I am a total newbie here, so go easy on me fellas...I have a 93 SHO that I've had for 2 years. The brakes were going soft, so I had a friend install a new master cylinder. The brakes were bled and it still was soft. A mechanic friend of mine said to bleed them a few more times, so we did. Three days later, the brakes are going soft. The friend who installed the mc thinks its the power brake booster. My mechanic friend thinks either the proportioning valve has some dirt in it, or I need to get another master cylinder. Any thoughts? I am trying to save a trip to the Ford dealer shop.
Soft brakes
- Thread starter Bearcat
- Start date
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SHOracer14
Me-0 Diffs-6
I would try bleeding the brakes while the vehicle is on the ground and the vehicle is running. I ran into a similar issue one time on my 93' after a master cylinder replacement. Sometimes air may get into the ABS pump/motor and you can usually work it out if you bleed while the vehicle is running. If that does not work double check for leakage anywhere (including at the bleeders). IF there are no other leaks I would suspect a bad master cylinder. Normally when a booster goes bad it will be harder to push the pedal. Also, if you do have to remove the master again be sure to check for any brake fluid that may have gotten into the booster (if the old master cylinder had a blown rear seal).
frosho
WOLFMAN
Also, before you try to bleed them again, take the car out somewhere where there is limited traction, and stomp on the brakes hard enough to trigger the ABS. It'll help to work air out of the ABS module, if there is any in there.
Shoaz
Studly dood
As has been mentioned, either get the ABS to cycle a few times somewhere or get/borrow one of the Thexton valve controller thingies to bleed through the ABS. That assures that fluid in the lines AND in the ABS get bled.
Another possible culprit is old rubber brake lines that have gone soft. When they get old they expand more and it makes for a mushy pedal.
Another possible culprit is old rubber brake lines that have gone soft. When they get old they expand more and it makes for a mushy pedal.
Thanks for the tip. I did the slam on the brakes on ice to engage the ABS and it seemed to help. The brakes work on the first three taps and on the fourth they start get soft...then it goes back to working fine, three taps, etc. I'll try bleeding the brakes one more time.
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boat
Likes blue ones
Once you get everything checked and verified, and you have the cash to do so, replace your rubber brake lines with some stainless brake lines from shosource, it will help to further remove the soft brake pedal, that SHOAZ is referring to.
Thanks, I'll do that!
kevinspann
Don't take my advice.
FWIW the pedal in my car was reasonably stiff with rubber lines too.
Phoenix
SHOHOLIC
And by all means , dont waste your money by bringing it to your dealer , they dont have a clue about these old shos.
We should point you in the right direction.
We should point you in the right direction.
Or replace them with new rubber lines, which are inexpensive. If they are original, they need to be replaced. BTW, the SHO has to be bled with the rear wheels on the ground because of the load proportioning valve that is attached to the rear suspension arm. It also helps if the rear of the car is higher than the front.
LJRuddy
Pop lock n drop
So your brakes go soft when applying constant pressure to the pedal? Park on a hill and apply constant pressure to the pedal. Does the car begin to roll after a few seconds of holding the brake pedal at an exact position? If so, your master cylinder is letting fluid flow past the seals which is giving you this symptom.
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