soft/low brake pedal

[sxi ss]

hi my vr ss has vt front brakes , vt master cylinder and booster fitted, zinnoli dds rotors and hard pads fitted , i just cant get the pedal right on it, tryed 2 boosters/3 master cyklinders and 2 sets of calipers help please

 

[hako]

Have you bled the system of air completely?...a pressure bleed is best as it really forces the fluid thru the lines.
Did you use the pushrod from pedal to booster from the VT...not sure if this matters.
I've usually found that it takes a week or so for the pads to bed in to the shape of the disc, and during this period the pedal will be soft and low. Hard pads will take longer.

 

[oscar03]

check for air. a problem like that is sometimes an indication that there is air in the rear lines. it causes the pedal to travel further before having much effect and then is very spongy. air in front lines tends to brake for a moment then fall away really quickly and also has a spongy peddal. also air can be hard to find sometimes just because you cracked the bleed nipplle a few times and didnt see any bubbles doesn't mean its free of air. i have used a large syringe and clear rubber hose to suck throuh the brake fluid before this works pretty well you just need to be carefull not to let the master cylinder go dry or you are back to square 1. thats just from the experiance i have had in the past not any specific source. but i hope it helps

 

[sxi ss]

the car has had this issue ever since i have had it about 2 years , pads and rotors done 6 months ago, master cylinder, booster and fluid swaped again yesterday, no better than standard vr booster master cylinder setup, swaped front claipers and rebleed today , still the same,,, clamp front brake hoses and pedal is great so im picking it has to be in the front end somewhere, what are the shims people talk about on here when putting vt brakes onto vr's i dont know what hubs mine has as i didnt do the origional conversion , i just got stuck with the headache

 

[BlackVXGTS]

Did you bench bleed the master cylinder before you installed it?

 

[sxi ss]

i have no idea a local garage done it for me , im asumeing they know what they are doing

 

[hako]

Try a brake place - get them to pressure bleed the system.

Edit....found this on another thread - may be relevant - if bleed nipple is not at top you may not be able to bleed all the air out: "might pay to add that you gotta make sure the bleed nipple is at the top when fitting new calipers."

 

[RX25SE]

Has the booster pushrod been adjusted correctly?
If not, it may be preventing the compensating port in the m/cyl from being open when the brakes are released.

Are you getting plenty of fluid when you bleed it?

 

[pete30nz]

Hi people,
My vr v6 abs brake pedal was right to the ground before it would start to work last week, the car had been sitting around for over a year.

We put another brake master on, fresh fluid through system, and bled it half a doesen times, but the pedal still went to the ground with out trying hard to push it.

Turned out the slides on the rear calipers were seized.

Replaced front and rear piston seals, re bled system with engine running, and with engine turned off.
I have a better pedal there now, but would be great if It could be better like a non abs pedal?

Hope this can help some one with any brake issues.

Pete

 

[pete30nz]

Update: my Vr was taken for w.o.f recheck, and the brake pedal still failed. The w.o.f man said the pedal should be firm like his late model commodore.
We swapped over calipers last night and bled the system as good as we could, but pedal still has at least an inch or more travel.

The front passenger wheel is really hard to turn with brake caliper on, i used a 2 foot bar between wheel studs to turn hub, with lots of strength, and it moved very slow.??

I haven't tried clamping any brake lines at this stage, I need some clamps that I don't have.

Must still be air in the lines I'm guessing, because the pedal has at least an inch and more travel in it...?

Any ideas will be appreciated please

Pete