Regarding spongy brakes (90)

[cuisinartvette]

If I had a slight vacuum leak, would that cause this? Still have yet to rebleed them and noticed if I drive the car HARD as far as braking goes they grab much better, but they still suck. All new pads/rotrs btw. Noticed the vacuum pump comes on for a split second every few seconds . Plenum pull? Car runs great.

[phrogs]

um it shouldnt the vacum is just for the brake booster it shouldnt have anything to do with your brakes.

The vacum pump is keeping up the pressure to the vacum canister under the plenum has nothing to do with the brakes, You only get vacum on the booster while the car is running

[tomtom72]

I've been looking at brake threads in the C4 gen & tech sections lately to get some learn'in before I have to do my brakes.

It seems that the anti-lock device is the root of all evil as far as trapping air goes. The people that have used pressure bleeders seem to have less trouble gettin' the air out. Then there are the people that say to do the job correctly you need to activate the anti-lock unit with a tech1A. Then there are the people that say that if you use a p-bleeded you have to bleed the anti-lock pump and then bleed the system....then either let it sit (how long?) and do the whole bleed over again, even the pump.

I don't know what to think about this. I have a small bit of air in my system...gotta hit them once to get a high pedal...they work but the air in my system I've been chasing for a while...I don't have a p-bleeder and I'm about ready to go that route to see if that helps. I've bleed them the old way and it don't get it.

Sorry i don't have an answer. Just thought I'd pass on what I found elsewhere.

Tom

[ShawnZR-1]

The last time I bled my brakes, I "activated" the ABS by slamming my brakes on a wet road. I went from ~30 MPH to a dead stop 3 times while letting the ABS do it's thing. I went back to the garage and re-bled the system and the pedal has felt better than ever!

[cuisinartvette]

Ive never been able to activate the ABS, even on a pretty aggressive canyon drive a few weeks back. There were a few times when I imagine it should have some on (tailbraking, etc)and didnt.

Ill have to hose the street down this weekend and pizz the neighbors off.

Maybe that will help.