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Rear brake lock up/grab before fronts drum brake setup

I know in the USA, these valves were under recall in 2000 and 2001 where the complaints were rear brakes locking up before fronts and the valve had become corroded enough to get stuck either when it is used, or when it is at rest. Not sure if it can be unstuck with brake clean but they are no longer available anywhere, Have found they are available in the UK and found a set on ebay.
http://www.ebay.com/itm/BRAND-NEW-O...ash=item4195937081:g:IlIAAOSw6WdXig~I&vxp=mtr
 
'It takes 8 hours for the rears to go down to 100 psi when the brake is used for 30 minutes to one hour.'

Well, that certainly ain't right.

What we are thinking, as tests indicate, BOTH PCRV valves are stuck in the compressed position, where fluid can go to the wheel cylinders at the right pressure, but won't release to allow the pressure to go to 0 fast enough. However, these PCRV valves have been under recall and subsequent revisions of the valves still stick and keep the system overpressurized at the wheel cylinder. DOT is not going to allow the shop just replace the valves, since it is a safety issue; and the car must be inspected by WSP before it is allowed on the road.
 
How is it DOT is even involved with car, that seems rather odd.
 
I'm also a little confused here as to why (Washington?)DOT and the Washington State Police are involved. I can see it's a safety issue, but the shop should be able to perform the work, as is outlined below, road test the vehicle and deem it safe to be driven.

There was a recall campaign on these brake pressure valves, initiated by NHTSA in March 2000.

Early 1996 vehicles with the PCRV's on the master cylinder were not affected, vehicles with the PCRV's on the brakes lines in the rear wheel wells were affected. The issue was with corrosion of the PCRV's, a newer PCRV with a weather boot was released as part of a kit from Ford, XS7Z-2C477-BA, which contained two new design PCRV's. The associated Ford Service Recall Bulletin is "Safety Recall 00S03".

I'm not aware of any recall of the revised PCRV's that were provided in kit XS7Z-2C477-BA. If you have information about this that I don't have, please post a link, I'd like to see it.

partsvoice.com shows a fair number of these kits in stock at various Ford dealers around the country, search the part number without dashes, as XS7Z2C477BA.
If these kits were under a subsequent recall beyond the initial safety recall, they would have been purged from dealer stock.

I believe because this is a safety recall, and not an owner notification program (ONP) or TSB, there should be no expiration date and Ford should provide this service to you at no charge, but I've been wrong once or twice in my life.

The Ford safety recall bulletin 00S03 can be downloaded here. (clicky for a pdf download)

March 9, 2000 NHTSA Campaign Number: 00V075000
FORD/REAR BRAKE VALVE IF BOTH PCRV'S MALFUNCTION, VEHICLE HANDLING COULD BE ADVERSELY AFFECTED DURING BRAKING AS A RESULT OF THE REAR WHEELS LOCKING, INCREASING THE RISK OF A CRASH.
NHTSA Campaign Number: 00V075000
Manufacturer FORD MOTOR COMPANY
Components SERVICE BRAKES, HYDRAULIC
Potential Number of Units Affected 436,200
Summary
VEHICLE DESCRIPTION: PASSENGER VEHICLES NOT EQUIPPED WITH THE ANTI-LOCK BRAKING SYSTEM (ABS). A PRESSURE CONSCIOUS REDUCING VALVE (PCRV) IN THE REAR BRAKES MAY BE SUBJECT TO CORROSION AND RESULT IN MALFUNCTION, WHEN OPERATED IN AREAS THAT USE SALT COMPOUNDS ON THE ROADWAY FOR DE-ICING OR DUST CONTROL.

Remedy
DEALERS WILL INSTALL IMPROVED PCRV'S IN THE REAR BRAKE SYSTEM. THIS RECALL WAS EXPANDED IN SEPTEMBER 2000 TO INCLUDE 1999 AND 2000 FORD CONTOUR, MERCURY MYSTIQUE AND COUGAR VEHICLES.

Notes
OWNER NOTIFICATION BEGAN APRIL 3, 2000 FOR THE 1996-1998 MODEL VEHICLES AND ON OCTOBER 11, 2000, FOR THE 1999-2000 MODEL VEHICLES. OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT FORD AT 1-800-392-3673. ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S AUTO SAFETY HOTLINE AT 1-888-DASH-2-DOT (1-888-327-4236).

Vehicles
FORDCONTOUR1996-2000
MERCURYCOUGAR1999-2000
MERCURYMYSTIQUE1996-2000
 
I'm also a little confused here as to why (Washington?)DOT and the Washington State Police are involved. I can see it's a safety issue, but the shop should be able to perform the work, as is outlined below, road test the vehicle and deem it safe to be driven.

There was a recall campaign on these brake pressure valves, initiated by NHTSA in March 2000.

Early 1996 vehicles with the PCRV's on the master cylinder were not affected, vehicles with the PCRV's on the brakes lines in the rear wheel wells were affected. The issue was with corrosion of the PCRV's, a newer PCRV with a weather boot was released as part of a kit from Ford, XS7Z-2C477-BA, which contained two new design PCRV's. The associated Ford Service Recall Bulletin is "Safety Recall 00S03".

I'm not aware of any recall of the revised PCRV's that were provided in kit XS7Z-2C477-BA. If you have information about this that I don't have, please post a link, I'd like to see it.

partsvoice.com shows a fair number of these kits in stock at various Ford dealers around the country, search the part number without dashes, as XS7Z2C477BA.
If these kits were under a subsequent recall beyond the initial safety recall, they would have been purged from dealer stock.

I believe because this is a safety recall, and not an owner notification program (ONP) or TSB, there should be no expiration date and Ford should provide this service to you at no charge, but I've been wrong once or twice in my life.

The Ford safety recall bulletin 00S03 can be downloaded here. (clicky for a pdf download)

I got pulled over by a Puyallup Police Department officer on 12/16/2016 with a written defective equipment citation to get the car off the road and repaired before driving it. They were going to impound the vehicle because the brakes prematurely locked up going down a 35 degree incline hill, which requires the brakes to be applied, but I almost slid sideways into a ditch. The court is needing the car inspected by WSP/DOT before the car/ticket is allowed on the road and ticket reduced. Car was Red Tagged, meaning there is a sticker on the windshield noting the defective equipment in the brakes, and the car if driven without inspection can be impounded. I was going downhill at 35 mph and was trying to slow down to avoid collisions with a vehicle ahead of me who was also travelling the same direction, but slower than I was. It was at night and roads were dry. For the car to be driven, the shop will need to repair the braking system, then have WSP do what is called a visual inspection and performance inspection where the car is driven then stopped at 20 mph and 30 mph and distance measured to see if it stops within the allowed distance. I had the car flatbedded to the shop where they are in the process of redoing the lines to make it approved.

Ford no longer carries such parts, they were discontinued about 10 years ago because of known problems of them (recall and them sticking). I had Ford look up the revised part and even with the recalled part number, it is not available to the dealer. Ford suggests to remove the PCRV valves (because they are known to stick easy) and replace them with a proportioning valve that can be serviced. PartsVoice info is incorrect. I checked with each dealer and the part number and each one said the parts were discontinued with no availability.

Shop knows that part was recalled, but is not going to take chances replacing it with a like part due to the recall issue and amount of issues with them sticking. Shop is licensed for brake repairs and they also know that if they don't fix it to a perfect condition, they are legally liable if I hit someone and the brakes are the cause of the collision.

That recall only affects cars in areas where road salt is used heavily. WA state does not have the salt usage, where cars here were not covered under the recall. Mine has the original PCRV valve ahead of the rear wheel.
 
How is it DOT is even involved with car, that seems rather odd.

Being pulled over and cited for defective equipment will make it necessary for DOT to be involved, especially with brake systems. $240 fine plus impound fees if they deem it necessary to keep it off the road. I was about 1/2 mile from my house, and cop did follow me home to ensure I wasn't going to ignore the issue. I had it towed when the shop opened on the 19th.
 
Wow, what a pain in the ass. A proportioning valve acts somewhat differently than a pressure limiting valve, as a prop valve limits the pressure rate increase for the rear circuit to a different slope than the front circuit, rather than just capping the pressure increase as a pressure limiting valve does. I've installed adjustable prop valves in the rear circuit of two of my track cars that lack ABS, and sometimes the rear slope proportioning has to be adjusted as fuel load changes the rear weight.

Perhaps it's time for a new car?:wink:

Is it possible to get an early '96 master cylinder with the integral pressure limiting valves and do some cut and splice with the engine compartment brake lines to make that work?
 
Wow, what a pain in the ass. A proportioning valve acts somewhat differently than a pressure limiting valve, as a prop valve limits the pressure rate increase for the rear circuit to a different slope than the front circuit, rather than just capping the pressure increase as a pressure limiting valve does. I've installed adjustable prop valves in the rear circuit of two of my track cars that lack ABS, and sometimes the rear slope proportioning has to be adjusted as fuel load changes the rear weight.

Perhaps it's time for a new car?:wink:

Is it possible to get an early '96 master cylinder with the integral pressure limiting valves and do some cut and splice with the engine compartment brake lines to make that work?

Can't afford a new car. They are over what I can afford.

I've built brake systems before, and know how it needs to work. I designed and built the system used on my 68 Chev truck I and my students built about 20 years ago. That uses an adjustable proportioning valve so I can dial in the exact pressures to front/rear ends. On that I can adjust it so the ass end has more braking if I'm towing a heavy load, where trailer brakes need to grab first, or adjust it so fronts grab first.

I've been in contact with Ford engineers, who hate the design of the Contour and early Focus designs of the brakes. I don't like it either because the rear tends to lock up first, which in wet conditions, the car tends to end up sideways if the front-rear ratio is 50/50. That is what the cop had noted (he has had the early focus and had similar issues). The 96 masters won't fit. tried that already. I don't think rear brakes should be at an equal braking to the fronts, there should be a higher percentage of braking ratio to the front brakes than the rear brakes.

On the 96 vehicles, it uses the Focus PCRV valve, they are also not available either, and junkyard parts legally can't be installed by a shop. Laws here are quite strict on shops that repair the car brake systems and problems occur later. Here, the state requires shops to guarantee zero problems for a year after doing the brakes, and junkyard parts of brake components cannot be installed by a shop due to liability issues. Lawsuits can be a pain, but following the rules are necessary.

I'm very familiar with WSP inspections. I drive with hand controls and every time I install them on a car, I must get it inspected since I'm modifying the use of the car. The state wants to ensure the car is safe, road worthy (even new cars) and the controls do what they are designed to do. On that, I also must involve Federal DOT as well.
 
In the late 90s and 90's, when ABS was still optional, it was possible to specify a car that would end up as yours has, which is unfortunate. Ford had similar issues with Gen 1 and 2 Taurui, both rear disc and drum: They used a rear pressure control valve that was linked to the rear suspension and tried to compensate rear brake pressure based on ride height and rear load. It was... modestly effective when new and clean, but performance suffered as salt-belt cars started to corrode and undercar mechanics got cranky, or fell off. The ABS cars would compensate for it, but the non-ABS cars could be a handful on slippery roads

Though you have limited options, it seems you have the situation under control.

Best of luck to you.
 
In the late 90s and 90's, when ABS was still optional, it was possible to specify a car that would end up as yours has, which is unfortunate. Ford had similar issues with Gen 1 and 2 Taurui, both rear disc and drum: They used a rear pressure control valve that was linked to the rear suspension and tried to compensate rear brake pressure based on ride height and rear load. It was... modestly effective when new and clean, but performance suffered as salt-belt cars started to corrode and undercar mechanics got cranky, or fell off. The ABS cars would compensate for it, but the non-ABS cars could be a handful on slippery roads

Though you have limited options, it seems you have the situation under control.

Best of luck to you.

That is why I'm going for a more tried and true non ABS system with a replumbed hydraulic system. It took a while to pinpoint the issue, but designing the hydraulics from scratch is the best option. Not my first time modifying a car equipment to work correctly. In 07, I had a 07 Hyundai Elantra (I was working at the time) and had this odd rear squirm on the car that at 60 mph, the ass end tended to do in directions you didn't want it to go. At the time, dealer wouldn't touch it; apparently they knew it was a problem and were not going to admit it. Even had a engineer tell me that I had to redesign the rear suspension on my own to fix it. A patent later, I got an aftermarket company using my design and every time they sell the parts, I get paid. Having that patent on the design was a way to make A LOT of money.

Pressure valves stick. They need to be serviceable, Even ABS tends to do the same thing.
 
My '89 Taurus SHO non-ABS track car has a re-plumbed brake system. I changed it from diagonally split to front-rear split with a Wilwood cockpit adjustable prop valve in the rear circuit, the rear suspension bias valve was disabled and it became much more well behaved after that.

As an ex-Ford engineer, one of the biggest gripes I have with North American OEM's and their relationship to their customers is that brake fluid is some mysterious concoction with an infinite lifetime, and so unless a vehicle gets major brake service, the brake system is never bleed of old, water-contaminated fluid. I'm still stunned every time I raise someone's hood and see a master cylinder reservoir full of Black sh*t. I try to put a quart of fresh brake fluid through the systems of my daily driven cars on an annual basis, the track cars get fresh brake fluid far more frequently, and I've never had to replace calipers, master cylinders, or other brake components for internal corrosion.
 
My '89 Taurus SHO non-ABS track car has a re-plumbed brake system. I changed it from diagonally split to front-rear split with a Wilwood cockpit adjustable prop valve in the rear circuit, the rear suspension bias valve was disabled and it became much more well behaved after that.

As an ex-Ford engineer, one of the biggest gripes I have with North American OEM's and their relationship to their customers is that brake fluid is some mysterious concoction with an infinite lifetime, and so unless a vehicle gets major brake service, the brake system is never bleed of old, water-contaminated fluid. I'm still stunned every time I raise someone's hood and see a master cylinder reservoir full of Black sh*t. I try to put a quart of fresh brake fluid through the systems of my daily driven cars on an annual basis, the track cars get fresh brake fluid far more frequently, and I've never had to replace calipers, master cylinders, or other brake components for internal corrosion.

That is what the plans are for my car. I'm planning on going with a proportioning valve with a front-rear split system. However, I might have to change out the master cylinder which the non-ABS units have 4 output ports, where we would have to replumb the system where the front circuit handles both front brakes and have a Y connection to the proportioning valve which the rear brakes are connected to that.
 
I'm going to try to clean out the master cylinder and rear PCRV valves. I think what is happening is the pressure is building up and fluid can't return to the master reservoir as easily as it needs to. It only starts to lock up after driving for a while.
 
Long ago and far away I remember working on a friend's car with a rear caliper that was dragging and wouldn't release after the pedal returned, we pulled our hair out for quite awhile and finally traced it to a caliper flex hose that had a collapsed inner liner, it would open up when the brakes were applied, but when pressure was released, the inner liner would collapse and not let pressure out of the caliper.

On another thought, would doubling up the shoe return springs take away some rear brake bias?
 
Long ago and far away I remember working on a friend's car with a rear caliper that was dragging and wouldn't release after the pedal returned, we pulled our hair out for quite awhile and finally traced it to a caliper flex hose that had a collapsed inner liner, it would open up when the brakes were applied, but when pressure was released, the inner liner would collapse and not let pressure out of the caliper.

On another thought, would doubling up the shoe return springs take away some rear brake bias?

I'm going to first clean up the brake fluid first and run brake clean through the PCRV valves. It ONLY does it after driving for a while. When I first start out, it won't prematurely lock up, but after 20 minutes of driving it in stop/go traffic, it will start to grab, particularly the right side in the rear, but I notice the left front wants to tighten up at the same time.

I am going to look at the adjuster spring and see how much tension it has, and will try to bend the hook of the spring to tighten it up. I looked at the flex hoses and they appear fine.

It somewhat seems as the one circuit of the master cylinder wants to pressurize before the other. I know the fluid is contaminated. I flushed it quite a bit 2 years ago when I did the brakes then,

1. possible master cylinder circuit issue, or piston sticking where it is ok when I start out, but using the brakes for 10-15 minutes makes it overpressurized, but takes 7-8 hours to go down.
2. Sticky PCRV valves, but notice both valves operate normally until it gets pressurized for 15 minutes. Don't think they are sticking, but cleaning them out will help.
3. Weak adjuster spring, allowing the adjuster to expand tooo much, but again, it doesn't do it when I first start driving it.
 
I bled the brakes until the system has fresh fluid, but notice right rear tended to stick a couple times. That was the same side and corner I had trouble bleeding before. Got it to bleed more normally after about 3-4 times of flushing it. I notice that the :pCRV valve on that end and the other side was replaced at one point. Couldn't remove it to clean it with brake fluid.
 
Found the issue. Sticky master cylinder. As I somewhat ride the brake going downhill, it will tighten up. I don't really notice it on the drivers front, but that circuit seems to tighten up first, then it will also tighten up the other circuit as well, but much later. It seems as one of the pistons is partially blocking a return port and overpressurizing the one circuit by not allowing fluid to return as fast. Notice that the brake pedal seems to have a bit more play in it than I would like.
 
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