and not really actuated the brakes without me excerting all the pressure I can muster on the pedal. One time I had to haul it up on the hand brake before it clouted another car.
If I take my foot off the pedal and re-apply they return to working normally. It\'s almost as if the servo is working only occaisionaly.
 
All help appreciated here before I bash into something precious, worse than that....wreck my lovely car.

[m1tch]

When did you bleed the brakes last?

[Jono FD3]

old brake fluid, (should be changed every 5 years they recomend), seized caliper will also drasticaly reduce brakeing, overly warn discs..... basicaly anything on the hubs could be at fault! worth starting at the cheap bits & working up:

Fluid
Check calipers are free (do a seal kit if needed)
pads
discs
etc.

Jono

[SiH]

When the pedal does nothing - is that after some \'enthusiastic\' driving? Not  much change in pedal effort but reduced braking is asymptom of overheated brakes. But if it\'s doing it with normal driving, you have another issue.

Pop the front pads out and check all pistons move freely and easily

When did you bleed the brakes last?

Knackered fluid will lead to a spongey pedal, not a wooden one.

[leon]

What about the one way vale from the engine to the survo, what would happen if that was dead?

[tinker-27]

does the pedal go rock hard as if no engine ? if so its the servo or lack of vacuum, there is a one way valve in the servo hose check there is no splits in the hose or it is not collapsing, is it the correct hose, if not i would change the servo for safety sake  they are cheap second hand,if its going to the floor then it could be fluid related,

[steve garbutt]

It will more than likely be the pipe from the servo to the plenum.
I had the exact same problem for 4 weeks, it would work perfectly then out of the blue it would be solid and like i have no brakes.
Mine looked perfect until i removed it and checked the underneath that you cant see, age had cracked it and made it split, so under certain conditions the split would open up and there would be nothing going to the servo to assist my brakes therefore making them feel like they are rock hard.

Tinker types faster than me

[Jovic82]

anyone know what size the pipe is?

[clive]

As said above,

This will be the right angled rubber elbow from the engine to the servo up on the bulkhead,

If you either have a split  the engine idle will be funny if not the pipe has collapsed internaly or the one way valve up the pipe is now blocking off the vacume that makes your brakes feel all nice and soft helping the car stop a little better than now !

[clive]

anyone know what size the pipe is?

It\'s 10mm but you need the one way valve up the pipe so I would advise the proper pipe

[Jovic82]

do you have these clive? or know anywhere to get one? if not i suppose its a call to mazda - part numbers please!

[m1tch]

I think there is a procedure in the hayne manual for testing if the servo is working, with the engine off, put your foot on the pedel, then turn the engine on and the pedel should move a bit.

But if you have to reapply the brake pedel I would check fluids still, its something people forget to check!

[steve garbutt]

I think there is a procedure in the hayne manual for testing if the servo is working, with the engine off, put your foot on the pedel, then turn the engine on and the pedel should move a bit.

But if you have to reapply the brake pedel I would check fluids still, its something people forget to check!

This is correct but you need to pump the pedal while the car is off till the pedal is hard, also the problem with this test is that mine only ever did it once a week, possibly when certain conditions were met.

Removing the pipe is only a 2 second job.

[clive]

You can use a plain 10mm rubber fuel pipe to get you out of trouble and the number for the proper part is F100-43-640A

[Big Al]

A big thanks for so much helpful advice, you guy\'s are great.
Just checked the pipe in question and on the outside it appears in good condition so I guess either it\'s collapsed internally or the one way valve is playing up. I\'ll definately get a new one.