I'm copying this post from the brakes forum to see if I can get any traction over here. Will also post in the '87 and up forum.

Let me know if I should gut the "Proportioning pressure regulating control valve"

Join Date: May 2009
Posts: 41
Tarheel Blue
'87 Master Cylinder
Quote:
Originally Posted by LARIAT 85 View Post
I have a 1985 Ford F-150 with a stock cast-iron master cylinder. I was wondering if I could replace the master cylinder with the see-through plastic master cylinder that started in 1987? Can I just replace the cylinder, or will I need to use a 1987 brake booster as well?

Was searching everything I could find about my next project when I ran across this old question by Lariat 85. I've started the process by getting a new booster (O'Reilley #54-74211) for an '85 and the MC ( O'Reilley NMC 4007) for an '87. All was going great until I couldn't find adapters to go between my existing '85 lines and the new '87 MC.
I figured out the easiest way to hook it back up with my original lines was to swap the flare nuts and grab a "proportioning pressure regulator control valve" (E7TZ2C161C) off of an '87 in the yard so that the threads match up.
My question is whether or not anyone has used this part, and if so, did you gut it or leave it fully functional.
I guess I'm worried that if left functional, it might react poorly with the stock Proportioning valve down on the frame.
What are your thoughts?
Attached Images

 

Looking forward to this discussion!

 

I thought I'd run across a post a while back where someone had gutted theirs but now I can't find it.

 

I'd like to know this as well. I'm sick of those heavy cast iron master cylinders that rust themselves to death. BTW, I like the color of your truck in your profile picture. Same as mine except the roof on mine is blue.

 

A little additional info;
The flare nut thread sizes on the original cast iron MC are
Primary - 9/16-18
Secondary - 7/16-24

'87 MC w/ plastic reservoir
Primary - M18-1.5
Secondary - 9/16-18

I was able to find an adapter to go from 7/16-24 to the 9/16-18, but could not find one to go from 9/16-18 to M18-1.5

What I did notice was that the "Proportioning pressure regulating control valve" that is used on the '87s has the M18-1.5 to 9/16-18 threads, so all I did was change the nuts on my existing lines.

It would seem that now I have two devices that want to regulate the primary and secondary pressures!

My concern is whether they will play nice or cause problems. I had read something a while back about gutting the valve that mounts on the MC, but not sure if I should and would like to hear some opinions.

 

Would it be possible to get the brake lines for an 87 up, or am I under thinking this?

 

You would still need to convert to the M18-1.5 that is in the MC as the '87 lines end in 9/16-18 and 7/16-24

 

I thought that since the MC has M18-1.5, that the lines would match

 

After lots of reading last night, it seems that I have the answer to whether or not I should gut the "Proportioning pressure regulating control valve". Here is an excerpt from the shoptech.com website and the first rule is what did it for me;

Proportioning Modifications

We could start this section by clearly stating that you should not modify your proportioning valve. But, what fun would that be? In all seriousness, making changes to the proportioning valve to effect brake bias should be left to those with the proper tools and measurement devices, but if you have tweaked your vehicle beyond recognition, this may be your only solution to restore a sense of proper bias to your braking system.
We’ll start here with three of the most basic rules regarding proportioning valve installation and selection.
1. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed if the factory unit is still in place. Proportioning valves in series with one another can do nasty, unpredictable things!
2. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed in-line to the front brakes. The effect would be to make your vehicle rear-biased before you could say “terminal oversteer.” Front brake line pressure should always be left alone – only the rear pressures should be considered for proportioning.
3. In all cases, the basic brake system balance needs to be close to optimized to start with. This is the only way that a proportioning valve can be effectively utilized. You should never assume that simply adding a proportioning valve will address all rear-bias conditions, as even the best proportioning valves must be well-matched to the target vehicle.


So, here is a pic of the valve that I pulled off of an '87



Here it is turn apart and the exploded view from Ford



And lastley, the stock '85 proportioning valve that I'm leaving on my frame rail.


The best thing about taking the adapter apart is that the first fitting (to the far left in the second pic) is simply a bushing that goes from the M18-1.5 to the 7/16-24 that my stock line has. I won't even need all of the rest of the parts.
I still need to get this all back together and bleed everything but I think all will be golden.
Stay tuned for a road test in the next couple of days.

 

How did this work out for you?
I'm thinking of doing the same with my '85 F-250.

 

The 87 system has a rear anti-lock brake system on it doesn't it? I believe that is why the 87 doesn't even have a "proportioning valve" but that weird little thing at the master cylinder that must work in conjunction with the rear abs braking system. Am I correct on that?

 

Rovernut, sorry but have been real busy w/ other stuff lately and haven't had a chance to work on the truck much. Last thing that I got accomplished was to bleed both rear brakes, but haven't gotten to the fronts yet. I'll post again once that's done and i survive a test drive

Franklin, I'm not sure about the anti-lock on the '87s. I do know that the description of the function of the device on the '87 MC reads the same as the description of the function of my '85 proportioning valve on my frame.

 

Were you ever able to finish this project? If so, I am interested in your findings.

 

Hey, sorry I left this thread hanging!
YES, absolutely works for me. No leaks, no rusty cylinder and I can see at a glance the fluid level. Love the mod!