LJ93Z28GM

Deleted the ABS by using a third gen propotionating valve.

Car will not lock up the front brakes and stops poorly. Trying to figure out exactly why.

Possible conclusions that I have come to are.

Still possibly air in lines but very unlikely, pumped the whole system and then manual bleed them as well and no air seen.

The amount of fluid pushed out by a third gen master versus a 4th gen master might be different and not thus not pushing enough fluid out upon applying brakes.

Third is that the booster is bad and that I cannot apply enough force with out power assist working properly.

What do you guys think???

dreamer1q

I think you need to get the hell rid of that proportioning valve. I did this my self. I run my car straight off the master and it works like a charm. Another guy on here, Brady96Z I think, showed me how to do it. You basically use a distribution block on the front brakes to get them down to one line, and you attach that line to the REAR of the Master. Then massage the rear line to mate up to the FRONT of the master. Simple as that. You dont need that Proportioning valve. My car stops BEAUTIFULLY and I have had ZERO problems since I have done this. I even went so far as to tap in my Lineloc at the same time. Take it off, plumb it like above and you will just grin when you come up to a stop light.

Q

LJ93Z28GM

So you are telling me that you do not even use a rear proportionating valve that is adjustable either. You have it run right off of the master cylinder.

Your rears do not lock up? Sorry but No my cup of tea to run it with no way to regulate the rear pressures. If i cannot figure it out this way I will use an adjustable valve.

Bone Daddy

Dreamer1q is correct!

1) The third gen PV is not meant for the bias ratio's on a 4th gen car. That's your problem, I would lay money on it.

2) If you must have a PV (I like Dreamer have run nothing, as well as a PV) then use a WilWood or Russell unit and plumb it like Dreamer describes, but add the PV to the rear line somewhere. I also noticed you "milled" alot of your fittings? Metric line and fittings are sold everywhere that sells Edelman, Everco, or Weatherhead fittings. (mostly NAPA) I chose to run AN lines and braided with my new set-up, so even that was an option.

[/.2]

LJ93Z28GM

Looks like I will be going with aftermarket unit and redoing all the lines.

It is really no big deal I just thought it would be easier to use the PV but no luck I guess.

As for the fittings you would be suprised that no one really carries the fittings for bubble flares in metric sizes that I needed. I tried 6 stores.

The sizes were
10mm x 1.5
11mm x 1.5
12mm x 1.5
14mm x 1.5

RedHottG2

Is there a major diff. in the way it responds to stoping once you delete the ABS ? I have thought about doing it but I just don't know what to expect. I know it's kinna hard to describe the diff. on here, but any help is appreciated.

Bone Daddy

Nope, all you need is

2 X 11mm to 10mm adapters
2 X 10mm splitters
10mm line of various lengths
PV valve

All readily available if you know where.

dreamer1q

Correct, I am telling you I DO NOT use a valve and I have never locked up my rears unless I want them to lock up. The master regulates the rear for me. It is PERFECT

DWoodAudio

I guess I have a hard time understanding the logic behind some of these "modifications", but to answer your original question, the 3rd gen prop. valve is whats causing your problems. It was not designed for the brake system on the 4th gen cars.
My real question is why you feel the need to disable a fairly good ABS system? If its not working properly then the logical thing would be to repair the problem instead of junking the whole system. GM's engineers spent a lot of time and money designing the brake system to work as a unit, and while better pads will improve hard braking (mainly because they will resist the heat that heavy use generates), mucking up things like the ABS system and front/rear proportioning without access to a lot of sophisticated test equipment and facilities to see what results your changes are having are just going to make a good brake system a dangerous disaster.