Okay.. here goes.

I put my car up for the winter, so I could install my new rear end, ls1 fuel pump, and a host of other goodies I'd bought. When I removed the rear of course I had to remove the brake lines and such from the rear, fluid was leaking out, but I capped the rear line at the body with a hose and clamp and it appeared to stop. The car was left apart for several months as rear ends are not cheap in the least, and it was winter after all.

When I reinstalled the rear end and went to bleed the brakes, I found the master cylinder and lines empty (wasnt when leak was "stopped") After a good bleeding or two, the new peddle feel was terrible, went near or to the floor. After about 3 bleeds, I finally thought the new stainless lines might be taking in air. The stock rubber/brass lines cut into the brass washers when they are installed, these didn't.

Replaced them with new GM hoses, and bled, which brought my peddle feel up to descent standards, but not near as stiff as I remembered them before the rear-end removal.

I drove around for a month or two mostly content, until a week ago. I decided to replace the front pads as to me they looked fairly thin. So, I bought pads for the front. I depressed the pistons and installed the pads. When I had finished the final set up, (driver side) I noticed fluid dripping off the fender mounts. I discover I'm an idiot, and I've forgotten to take off the cap on the master cylinder. I cleaned all this up, and drove a few trips each time there was less and less fluid on the master cylinder, I figured this to be blowback from all the fluid that might have ran into cracks after coming out the cap. (It has not since leaked any fluid from anywhere since) Anyway after the pad install, the peddle feel went back to crap, and sometimes seemed to have good feeling at first then when I was down the road it would cut about or close to.. in half. Start car/good feel, drive a few miles/crap. Lather rinse, repeat.

I bled them thouroughly again today, and even went so far as to put new rear pads on . There was NO air in the system, (I even had a flashlight to the bleed hose). I did not do a test drive (its raining like all hell today and im testing brakes?..eh no), but the car seemed in idle to have intial descent brake feel, then got kinda crappy after so many pumps, which had been a problem since the pads. This time I took the cap off, and did it properly, thank god.

Did my master cylinder get dryed out when it accidentally drained?

Did not using a scan tool during bleeding jinx my brakes since the rear end?

Do I have a broken seal(s) in the master, even though it shortly stopped "leaking" (fluid on the master's surface and booster) after I cleaned it properly?

Could my booster valve or booster had picked a crappy time to go bad?

My brakes havent felt right, even before I might have damaged my Master, what was the old problem?

All I want is the feel it had before the rear-end swap, dagnabbit.

 

Having the master cylinder dry didn't hurt it.

ABS brake systems have all sorts of passages that take awhile to get bleed right. I recently did the same thing while swaping the rear and had the same problm to a lesser degree.

Take the car to a garage that has a pressure bleeder and have the brakes bleed including the ABS block. If this dosen't fix it, there is something else wrong.

 

Thanks for the post.

I've hand bled it (no pun intended) at least 6 times a wheel, and pressure bled, even after buying/using solobleeds (Earl's) and now that the rear brakes are installed, I just test drove it. It's "close" to where it was before the front pad install. I've now went through about 3 gallons of fluid in all. Is there a way to manually and without the scantool, to agitate the abs box plunger or w/e so that I can make sure once and for all? Haynes manual and the dealership tech mentioned something about it, but I didn't see him do it. (im friendly with all the staff at my local stealership) I've bled other ABS systems and never had this problem, so hope it's not a F-body issue.

I did a search on several forums and it seems consistancy with braking force after idle, is a master cylinder issue. I think either you're right about the ABS, or the master is bad. It did have fluid on the booster where it meets the master cylinder, but since I haven't seen anymore since, I hope it was blowback like I was thinking earlier.