Brake Effort OK? Need Advice

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redneckmba

redneckmba

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I'm a newer owner of a 1974 Valiant with 318 and factory power disc brakes. The power brakes require a lot more effort than I am used to. There is definately power assist - but pedal effort seems high compared to newer cars. Is this normal??

The previous owner had replaced the front pads and calipers. Also he replaced the rubber hoses all round.

I checked the idle vacuum right at the booster and got a steady 18"

The brake/front end shop I do business with does a fair number of classic cars. The technician noted that the amount of effort may be normal; newer cars are more "refined" and may need less effort. The technician was not convinced there was a problem. But he wasn't sure there wasn't a problem either. Separately, he found the rear drums were warpped and he replaced them.

Those of you with factory power disc brakes of the same vintage: Is is normal for your Mopar to have a higher pedal effort compared with more modern power disc brake cars that you have driven?
 
I have a 73 Dart Sport and my pedal feels no different than my 2004 Buick Lesabre. I wonder if there is perforations in the diaphragm in your brake booster? Not a huge leak, but enough to give you a harder pedal.
 
Try this:
start engine and let it run for a minute or two (keep your foot off the brake until the end)
shut off engine
wait about 15 minutes
now step on the brake pedal, if you hear a "whoosh" sound and the brake pedal effort feels normal the the booster is fine. If the pedal is hard as a rock then the booster is bad or the check valve isn't holding.

Yes newer cars have a very light feeling brake pedal compared to an old car, so it might just be that your not used to how the brakes should feel.
 
OK. Thanks for the feed back. I will do the leak-down test tonight. The booster looks really old as it has some rust on it. Could be the original booster and it is getting old (like me).
 
Could some of the resistance be in the pedal and linkage parts before the booster ?
Those are the most neglcted parts of a brake system.
 
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