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66-96 Ford Broncos - Early & Full Size
Richard Creager

Replaced rear wheel cylinders,shoes,axle seals,bearings on a 1987 Bron

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I replaced the rear wheel cylinders and shoes on my 87 Bronco II. I had leaking axle seals so I replaced the seals, bearings and axles. After bleeding all 4 wheels and adjusting out the rear shoes I gave it a test drive. I have a good hard pedal but when I apply the brakes for a hard stop the car comes to a slow stop. During the hard stop the pedal feels hard and does not bottom out but the brakes just coast to a stop when they should stop aggressively. Also, I replaced the vacuum booster trying to fix the problem and it didn't help. I was wondering what the small vacuum valve is on the brake pedal. It seams to close when the pedal is released and when the pedal is pressed down you can hear a hiss at the valve. It popped out when I was installing the new booster so I was wondering how to adjust it. What do I need to do to get the brakes to work correctly?  Richard

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Hi Richard.., welcome..! 

Sounds like you have mech. experience & got everything right.

The only thing I can think of would be the ABS system if, in fact, your rig has that.

--- What were the brakes doing prior to your work..?

 

That "valve" on the pedal is a mystery. Any hissing would indicate a vacuum leak to me. 

 

Be interesting to see what some of the other members have to say about this.... :-B

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Hey Richard, Welcome.

 

The "valve on the pedal could be for cruise control canceling.

Be sure you have the primary and secondary rear shoes on correct and they are adjusted properly.

Good Luck

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The valve is definitely for cruise control cancelling.  I am going to suggest that the brakes are not properly bled.  Air in the lines will cause a hard pedal that is infective. The procedure is to bleed the furthest brake from the reservoir and work to the closest. ie. right rear, left rear, right front, left front.  If doing it by yourself, get a break bleeding kit from a parts store and suck the fluid, that way you can visually see when all air is out of the line. also it will not let air back into the line while closing the valve.  Just be sure to keep the reservoir filled while doing this.  Get a quart of fluid and check the reservoir as you are bleeding the any particular line.  You can do that while bleeding since a bleed kit will not let air back in the line while you are replacing fluid in the reservoir.

 

Hope that makes sense to you, it probably isn't that clear 0:) .

 

Good luck,

 

:)>-

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Thanks everybody for your replies. I did figure out that the vacuum switch was for the cruise control.  How do you tell the difference between the primary
 and secondary shoes? The shoes I purchased all looked exactly the same. I replaced the master cylinder and bed the whole system again but it stll feels the same in a hard stop. I'm wondering if the ABS system hasn't been working all these years and now is. Just making the brakes feel differently.

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When making an emergency hard breaking stop, you should feel the brakes pulsate as the ABS detects wheels locking up.

 

:)>-

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The primary shoe has a little less friction lining and should be installed on the side toward the front of the vehicle.  This allows the shoes to transfer motion during a forward stop to inertia and apply more pressure on to the drum increasing the stopping force.  If the shoes are reversed the "inertial assist" is lost and the stopping force is simply from hydraulic force.

Good Luck

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