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Brake booster, vacuum and pedal behavior


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Hi,

 

I think something is wrong with the brake booster or brakes on my 1.6 Na Miata. 

With the car standing still, if I press the brakes and then blip the throttle the brake pedal pushes upwards.

 

I also sometimes lockup the brakes, I think it's when I heel toe. When blipping the throttle it seems like it brakes harder.

 

Should the amount of vacuum directly control the braking effort? That seems a bit strange, wouldn't it be somekind of regulator or something?

 

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Do you have a check valve in the system?  If not, add one.

 

Also, there is a thing called a reaction disc that helps regulate the amount of brake boost by how hard you are pushing on the pedal.

 

My guess is you don't have a check valve.  The reaction disc is rarely an issue.

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2 hours ago, wvumtnbkr said:

Do you have a check valve in the system?  If not, add one.

 

Also, there is a thing called a reaction disc that helps regulate the amount of brake boost by how hard you are pushing on the pedal.

 

My guess is you don't have a check valve.  The reaction disc is rarely an issue.

 

Thanks, will check next time.

 

I think they are supposed to have one but my car has had a long life as a race car in many different series. I just got it.

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3 hours ago, Slugworks Paul said:

yeah your check valve is bad or it doesn't have one.

Imagine how it feels if your car operates on positive manifold pressure! (ask me how I know... that was scary!)

 

Hmm, positive manifold pressure? As in turbo?

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2 hours ago, turbogrill said:

 

Hmm, positive manifold pressure? As in turbo?

That's how I learned about check valves!

 

A turbo swapped rx7 into turn 4 or 5 or whatever it is called at barber (the left hander).  No brake boost.  Sweet...

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41 minutes ago, wvumtnbkr said:

That's how I learned about check valves!

 

A turbo swapped rx7 into turn 4 or 5 or whatever it is called at barber (the left hander).  No brake boost.  Sweet...

 

Trust your leg muscles?

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