Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

VL Brakes Issue!

markER717

Un-Donated Member
Joined
Jun 7, 2009
Messages
472
Reaction score
1
Points
0
Location
Geelong, Victoria
Members Ride
1990 3.8L VN Calais S1
Okay so another problem with my car.. lol. But when I put my foot on the brake pedal with the car off it feels normal, like it should. But when the car is running, the pedal sinks all the way to the floor! It still stops the car (not sure how well as I've only tested it going slowly) but it doesn't start working until a couple of cm off the floor.. the system has been bled twice and it has disk brakes all around. I am truly stumped. I was thinking possibly diaphragm leak in the booster? but that's all I got.. Any Ideas guys?
 

Jxfwsf

Well-Known Member
Joined
Feb 20, 2011
Messages
4,852
Reaction score
108
Points
48
Location
Aus
Members Ride
commodore
with the engine off and pumping the pedal a few times it should go hard and not press in very far, should not feel "normal" like it does when an engine is running.
sounds like you need to bleed the system.
 

Jxfwsf

Well-Known Member
Joined
Feb 20, 2011
Messages
4,852
Reaction score
108
Points
48
Location
Aus
Members Ride
commodore
if it was a vac leak and the booster wasn't getting assistance the brakes would be hard all the time and you'd almost have to use both feet to stop.
 

Cheap6

New Member
Joined
Jun 19, 2005
Messages
2,498
Reaction score
74
Points
0
Members Ride
VP Exec
If it has been bled properly (if there's air in the systems it should pump up and hold pressure) and there are no external signs of fluid leakage, maybe the brake M/C is leaking internally?
 

drewVHSS

Donating Member
Joined
Apr 1, 2010
Messages
713
Reaction score
6
Points
18
Location
Gosford Central Coast
Website
stores.ebay.com.au
Members Ride
'83 VH SS, '79 Green VB SL '92 S2 VQ Caprice
disc or drum rear?
If drum, the slave cylinders can leak and it takes a while for the stain to become visible.
M/C's have been known to leak into the booster, leaks wont be detected for a while untill the fluid finds it's way out via a seam or eats the diaphram.
How old and worn are your rotor's and pads?

I have laying around a VL commodore (jap type) booster and 15/16's master (disc rear) alternatively you can bolt up a 1" master from VL VN VP (which i also have some laying around) p.m. me if u need bits
 

markER717

Un-Donated Member
Joined
Jun 7, 2009
Messages
472
Reaction score
1
Points
0
Location
Geelong, Victoria
Members Ride
1990 3.8L VN Calais S1
with the engine off and pumping the pedal a few times it should go hard and not press in very far, should not feel "normal" like it does when an engine is running.
sounds like you need to bleed the system.
Thats what I meant by normal mate, thats exactly what it does with engine off. But when the car is running, the pedal goes all the way to the floor and only just engages the brakes at about 2-5cm off the floor. It only shows signs of not being right when the engine is running.

If it has been bled properly (if there's air in the systems it should pump up and hold pressure) and there are no external signs of fluid leakage, maybe the brake M/C is leaking internally?
I think Maybe I need to bleed it again, but im not sure why this is only an issue when the car is running.

disc or drum rear?
If drum, the slave cylinders can leak and it takes a while for the stain to become visible.
M/C's have been known to leak into the booster, leaks wont be detected for a while untill the fluid finds it's way out via a seam or eats the diaphram.
How old and worn are your rotor's and pads?

I have laying around a VL commodore (jap type) booster and 15/16's master (disc rear) alternatively you can bolt up a 1" master from VL VN VP (which i also have some laying around) p.m. me if u need bits
It is disc rear end, and rotors and pads have been replaced recently. I may be interested in the 1" master though?
 
Top