Brakes

[JakeJeffery]

Please help. I have a 1973 Bronco that I have replaced with a master cylinder, brake lines, converted front brakes to disc brakes, new drums in the rear, new power brake booster and proportioning valve and I simply cannot make the brakes work. (Can you tell me what the vacuum number should be?) Do I not have enough vacuum for the booster to work properly? Should I install a vacuum booster pump? Would that help. Please let me know your thoughts.

 

[serial car restorer]

More info, please. What is not right? No brakes at all? Poor stopping? Soft pedal?

 

[JakeJeffery]

More info, please. What is not right? No brakes at all? Poor stopping? Soft pedal?

Very poor stopping, Hard pedal.

 

[bronco italiano]

What is your current vacuum reading at the manifold to booster?
If you cam has too much duration that can be a problem.
Did you check your booster to make sure it is not leaking? Just because it is "New" (these days) doesn't mean it works properly.

 

[JakeJeffery]

What is your current vacuum reading at the manifold to booster?
If you cam has too much duration that can be a problem.
Did you check your booster to make sure it is not leaking? Just because it is "New" (these days) doesn't mean it works properly.

I would need to read that vacuum, I don't have it. I do know the duration is in the high 200. Yes no leaks. Fells like air in the lines but I know there is no air.

 

[JakeJeffery]

I would need to read that vacuum, I don't have it. I do know the duration is in the high 200. Yes no leaks. Fells like air in the lines but I know there is no air.

In fact here are my cam spec. int. lift 458, Exh. lift 483, Duration @ .50: 218-130 Advertised Duration 293-307

 

[serial car restorer]

Fells like air in the lines but I know there is no air.

Hard pedal and air in the lines don't match. Air in the lines will give a soft, mushy pedal. Definitely wouldn't be hard. Sounds like a bad booster or insufficient vacuum to me.

 

[Master Chief]

Photos are a great help to us. Are your vacuum lines correct?

 

[serial car restorer]

Are your vacuum lines correct?

That's a good thought. Where are you pulling vacuum from? A manifold port?