Soft Brake Pedal Feel, Can Not Get Rid Of It

[de Noir 0]

Hi everyone

Trouble with brakes, need help, out of ideas.

 

I'm running:

- front calipers Lucas 54mm piston (306S16 MY94)

- rear calipers Bendix stock GTI

- 23,6mm aluminium mbc, brand new (406)

- ATE powerdisc 266m front, ATE solid 247mm rear, brand new

- Peugeot stock pads all around, front brand new, rear 7tkms

- brand new standard piping all around

- sunroof

 

Now the problem:

Everything seems to work fine and car stops alright, but I can not get rid of bad pedal feel.

It needs to be pressed hard to creaate stopping force, which is what I expected with big mbc, but it'soft!

 

Changed ATE pads for Peugeot, bled the system and resealed vacuum piping from inlet manifold to brake servo, it's better but it is still not good.

 

Pedal feel and brake modulating is excellent when driving hard and fast, with high revs.

With revs down, it's getting kind of worse.

I can not get proper 'bite' at all, when short-pkicking the pedal. Kind of stuff you need in city traffic.

To get something like 'bite', I need to lift my entire foot from the floor and kick the brake pedal hard, racing style.

I guess it's okay with 23,6mm mbc. But pedal itself, it's still soft.

 

Engine off, can not get stone hard response from pedal.

Instead it remains soft, and I get hissing sound from somewhere down under all the time.

 

The only thing I haven't checked brake pedal servo drum pin to mbc stud clearence.

And haven't yet tried to disconnect the sunroof from the system.

 

 

Is this normal or best you can get with big mbc, or I got something wrong?

Wrong choice of mbc/front calipers? Thought of that too.. That should apply to pressing force of the pedal, not the general soft pedal feel, am I right?

 

Where to look next?

 

 

Thanks!

Edited August 17, 2011 by de Noir

[dee205 3]

Have you tried pressure bleeding? It took me ages to get the last bit of air out of my system when I did mine even thought I had went through the 2 man pedal pumping business a dozen times before I bought an Eezibleed kit. Well worth the money.

[de Noir 0]

Have you tried pressure bleeding? It took me ages to get the last bit of air out of my system when I

did mine even thought I had went through the 2 man pedal pumping business a dozen times before I bought an Eezibleed kit. Well worth the money.

 

 

Yes dude, I did.. mate made a brake oil reservoir cap that connects to pressurized air source, very neat solution.

I'm suspecting of vacuum servo system not functioning properly

 

Still, this is my first big mbc installatio..

23,6 with 57mm piston GTI-6 callipers works fine and feels a bit overservoed, first hand experience on 54mm calipers will be higly appriciated!

[HERMAN 33]

Is the car runing a gti6 engine? If so I belive that the vac pump gives to much vacum and over servos the car. Just a thought.

Neil

[de Noir 0]

Is the car runing a gti6 engine? If so I belive that the vac pump gives to much vacum and over servos the car. Just a thought.

Neil

 

 

no, it's a Mi - no vac pump..

[Strictly_Derv 34]

have you bled where all the pipes connect to the MC. Just do it as you would bleed a nipple but without a nipple.

[allye 530 3 Cars]

I had awful spongy pedal when I was bleeding my system, new lines, ms, rear cyclinders basically all new. Turned out to be the compensator was buggered! Worth a try.

[de Noir 0]

compensators are new too..

 

system is bled with air pressure applied to brake oil tank, AND pumping the pedal, got clean fluid flow at both rear wheels..

 

checked 23.6mm mbc stud vs 19.8mm stud, today they're the same

 

 

I guess bleeding on more time won't hurt