• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

No Brakes when coming off of boost

jaged

Veteran CEG'er
Joined
Oct 18, 2004
Messages
974
Location
NW,Indiana
i have the 4 piston TCE wilwood kit on the front of my autox car. when i put them on (NA 3L)they worked great stopped me real quick, had a nice solid pedal. after i added the super charger ive had all kinds of problems with them. the issue is inconsistent on the street (driving not on boost), but on course it is very consistent (driving on and off boost).

the problem is that there are basically no brakes. yesterday i was on course and pushed the pedal in while coming down off of boost and it went right to the floor. went through the last 2 cones of a slalom and into the next element and barely slowed down. back in grid the pedal was ok, but not the best. visually you can see the caliper flex when the pedal is pressed.

to check things, on the way home i left foot braked while i was in boost and the brakes worked, had a solid pedal and the car lurched like it should.

ive tried running the vacuum to different ports on the UIM and have tried a couple different check valves as well

had 4-5 different people brainstorming yesterday and nothing worked. planning on draining the entire system of fluid and putting in DOT 5 this week. the fluid that is in it still looks good though
 
I know when you add forced induction to a car it can cause vacuum issues which can affect the brakes. But that shouldn't cause the pedal to go to the floor, it would just get stiff.
 
ive pulled the pads and checked to make sure the pistons move easily and they do. im going to drain the system this weekend and put fresh fluid in it.

during the event we pulled the vacuum line off of the booster and the pedal was rock hard, but still didnt brake
 
Sounds like typical brake fade, but that usually takes quite a lot of work to instigate - ESPECIALLY on a big TCE kit like yours - so that really shouldn't be happening.

I think a full fluid replacement is where I would begin as well. Then perhaps looking into a different pad compound.
 
ive pulled the pads and checked to make sure the pistons move easily and they do. im going to drain the system this weekend and put fresh fluid in it.

during the event we pulled the vacuum line off of the booster and the pedal was rock hard, but still didnt brake

Can you clarify what's happening - here you're saying that with the vacuum line removed you couldn't press the pedal hard enough to operate the brakes - which makes sense, but earlier you said the pedal went to the floor without any brake response - which would indicate a completely difference problem.
 
I too have had this problem. At first I thought it was just due to my stock brakes, but when I upgraded to a wilwood 13" setup it would still happen after being in boost. It is a little scary trying to slow down after accelerating. The car would still stop, but the pedal is very soft. I have found if I pump the brakes real quick then it seems to help, but that is obviously not a proper solution.

My Dad's car doesn't seem to have this problem, and he is just running the FSVT front rotors.

Interested to hear what you find, or others suggestions.
 
Can you clarify what's happening - here you're saying that with the vacuum line removed you couldn't press the pedal hard enough to operate the brakes - which makes sense, but earlier you said the pedal went to the floor without any brake response - which would indicate a completely difference problem.

cant say it any other way because thats exactly what happened. before we removed the vacuum line the pedal was at the floor the car slowed a bit, but not nearly what it should. i went through the last 2 cones of a slalom and through the next element with the pedal to the floor and only slowed down just enough to make the left out of the last element
 
I too have had this problem. At first I thought it was just due to my stock brakes, but when I upgraded to a wilwood 13" setup it would still happen after being in boost. It is a little scary trying to slow down after accelerating. The car would still stop, but the pedal is very soft. I have found if I pump the brakes real quick then it seems to help, but that is obviously not a proper solution.

My Dad's car doesn't seem to have this problem, and he is just running the FSVT front rotors.

Interested to hear what you find, or others suggestions.

I have not had this problem. Well the only time I have a soft brake pedal was when the axle nuts where loose and I was not aware of it.

Where is the vacuum for the wastegate/bov connected? I had it on the brake booster line first but moved it over to the vacuum line. I am running the NPG front and rear brake kit w/steel braided lines. I did change the fluid a few years ago.
 
i cant remember off the top of my head, too many black hosed in the engine bay.

from talking with my dad hes under the impression that when the wastegate opens its sucking the vacuum off for the brakes since they work while still under boost. it doesnt do it as bad when coming down from under 5lbs of boost, but when in the upper range of boost (13 lbs max) its much worse
 
wategate or bov? Maybe the supercharger is different but in my set up the wategate is openned by boost and the bov is openned by vacuum. So i am not sure how that would effect the brakes.
 
it purges when rpm drops, so if i shift slow or bump the throttle it purges. i get my terminology messed up sometimes
 
I'm thinking you should have a one-way check valve on the brake booster line to prevent vacuum loss from the blow-off/bypass/diverter valve.
 
Then if you're positive that the check valve is working, I would suspect you might have a leak at the booster.
 
Back
Top