What happened to my brakes?!

[Mike93]

Out of nowhere this problem arose...

212,000 miles on the car. All calipers are new as of ~5000 miles, as well as rotors, and rear e-brake cables.

The other day, while driving home form work I noticed my pedal went to the floor before any braking set in. Once to the floor I have to put some serious pressure on the pedal to get stopped. I'd also venture to say I'm using a very small percentage of the brakes. The car will stop, it just takes some heavy pedal effort and a little more distance to achieve the stop.

On an abandoned road I tested a panic stop from 50 mph. Found that the car pulled hard to the left, and the back kicked to the right...felt like the car was pivoting/rotating right over the midpoint of the car.

Fluid level is full in the master cylinder. I can't find anything vacuum related that has gone bad...

Seems like a master cylinder, proportion valve, or brake booster issue...but I'm just guessing here.

Any thoughts???

 

[93rev2sev]

All new calipers.

That throws up a red flag.

Get the car up on stands. While running, Put light pressure on the brake pedal with a broomstick and use your electric seat to apply the pressure. Get out a prybar and try to turn your wheels using the lugs as leverage. You will find the culprit wheel if it's as bad as you say...it'll be the one you can turn.

 

[Mike93]

All new calipers.

That throws up a red flag.

Get the car up on stands. While running, Put light pressure on the brake pedal with a broomstick and use your electric seat to apply the pressure. Get out a prybar and try to turn your wheels using the lugs as leverage. You will find the culprit wheel if it's as bad as you say...it'll be the one you can turn.

I don't understand how them being new calipers can throw a red flag? It feels as if a bunch of air has entered the sytem...

 

[stangeater]

Sounds like a brake booster problem to me. Had that happen in one of our farm trucks. You had to put the brake to the floor, and it felt like they were the old manual brakes....no power brakes. If the new calipers have been fine for 5k miles, then I doubt they are the culprit. I'd check out the brake booster. Good luck!

 

[Mike93]

Sounds like a brake booster problem to me. Had that happen in one of our farm trucks. You had to put the brake to the floor, and it felt like they were the old manual brakes....no power brakes. If the new calipers have been fine for 5k miles, then I doubt they are the culprit. I'd check out the brake booster. Good luck!

What's the best way to test a brake booster? I have a boost/vacuum gauge...can I do anythiing with that???

 

[stangeater]

Honestly mike, I've never done it myself. I took our truck to a brake shop, and they replaced the booster for me. I'm not sure how you test it. I'm sure there is someone on here who has had that problem before.

 

[SHOZ123]

Power Brake Functional Test


Vacuum Booster

Inspect all hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections should be properly secured and in good condition with no holes or collapsed areas. Inspect check valve on power unit for damage.


Booster Operation Check

1.Check hydraulic brake system for leaks or insufficient fluid.

2.With transmission in NEUTRAL, stop engine and apply parking brake. Depress brake pedal several times to exhaust all vacuum in the system.

3.Depress pedal and hold it in the applied position. Start engine. If vacuum system is operating, pedal will tend to move downward under constant foot pressure. If no motion is felt, the vacuum booster system is not functioning.

4.Remove vacuum hose from brake booster check valve connection. Manifold vacuum should be available at the check valve end of the hose with engine at idle speed and transmission in NEUTRAL. If manifold vacuum is available to the booster, connect vacuum hose to booster and repeat Steps 2 and 3. If no downward movement of brake pedal is felt, replace brake booster.

5.Operate engine a minimum of 10 seconds at fast idle. Stop engine, and let vehicle stand for 10 minutes. Then, depress brake pedal with approximately 89N (20 lbs) of force. Pedal feel should be the same as that noted with engine operating. If pedal feels hard (no power assist), replace check valve and retest.

 

[Calypso]

Yeah, I had this same problem happen to me. I was driving down that highway at a smooth 75 mph and got on the off-ramp to discover I had no brakes. Downshifting helped that alot. Anyways, it turned out I had a VERY small leak that would pretty much leak only when I was braking. Doesn't seem like this is the problem with yours since your fluid level is fine, but it wouldn't hurt to check. The fluid in mine didn't noticibly drop right after that happened, either. Only after a little bit of driving/braking did it drop...

 

[TopGunnYFZ]

My 90 does this, if i push the pedal to the floor it will only have stopping power the last half inch, but if i pump it quick then push it again it will be like normal and lock em up. Any suggestions? This cars fluid level doesnt drop either.

 

[black935spdSHO]

sounds like you have a broken brake line to 1 or more of the wheels. check the fluid level in the resiovor. if its damn near empty theres your problem. you might not even be able to see the break in the line it could be a small pin hole. or onr of your new calipers may have stuck but i highly dought it. i would take the brake lines off all for corner and run new fluid thru the lines u may have some rust at the end of the lines and its causeing a restriction of fluid to the caliper. just a coulpe of ideas also im not sure if these cars have a metering vavle or a porportioning valve (basiclly the same thing) but this is where the flid is transfered to all 4 corners if this failes you might not be geting fluid to the front or rear or even left to right. it might be causeing the jerking from left to right in your panic stop. hope this helps.

ken

 

[smokekicsazz]

Whe I replaced my rear brakes and rotors I went to bleed them and I had a collapsed L/R hose!! Maybe you have a collapsed hose? Just a suggestion...

 

[Racer X]

My 90 does this, if i push the pedal to the floor it will only have stopping power the last half inch, but if i pump it quick then push it again it will be like normal and lock em up. Any suggestions? This cars fluid level doesnt drop either.

Mine is in the beginning stages of this, and I've replaced the MC already to no avail. I'm going to replace the ABS HCU next (for other reasons), but I'll see if there's a change in performance after that. If not, do they still sell brake boosters for the Taurus? Is the one for the SHO specific to the SHO?

 

[yzstud]

Mine is in the beginning stages of this, and I've replaced the MC already to no avail. I'm going to replace the ABS HCU next (for other reasons), but I'll see if there's a change in performance after that. If not, do they still sell brake boosters for the Taurus? Is the one for the SHO specific to the SHO?

If u feel the need to replace the hcu, then go for it. Just remember to have the entire car bled properly, master cylinder, hcu, and calipers

And yes brake boosters are available for the taurus, and no they are not specific, slo or sho, they are both the same depending on the years

 

[Joe_Cool]

Mine did something sort of like this just today.

There has been a slight vibration when I press the pedal, just once in a while for the last couple weeks or so. Drove it home tonight, and it was fine. I got dressed to go out, got in the car, and the pedal suddenly goes all the way to the floor and I have almost no braking power at all.

Fluid level is fine.

 

[nistah]

While you all are disussinig brakes, mine seem spongey & the sho has been drinking brake fluid, until the brake light on the dash comes on, I'll top it off with brake fluid and the light goes out only to come on a few days later and then the resoviour seems low again, is this a leak at one of the brake the lines, how urgent is the need to replace, dont want to be coming off a highway ramp and find out, oh S$*# no brakesl, input appreciated thanks,

 

[SHOZ123]

I changed my ABS module out on my '97 and did not need it bled. I don't know if the Gen 2s are the same way but the solenoids will be closed when the power is off.

Personally I would go with the brake booster first. It is common to all the Tauruses of your lineage.

 

[jkichline]

While you all are disussinig brakes, mine seem spongey & the sho has been drinking brake fluid, until the brake light on the dash comes on, I'll top it off with brake fluid and the light goes out only to come on a few days later and then the resoviour seems low again, is this a leak at one of the brake the lines, how urgent is the need to replace, dont want to be coming off a highway ramp and find out, oh S$*# no brakesl, input appreciated thanks,

You have a leak somewhere and it can only get worse. You better fix that as soon as possible. You will find yourself in a dangerous situation if you ignore it.

 

[Storm-Chaser]

The ABS system in the Taurus is setup using two ABS circuits (a primary and secondary circuit) to control the four brakes. The primary circuit (master cylinder aft chamber) feeds brake fluid to the ABS primary circuit, which controls the right-front and left-rear brakes. The secondary circuit (master cylinder forward chamber) feeds the ABS secondary circuit, which controls the left-front and right-rear brakes.

Your description ". . . pulled hard to the left, and the back kicked to the right...felt like the car was pivoting/rotating right over the midpoint of the car . . . ." sounds like a failure of both brakes in the primary circuit.

Remember, pulling left can be due to either a left brake braking more effectively than the others, or a right brake braking less effectively than the others. If neither rear brake was working, the car should feel like it is pivoting around the front of the vehicle as the backend attempts to come around. If the rear brakes were both working correctly, you should only get a left pull. If only the right-rear is working correctly, it may control the rate at which the backend wants to move to the right and possibly give the feel of pivoting about the center of the vehicle.


Did you use new copper crush washers?

Did you have the ABS pump bled when the brake system was opened up?


Start by pulling the ABS codes (search the forum for instructions). Next, re-bleed the brakes starting with the left-front first as a reference, then bleed all four in the proper order (RR/LF/LR/RF), noting any of the following:

• any calipers in which you find air in the fluid
  
  
• any calipers that flow better/worse than the left-front
  
  
• any calipers that produce discolored brake fluid and/or suspended particles in the fluid
  
  
• how many rounds of bleeding it takes to bleed each caliper to clear bubbles and/or particles from the caliper

Buy a large 32oz. bottle of Prestone Dot III, which was still less than $4.00 per bottle last time I checked.

Out of nowhere this problem arose...

212,000 miles on the car. All calipers are new as of ~5000 miles, as well as rotors, and rear e-brake cables.

The other day, while driving home form work I noticed my pedal went to the floor before any braking set in. Once to the floor I have to put some serious pressure on the pedal to get stopped. I'd also venture to say I'm using a very small percentage of the brakes. The car will stop, it just takes some heavy pedal effort and a little more distance to achieve the stop.

On an abandoned road I tested a panic stop from 50 mph. Found that the car pulled hard to the left, and the back kicked to the right...felt like the car was pivoting/rotating right over the midpoint of the car.

Fluid level is full in the master cylinder. I can't find anything vacuum related that has gone bad...

Seems like a master cylinder, proportion valve, or brake booster issue...but I'm just guessing here.

Any thoughts???

 

[Racer X]

So, an interesting tidbit to add to this.

Storm-Chaser is on the right path, in his assessment of a bad circuit. Here's my take on it, as I've recently corrected this issue on my car.

In the beginning, I had the soft pedal that would firm up after a pump or two. This eventually developed into a condition where if I nailed the brakes hard, the car felt like it wanted to rotate clockwise. At this point, the front right, and rear left calipers and rotors were noticibly cooler than their opposing counterparts, and I finally figured out why.

On the soft pedal firming up after a few pumps, it turned out that I had 1 slider pin out of two in the left rear that was hanging up. The other pin was fine, and it seems that pumping the brakes would bump it loose. Additionally, since the RF and LR are on the same circuit, losing pressure to caliper flex because of that hung pin, caused a loss of pressure also at the RF caliper. This served to exacerbate the pulling issues, since both calipers weren't exerting full pressure on the rotor. Eventually, all this crooked caliper action ended up seizing the pison in the bore, which ended up with no brake function at the left rear. This of course was realized in the car's continued tendancy to rotate clockwise, however with the piston now locked in place, the brake pedal firmed up substantially. In the end, replacing that caliper, and the bracket, and lubing the bejeebus out of the pins has corrected the issue, and the car now brakes straight and true, with a nice firm pedal (SS lines help to this end).

I would check for proper fluid flow at the rear caliper opposite the direction that the car pulls in under braking, and failing that, proper caliper operation (seized piston or pins).

Good luck.

 

[nistah]

RE: leak somewhere

You have a leak somewhere and it can only get worse. You better fix that as soon as possible. You will find yourself in a dangerous situation if you ignore it.

Yeah, I put the car up on the lift and saw the driver side lines right behind the dirver seat are rusted out and leaking, any suggestions where to get replacements aside from the Stealer? Thanks,