Fleetwood Proportioning Valve

[Adam]

The brake light has been on for a while. I am unable to "reset" the internal lockout through conventional means. Fortunately, I have a whole Caprice work of parts to leverage. Also, I'm due for a sticker next month, so the brakes should probably work correctly.

There's one catch, though. I modified the Caprice's proportioning valve to better work with the 4-wheel disk brakes that the 9C1 has. GM's "bean counters" decided that the 9C1 and Impala SS weren't worthy of making a separate valve for, so they ran the front disk-rear drum valve in them unchanged. Fortunately, for 9C1/SS owners, the aftermarket has stepped up and come up with some parts that eliminate the front brake apply-delay. Read about it here:
http://www.impalassforum.com/vBulletin/ ... -bolt.html

In order to use my 9C1 modified proportioning valve, I need to undo this modification.

Here is the as-removed valve after I disconnected the lines. You can see most of the original removed internal parts above.

Some close up comparisons of the original vs. modified parts. Original on the right, modified unit still installed.

Original unit on the left.

The removed parts should go back in somewhat like this.

It was a little bit of a pain to get the seal back into the bore, but I'll know if it works pretty quickly. Plus, I will have the one out of the FW to try to free up the internal shuttle switch if this one leaks. Success or failure stories later.

[kevm14]

Does the Fleetwood use the same proportioning valve?

[Adam]

Yes. All the GM listings I found have the same GM PN 10223533 listed for all B/D body applications.

[Adam]

Check the application list at the bottom of the page.

http://www.gmpartsgiant.com/parts/gm-va ... 23533.html

[Adam]

Well, the new valve is in. Results: inconclusive.

The old valve's shuttle switch was definitely tripped. I was able to reset it by removing the switch and using a screwdriver to push the switch back to where it normally sits. So that was definitely a problem. I was then able to bleed the front brakes and got some air out.

However, the light is still on and the pedal feels too stiff. In addition, it seems like the rear brakes are still not releasing. They smelled hot after the drive back home. Sigh. I was unable to bleed the rear brakes due to the bleeders not moving and me running out of time (daylight?).

So maybe I have multiple problems? I think I might need to replace the rear wheel cylinders (again) as last time I was dealing with the rear brakes, they were unwilling to easily retract. Unless that was the proportioning valve. Or there is an issue with the ABS unit. There is a bleeder on that too I should try to use.

One thing's for sure: the Fleetwood is way faster than the Accord, even if it can't stop correctly.

[kevm14]

How about a master cylinder issue?

[Adam]

How about a master cylinder issue?

Possibly. I have already replaced it during my ownership, though.

[Adam]

AZ sells this:
http://www.autozone.com/brakes-and-trac ... 48463_0_0/
Since everything came apart easily yesterday, I should be able to do this on the car.

[kevm14]

Is it possible that the master is not releasing fully? This is a little bit of a reach but when I swapped vacuum boosters (from a 95 9C1), I created an issue where the master would not fully release. It did not expose the return ports and I had a brake drag issue and a very firm pedal. It wasn't until I took it back apart and realized that the pushrod that the booster used to actuate the master was longer than the one I had. I think I ended up grinding down the end until the master could fully retract. My memory is now a little cloudy because the master that is on my car now came from a 96 9C1 and I think I actually had this issue with the 96 master cylinder...I know, confusing. I have pictures somewhere of my original 93 pushrod and probably the one from the 95 9C1.

I think one way to diagnose is to crack the bleeder when the brakes are dragging. Most likely fluid will come out since it was under some pressure. Of course that just means something isn't allowing the brake fluid to return to the master cylinder. As you said, the ABS is in the loop there, along with the proportioning valve and master cylinder.

One thought: create the brake drag issue by driving the car. When you get home, jack up whichever end is dragging (I think you said the rear). Then loosen the master cylinder to booster nuts and see if that releases the rear brakes. When you reinstall the master, you should be able to mate it flat against the booster, and not have to use the nuts to get it flat.

[Adam]

Good point. I had to undo the master cylinder yesterday in order to remove the proportioning valve. I don't think it sat completely flat...

If that's the case, I could modify the pushrod. Stupid aftermarket junk. I suppose just cracking the bleeders and letting the pressure out might "fix" it enough. I should see what the brake code is.

Another thought: I have a whole 4-wheel disc rear end. I could do a rear disc conversion and go back to the bolt upgrade kit. With dual 3/16" lines, that is more fluid delivery area than a single 1/4" line split between the two sides so fluid delivery wouldn't be an issue.