Brakes not working right

[Trip]

My brakes are not holding as they should. They are not locking wheels even when i slam on the brake pedal at very low speed.

I have already flushed the system and put in fresh fluid. Checked and re-checked for air in the system. When i pump the pedal with engine off it does get firm. Keeping pressure on the pedal and I switch on engine, the pedal sinks in around 20mm.

Could it be the master got bust ?

 

[npulsar]

have you got abs

 

[Trip]

No. I have removed the ABS and bypassed the actuator.

 

[GTIR-LOZ]

is it all the time i.e does it only do it after bends etc as play in the wheel bearings can cause this pedal drops further on first push second its fine

 

[Trip]

Unfortunately its all the time

 

[Trip]

Also note that the pedal feels very normal.. its not too soft and hardens and stops 3/4 down with engine ON.

Even at very low speeds (1st gear 2.5krpm) te car does not stop abruptly when i slam the pedal.

My setup:
Bypassed ABS actuator like so : http://i131.photobucket.com/albums/p298/Trip_gtir/absMod.jpg
Inlet manifold changed with vacuum feed like so : http://i131.photobucket.com/albums/p298/Trip_gtir/Image029.jpg
Fluid: Delphi Lockheed ULTRA DOT 5.1
Calipers and Pads : standard
Hoses: Goodridge

 

[stumo]

It sounds like the master cyl.

Were the brakes working ok before? have you just changed something....like calipers etc

With the engine off and you have pumped the vacuum out of the servo....
1.Does the pedal drop when you keep pressing it?

2.Does the pedal drop when you press lightly on the pedal?

 

[Trip]

It sounds like the master cyl.

Were the brakes working ok before? have you just changed something....like calipers etc

With the engine off and you have pumped the vacuum out of the servo....
1.Does the pedal drop when you keep pressing it?

2.Does the pedal drop when you press lightly on the pedal?

Brakes were fine before removing engine and modifying the vacuum and ABS. Calipers and pads are the same. The car was off the road for almost 3 yrs without engine so brakes were not used during this time.

I will verify 1 and 2 this eve and report back.

In the event of being the master, is it an engine out job ?

 

[stumo]

I wouldn't think you'd have to remove the engine to do the master cyl, maybe have to remove the inlet manifold ...

 

[GTIR-LOZ]

you could also have a seized piston in the caliper, due to not using them for so long

you can change the master cylinder in situ

 

[Trip]

It sounds like the master cyl.

Were the brakes working ok before? have you just changed something....like calipers etc

With the engine off and you have pumped the vacuum out of the servo....
1.Does the pedal drop when you keep pressing it?

2.Does the pedal drop when you press lightly on the pedal?

I pumped the pedal until it got firm and i pressed hard on it for about a minute and it did not move.

Did the same but this time gently and it didn't move either.

Is it a good or bad sign ?

 

[Trip]

you could also have a seized piston in the caliper, due to not using them for so long

you can change the master cylinder in situ

I thought of that too, but would it effect all 4 corners ?

 

[stumo]

I pumped the pedal until it got firm and i pressed hard on it for about a minute and it did not move.

Did the same but this time gently and it didn't move either.

Is it a good or bad sign ?

that's a good sign, usually the pedal will drop if the seals are poor.

 

[Trip]

Thanks for your input guys.

I will try re-bleeding the system with engine running maybe it will do a difference.

How can i test if my calipers have seized pistons ?

 

[stumo]

remove the pads and see if you can push the pistons back....watch out that they don't pop out!

 

[whytie]

I remember when I first done the rears on mine it took me about an hour to realise the pistons screwed back in, I was squeezing that bastard for ages

 

[jambo_gtir]

I remember when I first done the rears on mine it took me about an hour to realise the pistons screwed back in, I was squeezing that bastard for ages

:lol: i spent ages trying to push the front ones back with a G-Clamp. The cylinder wasn't budging so i thought id go press the brakes slightly to move them back out a bit...... forgot to take clamp off and ended up with the g-clamp snapping in half and flying across the road 8)

 

[dencon]

I might be wrong, but I thought you had to change the proportioning valve when you remove the abs. I know they are different on the abs cars and the non abs ones. cheers den.

 

[Trip]

remove the pads and see if you can push the pistons back....watch out that they don't pop out!

I removed the rear calipers today and the piston on both calipers are moving out. Mind you i had to use a G-clamp to put them back in. I pumped them in and out a several times and they don't seem seized.

The problem lies here, With the brake pedal pressed, I managed to turn the wheel of one side using a breaker bar stuck between the studs. The other wheel was jammed though. Thats how bad my brakes are.

I will find some time to inspect my front ones.

 

[Trip]

I might be wrong, but I thought you had to change the proportioning valve when you remove the abs. I know they are different on the abs cars and the non abs ones. cheers den.

Can anyone verify this ?