brake problems
Thread Starter
Intermediate
Joined: Nov 2002
Posts: 30
Likes: 0
From: Friendswood Texas
brake problems
My '74 will not keep a brake pedal. I have replaced all four calipers, pads master cylinder, flex lines including all of the steel lines on the front. The system can be bled to accomodate a decent brake pedal, but within a couple of days the pedal drops and everthing gets soft. eventually I get the red brake light on the dash. I have bled this system probably 10 times. I always get the same results. I did read that if the rear wheel bearings were out of spec. that this would cause a air pumping action within the calipers, which i nturn allow air into the system. I find that hard to believe. Help!!!
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: brake problems (bmizell)
YES, it unfortunarely the pumping of air into the system....i'ts due to the springs behind the pistons in the calipers, IF you can feel the runout with the car jacked up and on stands in the rear....spin the rotors....engine start, car in gear....lock into first...feel the brake pads, if you feel any side to side runout...it's probably too much for stock pistons....
so you have a 1/2 day's worth of work....pull the dust boots, remove the pistons and springs, and then reinstall everything without springs....
OR buy new O ring pistons all set up and ready to go...removing the O rings is ok on the old lip OEM type seals also...I ran my car for over 4 years of daily use like that...
GENE
so you have a 1/2 day's worth of work....pull the dust boots, remove the pistons and springs, and then reinstall everything without springs....
OR buy new O ring pistons all set up and ready to go...removing the O rings is ok on the old lip OEM type seals also...I ran my car for over 4 years of daily use like that...
GENE
Tech Contributor
Joined: Aug 1999
Posts: 15,124
Likes: 3,927
From: Connecticut, USA
Re: brake problems (bmizell)
I would first check the runout on all the rotors. You should have less then .005",.001-.003" is preferred. If everything else is new and correctly installed then dial in your runout and you should be ok. Did you have the rotors turned? If so then you might have helped create the problem in the rear system. Check the runout and work from there.
Gary
Gary
Melting Slicks
Joined: Mar 2001
Posts: 3,365
Likes: 5
From: Lake Villa IL
Cruise-In IV Veteran
Cruise-In V Veteran
St. Jude Contributor
Re: brake problems (bmizell)
Check out my website. I have full pictures to help you O-ring the calipers and bleed the brakes easily.
I had the same issue. Remove the springs and O-ring the calipers. Your problems will go away. Plus, it's a cheap mod ($30 a wheel).
I had the same issue. Remove the springs and O-ring the calipers. Your problems will go away. Plus, it's a cheap mod ($30 a wheel).
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: brake problems (bmizell)
Vette Brakes here have the new pistons and O rings, and seals....
leave out the springs, your problems are history....unless you rear rotors are really gross, then they knock back the pads too far, and the amount of fluid it takes to clamp down on the rotor again is a bit much....
GENE
leave out the springs, your problems are history....unless you rear rotors are really gross, then they knock back the pads too far, and the amount of fluid it takes to clamp down on the rotor again is a bit much....
GENE
