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Dr. Hamman
Dr. Hamman, Technician
Category: Classic Car
Satisfied Customers: 2436
Experience:  I have 30 years experience repairing, restoring, and customizing cars, and pickup trucks.
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Specs: F100 1972 with donor 1973 front disc brakes and

Customer Question

Specs: F100 1972 with donor 1973 front disc brakes and original rear drums
Problem: There is no movement on the pedal and sitting on the top end. When I press on the pedal it does not move like it is stuck on the top end.
I have replaced everything on the brake system.
All Brake tubing
Rear drums, cylinder, brakes, hardware kit
Front brakes, calipers, hoses
Upgraded to a power booster from Carolina truck classics PBUFT5772 7" booster w/master, disc/drum ( I was still have the same issue with the MC only), New Proportional valve
Booster has the correct vacuum pressure to operate correctly. Build pressure and waited about a minute and half and booster held pressure so no leaks.
When I open up a line the pedal moves freely, so the MC seems ok. Released the pressure on the proportional valve.
It seems the brake system is at max pressure so the pedal does not move. I am not sure how to trouble shoot the system with this type of problem.
Submitted: 11 months ago.
Category: Classic Car
Expert:  K. Wiggins replied 11 months ago.

Hello, It sounds like the push rod that goes from the matter cylinder to the booster needs to be adjusted. This would cause the brakes to pretty much be applied even without the pedal being pressed and lead to no freeplay.

You should be able to just unbolt the mc and move it forward enough to see the rod. I'll post a link to an article below that shows the adjustment procedure. Just reply back and let me know if this does the trick. If not, we can work further.

Click here

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