Technical Weird brake problem

[mattjohndavies]

Hi all,

Only just signed up to the forum but long time reader. I have a Punto Mk2 1.2 8v 5dr, 2001.

Tonight I noticed a slightly strange issue with my brakes when I parked on a slope. I had pressed the footbrake just enough to stop the car, and when I applied the handbrake, the pedal suddenly pressed down further without more pressure being applied to the footbrake. It was like only the rear drum brakes were being engaged by the footbrake and when I pulled the handbrake on and took the pressure from the pedal, the pedal slipped down until the front brakes engaged.

I haven't had a chance to check anything out yet, but I can't see it being an issue with either the master or slave cylinders as, correct me if I'm wrong, any issue with these affect the front brakes as well as each slave cylinder controls an opposite front and rear brake. My ideas would be bleeding the brakes to check no air is present in the front brakes, or maybe the brake proportioning valves, although I wouldn't imagine both would go (there's one on each slave cylinder correct?).

Any ideas would be highly appreciated as I am slightly concerned that if this got worse and the brakes were applied heavily to the rear with none at the front it could cause locking of the rear wheels and an ensuing accident.

Many Thanks

Matt

 

[Brendan W]

You may have a problem with a sticky rear slave cylinder or shoes ( there is a slave on each wheel , diagonally linked). The foot pressure is not engaging the rear brakes fully until the handbrake effort overcomes whatever is sticking.

 

[fingers99]

To my mind, sounds like master cylinder failure.

One of my Cinqs would do this: come to a stop going downhill, car stops fine, then starts to roll forward until you re-apply the brakes..........

By all means check the rears, but in my case a new master cylinder did the job. Black brake fluid tends to confirm (finely ground up seal).

 

[Ziggy122]

Its a case of strip and clean and check the piston is free to move
just for the love of god - PLEASE dont press the foot brake without the shoes fully attached

it could forwell be a sticking set of shoes = Handbrake allows it to bite better
You could have a leaky or sticking slave cylinder

I dont think M.cylinder personally - but i could be wrong

olde punto used todo just that, and it was good to brake hard
If you put the handbrake on - THEN press the brake pedal - does it feel more solid all of a sudden?

Ziggy

 

[mattjohndavies]

Thanks for the advice guys. I've got the MOT on Monday so will see what comes up on that if anything.

Ziggy - I'll try that tomorrow and post back with what I find.

If nothing shows on the MOT then I'll have a look at the master cylinder, slave cylinders and drums/shoes to try and find the issue.

Matt

 

[Brendan W]

If it is something at the back, it's unlikely that both sides are affected equally so ......... If someone was to open up the access cover to the handbrake adjuster and looked at what happens to the cable equaliser as the handbrake is applied you might be able to pin it down - rubber neck required. Bear in mind the cables are elastic so some movement is to be expected , just not a big kick to one side.