Swapping proportioning valve for "T" fitting... Options

[Wanna9146]

I read on this forum recently about someone swapping out their proportioning valve for a "T" fitting.

Does anyone know the size/thread count of the correct "T" fitting? Any fabrication required?

[sww914]

I wouldn't automatically blame the proportioning valve yet. If you've just rebuilt the calipers, replaced the pads, and turned the rotors, you will often have a somewhat spongy pedal for a while. The pads and the rotors are not yet making full contact on their faces because they need to wear into each other a bit, and the caliper pistons will need to smash through the paint and/or insulating material on the back of the pads. The just replaced calipers may also not be sitting perfectly true and square due to little bits of grit or corrosion on the mounting surfaces, but they will work their way into a solid position after some use.
Also, you didn't mention having gone through the fun process of adjusting the air gap on the rear pads for the parking brake, if that's maladjusted it will give you a long pedal. If the pistons in the calipers are clocked at the wrong angle, the high part of the lip on the piston will push more on one side of the pads than the other, as it's designed to, but in the wrong spot, thus wearing the pads unevenly. This should be corrected as it will shorten pad life significantly and it will take longer to get a firm pedal until the pads have worn flat to the rotors which would be at an odd angle in relation to the brake pad backing plate.
As you can see, there are several potential problems that a tee won't address.

[Wanna9146]

I wouldn't automatically blame the proportioning valve yet. If you've just rebuilt the calipers, replaced the pads, and turned the rotors, you will often have a somewhat spongy pedal for a while. The pads and the rotors are not yet making full contact on their faces because they need to wear into each other a bit, and the caliper pistons will need to smash through the paint and/or insulating material on the back of the pads. The just replaced calipers may also not be sitting perfectly true and square due to little bits of grit or corrosion on the mounting surfaces, but they will work their way into a solid position after some use.
Also, you didn't mention having gone through the fun process of adjusting the air gap on the rear pads for the parking brake, if that's maladjusted it will give you a long pedal. If the pistons in the calipers are clocked at the wrong angle, the high part of the lip on the piston will push more on one side of the pads than the other, as it's designed to, but in the wrong spot, thus wearing the pads unevenly. This should be corrected as it will shorten pad life significantly and it will take longer to get a firm pedal until the pads have worn flat to the rotors which would be at an odd angle in relation to the brake pad backing plate.
As you can see, there are several potential problems that a tee won't address.

The pedal is beyond "spongy". It goes almost to the floor. The car will only stop after some pumping and there is no way it will lock-up the brakes for a sudden stop.

I'll dismantle the proportioning valve and inspect/clean. That's really the only thing left that hasn't been addressed. Perhaps it is preventing a full bleed...?

[r_towle]

The pedal is beyond "spongy". It goes almost to the floor. The car will only stop after some pumping and there is no way it will lock-up the brakes for a sudden stop.

Dont take this the wrong way.
You have not bled the system.
Know that the proportioning valve is adjusted at the factory. keep track of how far in the set screw it...how many turns.

BUT
Try this first, please.
Crack the line that goes from the master to the proportioning valve.
Bleed it there first.
Then, once you remove the large air bubble in that line (trust me there is one)
you will have a better time with the remaining air in the system.

What happens is that you probably introduced alot of air when you changed all the parts...the bubble in the main feed line to the back of the car is the largest bubble that you need to get out.

Also, you need to set the venting in the rear brakes or you will never have a firm pedal.

Rich

[Wanna9146]

Thanks, I'll give this a shot.

BUT
Try this first, please.
Crack the line that goes from the master to the proportioning valve.
Bleed it there first.
Then, once you remove the large air bubble in that line (trust me there is one)
you will have a better time with the remaining air in the system.

What happens is that you probably introduced alot of air when you changed all the parts...the bubble in the main feed line to the back of the car is the largest bubble that you need to get out.

Also, you need to set the venting in the rear brakes or you will never have a firm pedal.

Rich