ok here's the background:
68 Charger - originally big manual drum all around.
went w/ the Scarebird disc conversion for the front brakes. Got all new rotors, calipers and hoses, all to mount on the stock drum spindle.
Kept original manual drum proportioning valve and hard lines (actually, new lines, but exact repros).
replaced the master cylinder with one of those alluminum Mopar units with the black plastic reseviour. Bench bled it before mounting. Don;t remember what bore size, but I bought it new from Rick Ehrenberg on Ebay.
Same as this:
I also bought 2 new rear drum wheel cylinders from Rick - his listing mentions something about the lack of a residual pressure valve in modern master cylinders which necessitates using these rear wheel cylinders to avoid a spongey pedal - they were cheap, so i bought them.
Lastly, I bought an inline adjustable proportioning valve and mounted it in the hard line going to the rear brakes - right under the driver seat under the car.
So, I have it all hokked up, and nothing is leaking. Problem is, I CANNOT get a firm pedal. I've bled the brakes and in a few sessions have gone through probably 3 big containers of brake fluid - in the master cylider, out the bleeder into the cup, and into the trash.
The fron calipers seemed to bleed fairly easy - no bubbles after just a few seconds or so. The rears are a dfferent story - the rear driver seems to have an endless supply of air in it. BTW - I'm using a vacuum pump to bleed. I thought maybe air was getting in behind the bleeder, so I loaded grease all around it to seal it up as I bled - no dice - still getting air.
The result is a brake pedal that is spongey, and on 2 occasions - while backing the car into a storage garage, the pedal went to the floor with no resistance. Funny thing is that it did that only 2 times, and at the same exact place, doing the same exact thing - backing the car in the storage garage - only thing I can think that is unusual about that is that the car it tilted with the front end down as it enters the garage - other than that, it's just a spongey pedal.
Is there air getting in my brake lines? If so, why is there ZERO leaks when I inspect it, and when the brakes are used - I would think using the brakes, the pressure would make a leak fairly obvious.
I went as far as getting a second set of the rear wheel cylinders and replaced the driver's rear and re-bled - no improvement.
Help.
68 Charger - originally big manual drum all around.
went w/ the Scarebird disc conversion for the front brakes. Got all new rotors, calipers and hoses, all to mount on the stock drum spindle.
Kept original manual drum proportioning valve and hard lines (actually, new lines, but exact repros).
replaced the master cylinder with one of those alluminum Mopar units with the black plastic reseviour. Bench bled it before mounting. Don;t remember what bore size, but I bought it new from Rick Ehrenberg on Ebay.
Same as this:
I also bought 2 new rear drum wheel cylinders from Rick - his listing mentions something about the lack of a residual pressure valve in modern master cylinders which necessitates using these rear wheel cylinders to avoid a spongey pedal - they were cheap, so i bought them.
Lastly, I bought an inline adjustable proportioning valve and mounted it in the hard line going to the rear brakes - right under the driver seat under the car.
So, I have it all hokked up, and nothing is leaking. Problem is, I CANNOT get a firm pedal. I've bled the brakes and in a few sessions have gone through probably 3 big containers of brake fluid - in the master cylider, out the bleeder into the cup, and into the trash.
The fron calipers seemed to bleed fairly easy - no bubbles after just a few seconds or so. The rears are a dfferent story - the rear driver seems to have an endless supply of air in it. BTW - I'm using a vacuum pump to bleed. I thought maybe air was getting in behind the bleeder, so I loaded grease all around it to seal it up as I bled - no dice - still getting air.
The result is a brake pedal that is spongey, and on 2 occasions - while backing the car into a storage garage, the pedal went to the floor with no resistance. Funny thing is that it did that only 2 times, and at the same exact place, doing the same exact thing - backing the car in the storage garage - only thing I can think that is unusual about that is that the car it tilted with the front end down as it enters the garage - other than that, it's just a spongey pedal.
Is there air getting in my brake lines? If so, why is there ZERO leaks when I inspect it, and when the brakes are used - I would think using the brakes, the pressure would make a leak fairly obvious.
I went as far as getting a second set of the rear wheel cylinders and replaced the driver's rear and re-bled - no improvement.
Help.
