Rear brake drum performance

[Bentley]

Been thinking about this post....
You are either not getting enough flow or enough pressure it seems to me... Of course this is assuming you have the right shoes and wheel cylinders...
Did this problem start after the new parts??
I think I would disconnect the brake line on the pass side firewall ( at the union nut) then with someone pumping the brakes see how much fluid and pressure you have there.....
If OK there, reattach it and remove the hard brake line where it attaches to the soft line for the rear end...
Again if OK there, remove the soft line from the 2 lines on the housing and check flow and pressure there....
Just my thoughts here.... Something is not right, and I think this might help you figure out WHERE the problem is....

[fgross2006]

I cleaned mine out when I gutted it. I just used clean brake fluid and brake cleaner.

Any nylon or brass bristle brush that fits will work. Small tooth brushes included. Do enough to get it clean but don't go so far that you're removing material as brass is pretty soft. Hand power should be fine for this.

If I remember right there's a stud on the bracket that goes through the sheet metal and it's retained with a nut on the wheel side.

Circling back to the original concern, were the drums ever measured and confirmed to be in-spec? Also, was the master cylinder push rod length checked and verified to be correct?

The drums were installed new on my last rear brake job and they were smooth enough to not need a cut. As for the master cylinder I dont know. I never thought there was a rear brake problem until I tried hitting the brakes with the rear ties off the ground, so as far as I know this may have been an issue I was not aware of prior because the car does stop on a dime.

[qikgts]

10-4. I hear ya.

[fgross2006]

well this was one of the worst ideas I ever had. It was a total cluster F.

The instructions posted on the seller page look easy enough. He even has a video showing how to assemble, but not how to disassemble the proportion valve.

First, the brake lines were froze and my mechanic had to cut 2 of them just to free the proportion valve. I took it home and torched the lines and eventually got them all free. Then I got the piston and spring out, but the piston on the other side is frozen solid. I eventually ruined the threads trying to pick it out with needle nose pliers. Even if I can repair the threads and seal it with a strong thread locker, the piston is still in there solid. it rotates but wont pull out and I mutilated the end of it too. Not sure if it can be re rounded with sandpaper or if it will function as its supposed to.

Also, another thing, on the spring side the end plug on mine has a rubber nipple that's inserted down into the hollow of the plug. Instructions said to immerse all parts in ammonia, Should have known that this would weaken the only seal he doesn't supply with the kit. I see other proportion valves don't have that rubber nipple. I wonder if I can permanently plug that with something solid?

One last attempt to get the brass shaft out by putting grease fittings and trying to hydraulic pressure it out. Even if I do get it out, I'm not sure I can salvage this valve. My car is taking up a bay in my mechanics shop and he expects me to have the valve rebuild and ready to install Saturday morning. Not a good situation.

Just out of curiosity, I know there's some difference in the functionality of proportion valves, but this looks identical to mine, why would this not work?

https://www.amazon.com/WFLNHB-Propor...07336630&psc=1

[qikgts]

That sucks... However, your grease idea is a good one. I watched a video where someone did that on a prop valve.

Right now if I was you, I'd get an aftermarket adjustable proportioning valve, a union, and a brass t fitting and whatever adapter is needed and plumb it up so it can move and have brakes.

http://vb.foureyedpride.com/showthre...ortional-valve


Then later on, I'd start watching ebay for a NOS one or cheap used one to try and rebuild. At least these items are relatively inexpensive. Maybe not super cheap on the NOS valve but...

Since that Amazon one is so cheap, you "could" buy it and take it apart and start comparing dimensions to see just how different it really is from the OE one. I wouldn't be shocked if it turned out you couldn't tell the difference dimensionally or performance wise. But it is brakes we're talking about so you gotta do what you feel comfortable with.

BTW, I found a link to what I think is the same valve you linked to and it shows the port sizes. Thought that might be helpful.

https://speedandperformanceparts.com/products/pv6070fd/

You're not the first around here to have these issues...

http://vb.foureyedpride.com/showthre...-Lines-!/page3

[Bentley]

That last link in qikgts's using the Wilwood valve (Post #63) seems an option if you cannot find a replacement..
https://static.summitracing.com/glob...1179_cz_xl.jpg

Claim was it bolted up and the threads were all the same?
Worst scenario is I think you found your problem..

My 83 has all new brake lines, MC, calipers and rear drum pistons..... I think I will try gravity bleeding my car ( after bench bleeding the MC) to fill all of the lines and parts to hopefully prevent my distribution valve from moving...
Lots of successful gravity bleeds in the past with these NON abs systems......

[fgross2006]

That sucks... However, your grease idea is a good one. I watched a video where someone did that on a prop valve.

Right now if I was you, I'd get an aftermarket adjustable proportioning valve, a union, and a brass t fitting and whatever adapter is needed and plumb it up so it can move and have brakes.

http://vb.foureyedpride.com/showthre...ortional-valve


Then later on, I'd start watching ebay for a NOS one or cheap used one to try and rebuild. At least these items are relatively inexpensive. Maybe not super cheap on the NOS valve but...

Since that Amazon one is so cheap, you "could" buy it and take it apart and start comparing dimensions to see just how different it really is from the OE one. I wouldn't be shocked if it turned out you couldn't tell the difference dimensionally or performance wise. But it is brakes we're talking about so you gotta do what you feel comfortable with.

BTW, I found a link to what I think is the same valve you linked to and it shows the port sizes. Thought that might be helpful.

https://speedandperformanceparts.com/products/pv6070fd/

You're not the first around here to have these issues...

http://vb.foureyedpride.com/showthre...-Lines-!/page3

I took the proportion valve to my local machine shop and my friend there set up a temporary zerk and pumped grease into the valve. Surprisingly it pumped grease through the stuck piston but didn't pump it out. When he smacked it on the work bench it jarred loose and we were able to pull it out with needle nose pliers.

The seller is good about replying to emails. he said the end of the piston with the flat head screwdriver slot is so you can push the piston in with a screw driver. As long as the sections with O rings are intact, the mutilated end wont hamper the function of the valve.

A few things not quite right with the kit though. It shows a spring retainer pictured. Mine didn't come with one and there wasn't an old one in my valve to re-use so I just put the spring back in the way it came out.

Also, there was one O ring too large for any part of either piston. I think it belongs to the 87 to 93 kit. And I needed one more tiny o ring that wasn't in the kit so I had to re-use an old one that didn't look too bad.

Lastly, my proportion valve has a seal the protrudes through the end cap like a rubber nipple. Not only was that not in my kit, the seller told me today that he sells that seal separately for $3. I mean come on, he couldn't sell that as a $15 kit and include the nipple seal? The kit costs $12. Not super expensive, nor is the extra seal for 3 bucks. But finding out after I got my parts and have the valve disassembled was a kick in the nuts. I was not happy with that explanation.

I discussed this with my guy in the machine shop. Most every proportion valve we saw online have a sealed end cap. The seller says its a "weep hole". But as far as I'm concerned, a brake system is sealed and under pressure. I don't trust a weep hole and I didn't want to wait a week for another seal to be mailed to me, so I closed the top off with JB weld. Any thoughts on this? No going back, what's done is done so I'm committed to the build and I'll hopefully find out Monday if it worked out.

One last thing, the sellers instructions were effusive about protecting the yellow anodized finish on the aluminum valve. It wasn't possible to prevent some getting rubbed off with all the wire brushing I had to do so I primed it with aluminum primer then painted it black.

[qikgts]

If I haven't ever before, I commend your stick-to-itiveness. Nobody around here can say they haven't learned something from at least one of your bouts with Mustang heartburn.

You certainly ironed out the kinks with what to buy to do the whole thing. And I agree that the seller should just package it together, prompt you to order it, or at the very least mention it on the product page. Same with the reset tool.

Just nitpicking your comment above... Our brake systems are not "pressurized" or "under pressure". The mc moves fluid and because of restrictions pressure is the result. I think the rubber seal in the cap is there because when the proportioning valve starts working the extra fluid that's in/winds up in the valve has to go somewhere. Other prop valves have similar plugs in them too. A solid plug is used when using a AM valve and the stock assembly has been gutted.

I think your gut instinct is correct though in that you don't want leaks or contamination in the system as that's the reason for having to do the rebuild in the first place, but how not using that seal effects actual operation in the end, I don't know.

[fgross2006]

If I haven't ever before, I commend your stick-to-itiveness. Nobody around here can say they haven't learned something from at least one of your bouts with Mustang heartburn.

You certainly ironed out the kinks with what to buy to do the whole thing. And I agree that the seller should just package it together, prompt you to order it, or at the very least mention it on the product page. Same with the reset tool.

Just nitpicking your comment above... Our brake systems are not "pressurized" or "under pressure". The mc moves fluid and because of restrictions pressure is the result. I think the rubber seal in the cap is there because when the proportioning valve starts working the extra fluid that's in/winds up in the valve has to go somewhere. Other prop valves have similar plugs in them too. A solid plug is used when using a AM valve and the stock assembly has been gutted.

I think your gut instinct is correct though in that you don't want leaks or contamination in the system as that's the reason for having to do the rebuild in the first place, but how not using that seal effects actual operation in the end, I don't know.

Thanks, I have undertaken some fun and frustrating mods on my 84 LX convertible. The longest ordeal was setting up the rear quarter window guides from LMR. I had the entire rear interior out for 2 weeks. Spent inordinate time adjusting, testing and re adjusting.

Anyway, here's pics of my finished project.

I can only cross my fingers and hope it works OK, otherwise I'll have to try either an aftermarket proportion valve that looks right but is supposed to be for older model Fords, or an adjustable valve.

This is the proportion valve both front and back views, primed and painted satin black.





This is the plug end that I filled with JB weld. I have to think this wont be a big issue. Many proportion valves that are for disk/drum setups have a solid plug so I'll have to wait and see if this is a problem or not. Also, I'm 90% sure I threaded that plug in correct, but you have to apply pressure to push the spring back in while also making the threads. It turned tight but never felt natural or cross treaded to me. I used a 2 foot ratchet to get leverage and turned it in slowly till the o-ring was mashed.

The other side I mutilated the threads trying to get the piston out. My machine shop friend said as long as it tightened and holds torque its a good fit. I used locktite red on the threads just because of the condition and the brass washer did mash. I could keep applying pressure and turn more but I felt it bottom out and I don't want to push it further and strip it out totally. This will either fly or crash. I'll post after we've had a chance to install and test the brakes.



One last thing, this ebay seller is posting a stock proportion valves he says is for 84-86 SVO. Not sure why the SVO would have any drastic difference, but this guy wants 600 bucks and that a deal dead on arrival.

The real annoying part is that Frank N Stangs, a seller I have bought from in the past, was selling the exact same thing for $77. I was dissuaded when I saw it was for an SVO, but now I'm annoyed that I didn't just buy the thing when I had the chance. he sold it.

https://www.ebay.com/itm/12600942651...6517&recoPos=1

[Bentley]

85GTGuy, did you notice the OP's curly cue lines are like yours?

[qikgts]

I wouldn't use that SVO piece on a disc and drum set up. SVO has discs front and rear and the bias front to rear is much different than any other Fox. Way more in the rear.
'84 to '86 SVO- 200 psi split / .28 slope

Others that are solid data...
'81 Mustang/Capri 2 way alum. 300 psi /.28 slope
'80 Mustang/Capri, Fairmont/Zephyr 3.3L, 4.2L, 2.3L Turbo 300 psi split / .28 slope
'87 Mustang - All engines 300 psi split / .28 slope
'87 to '93 Fox (Unknown Engine)- 300 psi split / .28 slope

I just found that NPD sells a prop valve (The Delco type, that's the other common one you see floating around with a different shape and round mounting holes) that they advertise as being compatible. Maybe they can tell you the split and slope or if you dig around maybe it's out there somewhere.

[85GTGuy]

85GTGuy, did you notice the OP's curly cue lines are like yours?

Yes, exactly like mine. Did you end up making some?

[Bentley]

Yes, exactly like mine. Did you end up making some?

No not yet, it has been way too hot to do anything,,, I give it 3 hours in the AM and call it quits...
Exhaust, frame connectors and and the new " dual exhaust" brake line has had my attention, besides my home stuff...

I wonder if the Factory bent them like that so they knew which one went were when assembling the car??

[fgross2006]

so here's where I am with this project; I went to pick up my car today, my mechanic says that the rear brakes are holding pressure much better than before and with the car on the lift the rear wheels stop when brakes applied. Yay.

He also says that the stock low brake fluid sensor leaks brake fluid out the top through the 2 pins that the dongle plugs into. He left the brake bleed set screw in place until I can find another one of these. I cant locate a repro or a NOS, anybody have suggestions? I'm assuming when they torched the proportion valve trying to loosen the lines, that plastic sensor melted internally. Just out of curiosity, is the post supposed to move on a spring load? Mine can be pushed in, and it pops out, not sure it's supposed to do that.



But, it gets worse. After being told I'm good to go, as soon as I start the car, brake pedal to the floor. I go back in and tell him and he want's me to bring it back tomorrow morning and he will look it over again. In the meantime, I looked it over.

The two lines he cut to free up the proportion valve have been repaired with unions and they are holding and not leaking. The one line that did come loose after torching it, was the front brake line. I can see dripping falling off that line. I have flair wrenches and I gave it a quarter turn and it took it, but any more and I risk stripping out the internal thread on the proportion valve. I'm thinking the threads are leaking and allowing air back in. I'm leaning towards asking him to make a new flair and join to the line with another union.



Also, the set screw that holds the piston while bleeding the lines, I was under the impression there was not supposed to be any brake fluid in that chamber. Not only does the sensor leak through the pins, the set screw isn't fully holding either. Its juicy, not dripping bad but seeping.

[qikgts]

He also says that the stock low brake fluid sensor leaks brake fluid out the top through the 2 pins that the dongle plugs into. He left the brake bleed set screw in place until I can find another one of these. I cant locate a repro or a NOS, anybody have suggestions? I'm assuming when they torched the proportion valve trying to loosen the lines, that plastic sensor melted internally. Just out of curiosity, is the post supposed to move on a spring load? Mine can be pushed in, and it pops out, not sure it's supposed to do that.

There's likely nothing wrong with the switch. It's supposed to move, that's how it shorts the two terminals together.

Also, the set screw that holds the piston while bleeding the lines, I was under the impression there was not supposed to be any brake fluid in that chamber. Not only does the sensor leak through the pins, the set screw isn't fully holding either. Its juicy, not dripping bad but seeping.

If there is brake fluid in that chamber it will leak out through the switch. That means o-ring(s) failure on the pressure differential rod, it isn't sealing.

[fgross2006]

There's likely nothing wrong with the switch. It's supposed to move, that's how it shorts the two terminals together.


If there is brake fluid in that chamber it will leak out through the switch. That means o-ring(s) failure on the pressure differential rod, it isn't sealing.

Thats what I was thinking. If the o rings dont seal the low fluid switch then the rebuild failed and I'm back to square one.

I looked into NPD and they list this. It says it fits 65-73 Mustang but it also fits 79-86 Capri. How different can it be for an 84 Mustang?

It has to be better than what I got now. Sucks I went through all this trouble for nothing though. And if its a fail, I blame to kit. I wasn't getting leakage through the brake fluid switch prior.

[85GTGuy]

There's likely nothing wrong with the switch. It's supposed to move, that's how it shorts the two terminals together.

If there is brake fluid in that chamber it will leak out through the switch. That means o-ring(s) failure on the pressure differential rod, it isn't sealing.

Yea, agree 100% with what he said.

Thats what I was thinking. If the o rings dont seal the low fluid switch then the rebuild failed and I'm back to square one.

I looked into NPD and they list this. It says it fits 65-73 Mustang but it also fits 79-86 Capri. How different can it be for an 84 Mustang?

It has to be better than what I got now. Sucks I went through all this trouble for nothing though. And if its a fail, I blame to kit. I wasn't getting leakage through the brake fluid switch prior.

I'd be careful (and actually reluctant myself) to use a proportioning valve that isn't spec'd for your car. Although, it is very odd to me that that valve is listed for the 79-86 Capri, but not for the same year Mustangs.... don't know of any differences in the brakes between the two, but I'm not nearly as versed in Capri's, vs fox Stang's. There is that whole split value and slope value thing to do with prop valves though.... but that is above my pay grade (reference the linked thread). I think gutting your existing valve and adding an adjustable prop valve would be the safest route now. But that Capri valve from NPD sure would be enticing also. (Note they mention that they have no control over which side of the valve the mounting studs are on!)

http://vb.foureyedpride.com/showthre...PV-Valve-specs

[fgross2006]

Yea, agree 100% with what he said.





I'd be careful (and actually reluctant myself) to use a proportioning valve that isn't spec'd for your car. Although, it is very odd to me that that valve is listed for the 79-86 Capri, but not for the same year Mustangs.... don't know of any differences in the brakes between the two, but I'm not nearly as versed in Capri's, vs fox Stang's. There is that whole split value and slope value thing to do with prop valves though.... but that is above my pay grade (reference the linked thread). I think gutting your existing valve and adding an adjustable prop valve would be the safest route now. But that Capri valve from NPD sure would be enticing also. (Note they mention that they have no control over which side of the valve the mounting studs are on!)

http://vb.foureyedpride.com/showthre...PV-Valve-specs

actually an adjustable proportion valve would be useless at this point. The original is supposed to stay attached for the front brakes and the low brake fluid switch function. If the o rings inside failed and it leaks into the chamber for the brake light switch then the old valve is useless to keep.

[85GTGuy]

I'm talking about keeping your existing prop valve, gutting it, plugging the switch hole (which means, yes, you would lose the low fluid indication) and installing an adjustable prop valve at the firewall union (which is where they are typically installed). Or am I missing something? (which is entirely possible!)

Or just give that NPD valve a shot....

Or how about what @Two86fiveoh's did in post #2 of the linked thread....

http://vb.foureyedpride.com/showthre...plumbing-issue

[fgross2006]

I'm talking about keeping your existing prop valve, gutting it, plugging the switch hole (which means, yes, you would lose the low fluid indication) and installing an adjustable prop valve at the firewall union (which is where they are typically installed). Or am I missing something? (which is entirely possible!)

Or just give that NPD valve a shot....

Or how about what @Two86fiveoh's did in post #2 of the linked thread....

http://vb.foureyedpride.com/showthre...plumbing-issue

The only reason I did this job was because my rears were not locking up. According to my mechanic, the rears are now getting great pressure. If I'm sacrificing the brake light sensor, i can keep the proportion valve and plug the port the sensor goes in.

The seller of the kit offered to sell me a new piston, brake light sensor and brass sleeve. At this point I lost all interest in working this angle. I'm in the hole not just for parts, but I've paid my mechanic to experiments and I'm not gonna keep tinkering with trying to fix my valve.

Honestly I'm kind of pissed about this kit and the poor instructions and the lack of intuitiveness for possible different applications. I just noticed that the valve he uses in the printed instructions had the dimple gasket removed. There's no mention of it in the instructions or in his YouTube video. Check it out, there's a hole where the dimple plug should be and its not a threaded port. How about a disclaimer? "If your valve has a rubber dimple on one plug, you will need this extra gasket for an extra $3". Or, "you may or may not have a brass sleeve inside of your valve, here's 2 O-rings, one for each possible application".



And I'm in total disbelief that the pictured kit shows a brass sleeve that not only doesn't come with the kit, but no explanation as to why mine not only doesn't have that sleeve, but actually had a small O-ring in the groove where the brass sleeve sits. I ended up with one O-ring too large for that groove and I had to repurpose the old one, which may be why its failing.

No, I'm done with playing with this valve. I'm gonna plug he port the brake light sensor goes to and if the brake work I'm leaving it that way for awhile.

One last rant, I noticed driving this morning that my temp gauge isn't working. Is that tied into the brake sensor wiring at all? Or is that a side effect to my last project when I had the dash off to re wire my volt gauge? My speedo cable wont stay connected either. Second time I have to pull the cluster for that.

[qikgts]

One last rant, I noticed driving this morning that my temp gauge isn't working. Is that tied into the brake sensor wiring at all?

No. It is not.

[Bentley]

No, I'm done with playing with this valve. I'm gonna plug he port the brake light sensor goes to and if the brake work I'm leaving it that way for awhile.

I think if I was where you are, I would try this myself.... Remember that until 1967 this type of valve was NON existent in cars....

[fgross2006]

so this is where it ended up.

The leak was the brake bleed set screw. Removed it, put in a plug and washers and now its sealed. Brakes re bled, holding pressure now. It sucks to lose the brake light sensor but it is what it is. I tested the car and it stops on a dime. It's raining here in NY so I tested the hard stop on wet road and the brakes feel great so I'm leaving this for now. I am gonna pick up an aftermarket proportion valve because its just 40 bucks and if its not a good fit I can go back to what I have. But that's for another day. I'm keeping it this way for now.

Cautionary tale for anybody thinking about doing this. Expect to be off the road for a stretch of time. expect the kit may not be a perfect match for what you have and assume it will be difficult to disassemble the valve. Also don't be surprised that after all that effort, it still doesn't work or leaks internally.

When I get around to swapping the proportion valve I'll report back as to how it works.

[emerygt350]

You should be able to get a pipe thread plug for that screw. What a mess.

[1984GTTurboVert]

Its a shame you are still having issues with your prop valve.
Ironically it was a year ago today i replaced mine because the car had no brakes and were unbleedable.





I bought a nos one because it was the only option that was bolt in.
Thinking back i shouldve replaced the lines too since i was already there and i mangled and rounded the passenger side fitting taking it off.
I remember the svo one is different enough it wont work correctly.
I was under the impression the 83-86 v6 tbird prop valve was identical to this one, mounting bracket and all.