My front brakes (both of them) locked up on me the other day, all the hardware was checked and rechecked including new lines, but after a test run where the brakes locked up again, it was traced to a bad proportion valve. Where can I find one for this truck with the 390 V8 and disc front and drum rear (stock brake set up)? LMC doesn't have anything, Summit has a universal one, and none of the local parts or chains carry it calling it a dealer only part. Call the two Ford dealers near by, they never heard of it. The truck is a 74 F-100, surely I am not the only one to have to replace this part. Anyone else might know of one or if you replaced yours with an aftermarket which did you use and what did you need to do to make it fit?

 

I quote myselves:

Follow my build thread: https://www.ford-trucks.com/forums/1...ide-build.html

 

If you want to stick with OEM parts:
Valve, Brake pressure differential valve
73-74 F100 2WD w/ disc brakes
D3TZ-2B257-A
Marked D3TA-25254-AA

I located one,
Wesley Obsolete Parts, Liberty, KY shows 1 in stock (606) 787-5293

 

whatever you do, do not get the brass one made by MBM. They all fail at the same point, the plastic disc in the bleeder pin.

 

Summit has told me that the one from Classic Performance should fit with replumbing the lines. We are probably going to replumb the lines anyway, I am just needing to make sure that what I get will work. I would have thought someone would have kept making these things along the way.

 

Sorry no help, but Holy crap HIO...I almost want to burn down my rigs when I have to straighten 4" of tube for a new fitting. I can appreciate the beauty in those brake lines.

 

X2, nice work HIO

 

Dangit... I was going to offer the new one I have to replace the one that failed within a month.

Seriously.....get the Wilwood

 

Thanks....just imagine if I had a good attitude about brake lines. Sometimes I scare me.

 

I believe Inline tube carries them... that said are you sure your rears aren't weak causing the front lock-up? Visual inspection, bleed and adjust on the rears wouldn't hurt.

 

@HIO Silver I tried sending you a private message because after the reading I've done through the forum tonight you seem to know a lot about this part, but the forum said you had too many messages already(lol) so I decided to just reply in this thread. First the problem; my dad took his 74 F100 to a shop to have some different parts installed including the front flexible brake lines. He took it to a shop mainly because it would be easier for them to bleed the system once everything was installed. Well after installing the parts and driving the truck the shop told me at first the calipers we sticking on the front. I went by there after work that day and the way they explain it is if the truck sits a while you can jack up either side and the front wheel will spin freely, but if you hit the brakes one time it makes the tire next to impossible to turn. While I was at the shop they told me it's either the calipers or the proportioning valve. I asked them to do some more checking to narrow down the problem to see how we want to proceed. They called me today to say it needed a proportioning valve and that they couldn't get it of course. First, does the proportioning valve sound like the problem? The truck is a 74 F100 two wheel drive Ranger with the 360 engine. Second, if the valve is the problem do you suggest the Wilwood like you used and if so is it possible to hook up the brake light in the dash? I read some reviews on Summit about people liking the ease of the brake light wiring, but I'm not sure they are talking about the one in the dash or something else. I saw that some sort of harness comes with the valve so I just wanted to ask. Any insight you can give me will be helpful and I'm hoping you'll see this soon since I'll probably have to make a decision tomorrow on what I'm going to do and get some parts ordered. Thanks in advance!!

 

Yeah my bad. I gotta clean out my PM box. Thanks for the reminder.

In terms of the sticking calipers, yes it could be the prop valve or the booster if equipped with power brakes. A bad booster will sometimes not release the vacuum after a couple of brake applications. Only after time has elapsed and the vacuum bleeds off will the brakes "unlock". I ran into that issue with my 2WD '70...

The issue could also be the prop valve. The proper way to bleed the system is to hold its internal in position with a special tool. See, if one end of the brake system (front vs rear) fails, an internal pressure imbalance occurs and the piston slides towards the low pressure side (the end that is leaking). The piston has a detente (or saddle) in which the brake pressure warning light is connected to.. when the piston is actuated, the brake switch's pin slides up out of its saddle, closes the brake warning light circuit, and the dash light illuminates.

The switch at the end of the Wilwood prop valve is a brake switch that operates the brake lights - not the dash light. On my Bump, I deleted the pedal-actuated brake light switch, extended the wiring, and use the Wilwood switch for the brake lights.

I am of the opinion that the OEM prop valve is troublesome... troublesome to bleed and impossible to rebuild because there apparently are no service parts available. A few members have attempted to do so by measuring and spec'ing O-rings but I have yet to hear of any success. Most will opt for a GM-style prop valve but my research indicates that most are made overseas and fail simple testing. If you're gonna get one, get it from a reputable parts house like Stainless Steel Brakes Corporation or Master Power Brakes... NOT Ebay where there is troublesome recourse to get a replacement or your money back.

For me, the Wilwood is a quality piece, made in the USA, and Wilwood has a good reputation in high performance brake products and very active in motorsports... that's why I went with it. The "loss" of a brake warning light doesn't bother me.. it's a small price to pay for dead nuts performance.

Hope that helps your decision...

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