Brakes! Help If you can!
Thread Starter
Racer
Joined: Aug 2000
Posts: 315
Likes: 0
From: Brushton NY
Brakes! Help If you can!
I'm stumped. 1982 vet. New Brake calipers/shoes/rear rotors/new master cylinder. I pressure bleed them. They are great..right to the top. 1 week later the pedal is spongy again...I can see no leaks. I can see no visual fliud loss. How in the hell is air getting in this system?? I'm ready to have a fit and fall in it!Hellppppppppppppppppppp!! :cuss
Safety Car
Joined: Jul 2002
Posts: 3,770
Likes: 3
From: St Louis MO
Re: Brakes! Help If you can! (catfishjack)
If you've been driving it then it might be the rotors being out of true. With the springs behind the piston in our calipers, an out-of-true rotor can turn the caliper into an air pump.
Brett :thumbs:
Brett :thumbs:
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: Brakes! Help If you can! (catfishjack)
Sometimes a little molecular physics is necessary to understand what is happening. Air is mostly just N2, just two atoms of nitrogen...very very teensie tiny molecules. Brake fluid is something like C4H9O2 or something like that...a fairly big complex molecule. Air can get into the system even if fluid can not get out.
Because of this there is no way to detect where air is getting into the system without using the proper procedure...which is why I post the following link for people that have problems with their brake systems:
http:67.116.80.82/Vette/BrakeHelp/BrakeHelp.html
Briefly you need to use the brake pedal to pump the brakes and watch the fluid come out through a clear hose connected to the bleeder. That way the pedal will release the pressure in the line and allow air to get sucked back in, then when you press on the pedal again the air will be pushed out through the clear hose and you will see where the air is getting in...it's usually the calipers or the line connections. Anyway, you will be able to find out which line the air is getting in and trouble shoot until the problem is diagnosed and then solve it.
Because of this there is no way to detect where air is getting into the system without using the proper procedure...which is why I post the following link for people that have problems with their brake systems:
http:67.116.80.82/Vette/BrakeHelp/BrakeHelp.html
Briefly you need to use the brake pedal to pump the brakes and watch the fluid come out through a clear hose connected to the bleeder. That way the pedal will release the pressure in the line and allow air to get sucked back in, then when you press on the pedal again the air will be pushed out through the clear hose and you will see where the air is getting in...it's usually the calipers or the line connections. Anyway, you will be able to find out which line the air is getting in and trouble shoot until the problem is diagnosed and then solve it.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: Brakes! Help If you can! (catfishjack)
For right NOW, hell with all the chemistry, just take the silly springs out from behind the caliper pistons...front and rear...
and check the runout to see if it's really excessive super easy....jack up the car and run each wheel by holding the pads close to the rotor....one at a time...rears need engine on and in gear...at idle in first gear...rear needs held up by the suspension/arms....NOT the frame...take the wheels off and put the lug nuts on to hold the rotors on the hub....if you feel a LOT of runout..meaning side to side motion in the rotors...pads moving in and out...you need to true up the rotor...IF you don't...just take the springs out and be done with it....
take them out anyway..you can get away with a LOT there without those silly springs....
GENE
and check the runout to see if it's really excessive super easy....jack up the car and run each wheel by holding the pads close to the rotor....one at a time...rears need engine on and in gear...at idle in first gear...rear needs held up by the suspension/arms....NOT the frame...take the wheels off and put the lug nuts on to hold the rotors on the hub....if you feel a LOT of runout..meaning side to side motion in the rotors...pads moving in and out...you need to true up the rotor...IF you don't...just take the springs out and be done with it....
take them out anyway..you can get away with a LOT there without those silly springs....
GENE
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
Re: Brakes! Help If you can! (mrvette)
If your going to go to the trouble to take out the springs, better go ahead and upgrade to O-Ring pistons. The stock pistons and seals are useless.
