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The Brake Booster has an adjustable Pushrod which pushes on the Master Cylinder Piston. If the Pushrod is adjusted too long, it will prevent the Master Cylinder Piston from completely releasing hydraulic pressure causing the brakes to drag. If the Pushrod is adjusted too short, it will cause excessive brake pedal travel and may cause a "clunk" when it surges forward.

A new Brake Booster is said to be adjusted at the factory and ready for install. Yet, I installed a new A-1 Cardone Brake Booster and found the Pushrod was significantly short causing mushy brakes, a low pedal and an occasional clunk.

I know there are other methods using a specific .980-.995" adjustment gauge, but this is what worked for me.

Start by unbolting the Master Cylinder from the Brake Booster. Pull the Master Cylinder forward off of the mounting bolts exposing the adjustable Brake Booster Pushrod. Be careful not to bend or damage the hydraulic lines attached to the Master Cylinder.

Lengthen the Brake Booster Pushrod by holding the shaft with pliers and screwing the adjustable tip outward a little at a time until the Master Cylinder will no longer mount flush against the Brake Booster.

Then adjust the tip inward just enough that the Master Cylinder will just slide up flush to the Brake Booster mounting surface without pushing on the Pushrod. This may take several small adjustments and will become your "point of no play".

Screw the tip of the Pushrod inward an additional 1/16" and bolt the Master Cylinder back onto the Brake Booster. Test the the brakes and your done. :thumbup


 

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That’s good to know. Quick question, my bronco has a ton of play, and you can hear air rushing when you press the brake, but the brake light switch isn’t activated yet. After adjusting this, can it fix this problem? (Because there will be less play?)
 

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1986 Bronco, 351w, Edelbrock aluminum top end, Holley 600, 4" BDS lift, 35" Maxxis Razr's, stuff..
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And that adjustment is super sensitive - the sweet spot is very small. If you hear air when you pedal you've got a leaking diaphragm in the booster.
 
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