golfclubguy

Last Summer I replaced my master cylinder, I bled the brakes using the 2 person method....Pedal was rock hard for about 2 weeks then slowly started to deteriorate. Jacked the car up examined all the wheels for brake fluid/leaks there was none, the master cylinder was still full, but the front reservoir fluid was cloudy. So while it was jacked up with the wheels off I bled them again...with the same result, good for about 2 to 3 weeks. The only thing I noticed was possible/slight evidence of possible fliud at the caliper end of the brake hose...they are rubber and original..It's got me baffled...Any Ideas??? Car is a 79...


[Modified by golfclubguy, 9:12 AM 3/26/2004]

wombvette

Rear Rotors have runnout. You will need to get them to run true.

GTR1999

First replace the hoses,if they aren't bad they will be soon. They swell on the ID of the hose which can lockup the caliper.
The you have to be sure the rotor runout throught 360* is less then .003" at each wheel. Some will say .005" is ok but I wouldn't leave it at that on my cars or friends cars. Look at the rotors for warping or scoring if they are ok then you have to check the bearing settings. On the front they aren't bad to do. You should check the archives for recent post by Norval on settign the front bearings. The rear bearings are another story, they will take some tiem to check and even more to replace if needed. You cannot adjust the rear bearings on the car. You can adjust the runout though by placing shims in between the rotor and spindle flange.
I suggest you take a goodlook at the car brake system,check the runout,check to see if the rotors are still riveted on the hubs and spindles and see what you find.
Good luck, take your time and you'll fix the problem.
Gary

73 Vet

I've got the same problem with my '73. How much run-out is too much? Is it only the rears that effect this? I've replaced the master cylinder, replaced the rear rotors and on and on, but still run out of pedal after a few days.

Van Steel

rear rotors should be 5 thou or less.

Barry's70LT1

Just to clarify, with the rear rotors, it's not usually the rotor that is at fault.
If the bearing is fine (no excess play), then the next likely cause is the rear spindle flange.
Very often they are not true. You can have new rotors and still have runout due to the flange surface on the spindle.
History---- When made, the rear spindles/rotors are a matched set, riveted together when made. Over the years the rotor wears out and a new rotor is installed. That's when the problem starts.
The spindle/rotor are no longer a matched set.

To determine this, you need a dial indicator and check the rotor runout with the rotor attached to the spindle.
If more than .003, you will need to shim the spindle flange surface.

A more permanent fix is to have the spindle flange surface trued up at a machine shop.

Lots of information in the archives regarding this topic.
Barry