Issues with pedal while running

[laidbackbigun]

Okay a little run down
1. 1995 tahoe removed abs junk and replaced with a proportioning valve from a 1992 c1500.
2. Replaced all lines front and rear, replaced all brake components except master cylinder and brake booster.
3. Disc front drums rear.

Heres the issue. Engine off pedal is firm almost to firm. Engine on and i get a pedal that travels almost all the way to floor. Stops truck but doesnt feel right. Pedal is real soft. Ive bled these brakes so many times i felt like reusing the fluid i caught in my bleeder jug. Ive vacum bled and old school bled. No air shows at all.

Halp!

 

[Dubs]

Okay a little run down
1. 1995 tahoe removed abs junk and replaced with a proportioning valve from a 1992 c1500.
2. Replaced all lines front and rear, replaced all brake components except master cylinder and brake booster.
3. Disc front drums rear.

Heres the issue. Engine off pedal is firm almost to firm. Engine on and i get a pedal that travels almost all the way to floor. Stops truck but doesnt feel right. Pedal is real soft. Ive bled these brakes so many times i felt like reusing the fluid i caught in my bleeder jug. Ive vacum bled and old school bled. No air shows at all.

Halp!

You might be dropping vacuum. Do you have a vacuum Gauge to test?

 

[laidbackbigun]

You might be dropping vacuum. Do you have a vacuum Gauge to test?

I.can check at work, but wouldnt it be a hard pedal when running as there is no "assist" from the vacuum

 

[Dubs]

I.can check at work, but wouldnt it be a hard pedal when running as there is no "assist" from the vacuum

Its hydroboost yes?

 

[RichLo]

unfortunatly, its probably the master since you have eliminated everything else.

Edit: Unless you accidentally installed the calipers or wheel cylinders on the wrong sides and have the bleeder valves on the bottom?

 

[Dubs]

unfortunatly, its probably the master since you have eliminated everything else.

Id double chech the proportioning valve. You sure you took it off a 92 with rear drums? When i did my bisc swap i had to take the oring off the piston for the rear. To my understanding if you do it with drums you get soft pedal.

 

[laidbackbigun]

Its vacuum assisted not hydroboost.
The calipers and wheel cylinders are proper and up.
It could be master cylinder but thats what im trying to find out.
Yeah i checked vin and rearend on donor truck at junk yard. 1992 with rear drums.

 

[Dubs]

Its vacuum assisted not hydroboost.
The calipers and wheel cylinders are proper and up.
It could be master cylinder but thats what im trying to find out.
Yeah i checked vin and rearend on donor truck at junk yard. 1992 with rear drums.

It's not a hard job swapping mc. I got one off summit that was powder coated for $125. Tuff stuff I think was the manufacturer