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70 Challenger disc brake problem

70pumpkin

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I think my brake booster needs to be replaced, but wanted to run it by this group. Brake booster is original I believe.

Have a 70 Challenger with factory front power discs.
  • the power brakes work only on the first press - if the brakes are pumped quickly, vacuum is lost and the brakes don't work (they become manual brakes) -- pedal gets harder and harder after each brake press - HUGE difference after 3-4 quick pumps.
    • If I wait a bit (5 secs) in between applying the brakes, vacuum builds back up and they're fine.
  • seems to be no vacuum leak from intake to check valve.
  • couldn't remove the check valve to test it. It's original and I didn't want to break it. But will try again when I have more patience.
  • The usual booster test of pumping the brake pedal, holding it, and then starting the engine passes all the time - brake pedal moves downward slightly.
Does this sound like a brake booster issue or something else?
 

Adam

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The booster needs a large vacuum port. Make sure it has not been moved, or spliced into, and the hose is not split or cracked.

The booster should hold vacuum for awhile after shut down (a few minutes at least) if it is not then you are losing vacuum.

Booster Dewey will rebuild your original for a very reasonable cost
Power Brake Booster Exchange | Providing Parts for Classic Cars
 

Steve340

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My booster went out and it was the inlet fitting. It has a rubber flap in it and it was faulty and would not allow the vacuum in to the booster.
Replaced fitting/valve all good again.
 
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