Proportioning valve Tool J-22742

[dieselpilot]

Has anyone found a source for the J-22742 brake proportioning valve bleeder tool shown in the factory shop manual and required to correctly bleed front disc brake calipers? I have a 1975 front end on a 1967 truck. Thanks

[FORDification]

If you didn't want to use a small pair of ViceGrips to hold that pin out, I would think it would be easy enough to fabricate your own tool out of a piece of thick tin.

[dieselpilot]

Good call on the vice grips. I think I`ll try both solutions- it shouldnt be hard to make a comparable tool. Thanks Keith!

[Alvin in AZ]

Yeah I found a source, I made one out of 1/32" thick 1095 steel from Brownell's. ;)
http://www.panix.com/~alvinj/file12/bleedtool.jpg
The watch-spring-blue is from "drawing" it to that color after quenching it from ~1500F in quenching oil.

The tool doesn't do anything tho! :/
It holds the pin out fine, easily overcoming the internal spring.
But what the heck for?
It seems to make no difference at all in the bleeding operation. :/

http://www.fordification.com/board2/pro ... eeding.jpg
I have that same picture in my '75 Ford Shop Manual. :)

If you've found that it makes a difference, please explain it to me! LOL :)

Alvin in AZ
ps- I could make these things if there was a real need for them.

[cdeal28078]

I have never used one or done anything but bleed the front calipers the normal way and my brakes work GREAT. Better than some newer trucks I would bet.
Is it just to keep from turning on the brake warning light above the parking brake? That is what I figure it is for.
clint

[FORDification]

I have never used one or done anything but bleed the front calipers the normal way and my brakes work GREAT. Better than some newer trucks I would bet.
Is it just to keep from turning on the brake warning light above the parking brake? That is what I figure it is for.
clint

No, that button is for bleeding. According to the '72 shop manual, when discussing bleeding the brakes on F250 trucks with front discs:

"It is necessary to depress the bleeder button on the metering valve when bleeding the front brakes. This is to allow the brake fluid to reach the caliper assemblies. This operation is particulary important if pressure bleeding equipment is being used."

http://www.fordification.com/board2/bra ... ding01.jpg
http://www.fordification.com/board2/bra ... ding02.jpg

Granted, this is for bumpside-era trucks which had a separate disc-brake metering valve, apart from the standard distribution block which incorporated the pressure differential switch. However, the only difference between this setup and the dentside-era proportioning valve is that the dentside piece just combined these two pieces into a single unit. It contains a shuttle valve that separates the front and rear brake pressure circuits, and activates the pressure warning switch. It also contains a pressure metering valve for the rear brakes, to reduce hydraulic pressure to the rear drums, preventing rear wheel lockup during hard braking.

However, that button that you pull out is part of a built-in 'delay' for the front discs, which give the rear drum shoes time to overcome the brake shoe return spring pressure and travel out to the drum surface, theoretically allowing all four pads/shoes to start braking at the same time. The delay is necessary because the pads on the front don't have anything pulling them away from the discs...they're basically riding (very lightly) on the disc surface, so they're ready to be applied, whereas the drum shoes have to actually travel a slight distance before contacting the drum surface. Without the delay, the front discs would be braking way before the drums, resulting in an unbalanced setup that would usually cause the vehicle to come around during a panic stop.

So...as you can see from the diagram above, there is a spring behind that button. This spring temporarily resists brake fluid pressure to the front calipers until additional pressure is applied to overcome it. Not pulling out on the spring will prevent (or at least greatly diminish) fluid from reaching the front calipers during bleeding.

That's my understanding of how it works anyway...but I've been wrong once or twice.

[Alvin in AZ]

Keith, carefully reading your post I believe I understand what's going on. :)
Really cool post, BTW. :)

The Ford Shop Manual suggests using a tool because "they figure" a
dealership will tend to use pressure bleeding equipment. Don't know,
but that equipment, with its pressure, may seal-off the proportioning
valve and actually prevent bleeding.

Shade tree mechanics -like me- have never ran into that problem? :)

Anyway, I've got the tool and it didn't seem to effect bleeding at all.

Alvin in AZ
ps- I made that tool only about 12 years ago just to see what it'd do. ;)
Nuthin'. :/

[FORDification]

More pressure isn't going to close or "seal off" anything....actually just the opposite.

Bleeding the brakes manually, with someone sitting on the driver's seat pushing on the brake pedal, creates a great deal of brake line pressure. Line pressure can vary between 800-1000 psi minimum during an average stop to more than 2000 psi during a very hard stop...enough to overcome that delay spring and open the front brake circuit. On the other hand, a pressure bleeder (typically, just an air pot) only produces 80-100 psi worth of pressure, which isn't enough to overcome the delay spring. That's why they say it's especially important to manually open it when pressure-bleeding.

So how much pressure did you have to exert on that button to open it and insert the tool anyway? Any idea?

[Alvin in AZ]

So how much pressure did you have to exert on that button to open it and insert the tool anyway?

Not... very... much. ;)

The tool bends closer together about 1/8" with medium pressure.
It's 5/8" wide and 1/32" thick spring-tempered 1095 drawn at ~650F, twice for a few minutes.
It is plenty stout to hold the button out, against the internal spring pressure, that I can tell you for sure. :)
If you get a chance to pull on one of those buttons you'll have some idea how much it takes.
This homemade tool easily doubles that. :)

A proportioning valve is one thing I've never taken apart and that by itself is odd as anything,
because I love taking things apart. LOL :)

Alvin is a tinkering fool in AZ

[Banjo]

I didn't want to take time to build a little metal spring clip thingy to bleed mine, so I pulled the little spring thing out with something (can't recall now, likely pliers) and locked the tip of the smallest needle nose vise grips I have on there (to keep it open). It was still too large and I guess, being concerned about getting too tight with the jaws and "marring" some surface that shouldn't be, they fell off a time or two. I think i'll make a little clip like that during the winter when I have less to do. But, I'd sure rather fine one in a helps section at a chain store for $5 or so. Banjo.