Need brake help - getting very frustrated
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 8,762
Likes: 2
From: Murphy TX
Need brake help - getting very frustrated
Ok, here's the brief history
- hot track
- bad pad taper
- wierd pedal (would go all the way to the floor with the power on)
Got home figured it was the taper. Installed new rear pads, installed LG Wilwood front calipers, complete bleed...and I mean complete.
Went for a run to bed the new brakes and the pedal is still soft. I've bled like crazy, I do not feel there is any air in the lines, it feels like something else.
It is hard to describe, but the best I can do is this - the brakes feel like they engage at a normal pedal travel but it feels like I have to push a LONG way to induce heavy braking. I can achieve it, including ABS on dry pavement.
Another interesting symptom...while bleeding (all power off) when we let the pedal up you could hear a groaning noise coming from under the dash, i.e. as the master cyllinder was filling back up...
With power off the pedal is firm, which leads me to believe there is no air in the system. It's only when power is on.
Could this be a booster issue? Where is the vacuum for the booster?
Does any of this give anyone any ideas? I'm fixing to take it to the dealer, but with the new calipers I don't want them pointing to those first...sigh. I'm getting quite frustrated.
Thanks!
Jon
- hot track
- bad pad taper
- wierd pedal (would go all the way to the floor with the power on)
Got home figured it was the taper. Installed new rear pads, installed LG Wilwood front calipers, complete bleed...and I mean complete.
Went for a run to bed the new brakes and the pedal is still soft. I've bled like crazy, I do not feel there is any air in the lines, it feels like something else.
It is hard to describe, but the best I can do is this - the brakes feel like they engage at a normal pedal travel but it feels like I have to push a LONG way to induce heavy braking. I can achieve it, including ABS on dry pavement.
Another interesting symptom...while bleeding (all power off) when we let the pedal up you could hear a groaning noise coming from under the dash, i.e. as the master cyllinder was filling back up...
With power off the pedal is firm, which leads me to believe there is no air in the system. It's only when power is on.
Could this be a booster issue? Where is the vacuum for the booster?
Does any of this give anyone any ideas? I'm fixing to take it to the dealer, but with the new calipers I don't want them pointing to those first...sigh. I'm getting quite frustrated.
Thanks!
Jon
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 8,762
Likes: 2
From: Murphy TX
NO leaks whatsoever. Checked all that.
I am concerned about the master, although if I get on the pedal and hold it there it doesn't seem to bleed down...sigh.
Thanks for the replies.
I am concerned about the master, although if I get on the pedal and hold it there it doesn't seem to bleed down...sigh.
Thanks for the replies.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Here is where the BOOSTER gets its vacuum from:
The large rubber hose on the left is the booster vacuum supply. The fitting in the red circle is the vacuum supply nipple for your HVAC System and the AIR Injection control valve.
Unplug the fitting from the booster resovour with the engine off and you should hear the vacuum release.
BC
The large rubber hose on the left is the booster vacuum supply. The fitting in the red circle is the vacuum supply nipple for your HVAC System and the AIR Injection control valve.
Unplug the fitting from the booster resovour with the engine off and you should hear the vacuum release.
BC
Melting Slicks
Joined: Jan 2003
Posts: 3,251
Likes: 4
If it was the booster you would get grabby brakes with too much vacuum or very hard brakes with too little vacuum. I remember a thread just last month or two that had the very same issue. He bled the system with gallons of fluid and still no improvement. jeff jeff hit it on the head with the master. It's time to replace it. Nothing else would give those symptoms except air in the line and a soft flex line which does not seem to be the problem.
Last edited by IM QUIKR; May 7, 2005 at 10:46 PM.
