another brake issue...Help !
Thread Starter
7th Gear
Joined: Feb 2006
Posts: 7
Likes: 1
From: Richmond TX
another brake issue...Help !
I am sorry if this problem has been previously addressed and if so please point me in the right direction. My 1991 now has the best brakes it has ever had...but....pedal drops to the floor. New rotors, pads, ss lines, booster, now on 3rd oem master. The brake was high and hard until m/c replacement. I finally got power brakes and they work great...except for the pedal issue. This car has been bled, power bled, gravity bled and bled again. I have done everything I know and my mechanic is losing his hair over this. Any suggestions are appreciated.
Melting Slicks
Joined: Oct 2007
Posts: 2,310
Likes: 9
From: KB7TIF Ville NV
I am sorry if this problem has been previously addressed and if so please point me in the right direction. My 1991 now has the best brakes it has ever had...but....pedal drops to the floor. New rotors, pads, ss lines, booster, now on 3rd oem master. The brake was high and hard until m/c replacement. I finally got power brakes and they work great...except for the pedal issue. This car has been bled, power bled, gravity bled and bled again. I have done everything I know and my mechanic is losing his hair over this. Any suggestions are appreciated.
Thread Starter
7th Gear
Joined: Feb 2006
Posts: 7
Likes: 1
From: Richmond TX
Been there ..done that. Starting to think ABS but don't know anything about it. The car is not losing fluid anywhere. Car stops straight and fast...best brakes ever with no pull...just pedal that drops to the floor??
Last edited by rsnake; Apr 7, 2012 at 01:51 PM. Reason: added detail
Advanced
Joined: Aug 2000
Posts: 53
Likes: 0
From: Westmont IL
There is air somewhere between the master cylinder and the ABS unit. You might need some kind of diagnostic software to run the ABS pump. Just happened on my sons' Audi after he relocated the ABS module. Don't know how to do this on the Vette unfortunately!
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
rsnake,
I have found that also bleeding the ABS unit at all 4 connections using a Motive pressure bleeder helped remove air and improve my pedal travel. The ABS is actually a high point in the system that can trap air. Nothing I read in the FSM really talks about it but I did it anyway and did get some air bubbles out of 2 connection. I just used a towel around the connection to absorb the fluid or it can get messy. I also had the key turned to the on position to activate the ABS during the process. Don't know if that was needed or helped but did it anyway.
Rick
I have found that also bleeding the ABS unit at all 4 connections using a Motive pressure bleeder helped remove air and improve my pedal travel. The ABS is actually a high point in the system that can trap air. Nothing I read in the FSM really talks about it but I did it anyway and did get some air bubbles out of 2 connection. I just used a towel around the connection to absorb the fluid or it can get messy. I also had the key turned to the on position to activate the ABS during the process. Don't know if that was needed or helped but did it anyway.
Rick
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
IMO sounds like improper MC bleed procedure keeping air in the MC the whole time.
Tell me you bench bled the MCs?
I prefer doing it on the car with the rear end raised so that the bore of the MC is level to doing it in a vice.
Tell me you bench bled the MCs?
I prefer doing it on the car with the rear end raised so that the bore of the MC is level to doing it in a vice.
Thread Starter
7th Gear
Joined: Feb 2006
Posts: 7
Likes: 1
From: Richmond TX
another brake issue...Help !
Thanks to all...Yes all 3 m/c have been bench bled. The system has been power bled and gravity bled. I have run about 2 gallons of fluid through this car. Nothing is sticking..all calipers and pads are working properly. The brakes work ! Panic stop from 60 with no hands on the wheel produce straight quick stops...with the pedal on the floor. Trying to figure out how to bypass the ABS as I think I may have a bad relay/solenoid on the ABS. No code though. I also think that it must be the rear as if it was the front I would probably see a pull and I don't. Anyone have a spare ABS unit??
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