No brake pedal help

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May 16, 2024 | 07:28 PM

Jerry_85ford

Thread Starter

Mountain Pass

Joined: Feb 2020

Posts: 101

Likes: 7

No brake pedal help

Hey all, I have a 1997 f350 7.3 cclb dually and right at a year ago I did all new brakes. Rotors, calipers, pads, drums, shoes, hardware, cylinders, rubber hoses, and hard lines. Also recently did a new master cylinder so only things not new are booster, proportioning valve, and rear abs module. Last week a rear axle seal went out so I replaced it and put new shoes on, adjusted them out to have a little bit of drag and now my pedal goes completely to the floor. I didn’t open the system and there was no air previously in it as I just did the master cylinder. I’m going to recheck the shoe adjustment otherwise I’m lost. I still can drive the truck it just has very little stopping power. Maybe vacuum pump or booster? Bad master cylinder out of the box? Any help is much appreciated

May 16, 2024 | 08:28 PM

BuckHammer

Cargo Master

Joined: Jul 2010

Posts: 3,014

Likes: 115

When a similar thing happened to me, adjusting the rear brakes resolved the issue.

May 17, 2024 | 09:14 AM

paddler

More Turbo

Joined: Dec 2002

Posts: 664

Likes: 129

From: Columbia, MD

Soft brake pedal is not the booster or vacuum pump. Bad booster or pump would be no assist, and rock-hard pedal.

When in your replacements did the truck go from good brakes to pedal on the floor? Did you have good brakes AFTER replacing the master cylinder? If you didn't get a chance to check the brakes AFTER master cylinder but BEFORE rear axle seal and new shoes, I would suspect the master cylinder job... either air in lines or bad master cylinder.