Brake Problems Again!

[Jamie.]

After having the 4pots fitted i thought this would be the end of all my problems.

Anyway, took the car out for a quick spin and stamped on the brake pedal hard at about 40ish and the pedal went straight to the floor with a grinding noise. Tryed it again and the same thing happend? When braking non-hard it doesnt do this (go to the floor) but the pedal is a bit spongy.

Just crawled home a bit annoyed. Any suggestions?

[Jamie.]

Ohh and when pumping the pedal from stand still it feels spongy but doesnt hit the floor either?

The only thing i can think of is there is air getting into the system? And the grinding noise is the pads against the disk but louder as its not stopping the car?

[MatBrown]

The lack of pedal would lead me to say the servo or master cylinder was at fault.
As for the grinding make sure you check all the brake pads as i have heard of the friction material being ripped clean off.



Mat.

[david932]

swap ur calipers with me

mine work fine

[McPikie]

Master cylynder is leaking from somewhere.

Cover it in talc and get someone to stamp on the pedal, see where it comes from

[Jamie.]

ok i took it for another drive today and if i progressivly brake harder it works fine and brakes normal and hard. if i stamp on at speed the pedal will just go to the floor and make that odd grinding noise. it still appears to be dropping speed when making that noise its just diff to tell as the car slows so quickly. i somewhat feel that it is deff either the master cylinder or abs as the feed back through the pedal seems quite exagerated.

[VIPERONE]

thats dangerous imo.

brakes are v important....master cylinders are cheap £30ish, relatively easy job as well.

the servo itself is a little harder.

[richy]

ah i forgot about the abs, have u ever heard yours before lol? mine makes a really stupid noise, although never had any problems with the pedal dropping

[eternalife]

Well Im no expert but i would suggest the following:

1. What pads are u using? some pads require a lot of heat in them before they work efficiently. I am guessing that the pads are bedded in??

2. The 4 pot calipers you have - are you sure they have the correct piston diameter? as 4 pots are available in a number of different piston sizes - if the piston size is larger then your master cylinder is capable of working with - it will not be able to apply enough pressure to the piston and therefore u get an initial spongy feel on your brakes.

3. when the brake conversion was done did you replace to custom made hoses - I am sure standard hoses are not long enough in length and therefore there is a risk that the hoses could detach themselves or leak.

4. Lack of stopping when u slam the brakes suggests air in the system as you have mentioned. Gas/air far more compressible than liquids therefore a 'slam on the brakes' will cause the air to compress rather than the brake fluid - if u do it gradually the forces exerted on air/brake fluid can be evened out to some extent.

5. the grinding noise you have suggested seems as though the contact between pads and discs is not as all should be. Try ensuring the installation of you braking system is tight and doesnt move (i.e disc / caliper / pad - both lateral and radial movement). Also - i have heard of some brake pads making weird noises - what pads are you using?

6. Finally - someone else has suggested a leak - which can be attributed to all of the above problems you are having.


Good luck!!

[Daz.]

Have you tried disconnecting the abs out of curiousity?