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67 Camaro break question.


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Hey can anybody tell me the difference:  I want to put a booster for my break's master cylinder. I found 3 types that can fit my car. One is a 11 1/2" dia. booster for a 1" bore M.C. one is a 9" dia. booster and another is a 7" dual diafram booster. They are all compatible but which one does what?

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1 hour ago, TerryB said:

It's brake not break

Unless his brakes are broken.

Why won't you tell us exactly what you're trying to do??? Is this a stock restoration or are you attempting to upgrade? As I stated in the original post, to which you still haven't responded, you can get all of the correct, OEM style parts from a number of vendors. If you are deviating from stock, then it is a crap shoot as far as getting something that will work well

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Hmnn, can't catch a break on your first question. I'm sure you'll be eager to ask another, lol!

 

So, different boosters are for different applications, I suspect you currently have a 4 wheel drum manual set-up. If that's the case, you will probably be looking at an 11 inch (actually slightly less) booster. They are based on vehicle options. Some options are 4 wheel drum, front disc rear drum, 4 wheel disc, and even engine size. The smaller boosters are generally big block applications, with front disc, or all drums.

 

Pick the booster that most closely matches your current set-up, with which you merely want to add the power option. Keep in mind you may have to experiment on the rod length.

  

Hope this helps a little.

 

Jim

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Power BRAKES were a factory available option on this car.  Get a factory replacement booster. 

 

Understand that a vacuum brake booster uses atmospheric pressure on a rubber DIAPHRAGM to create the power assist.  Since air pressure is pretty much constant at 14.7 PSI, changes in diaphragm diameter (and thus area) will change the amount of boost available from a given booster.

 

A 9" booster has only 2/3 the diaphragm area of an 11" booster and thus only provides 2/3 as much power assist.  A dual diaphragm 9" booster, however, has 33% MORE area than an 11" booster, and correspondingly more boost.  It's larger size may present a fitment problem, however.  The stock booster was an 11" single diaphragm unit.

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22 hours ago, joe_padavano said:

Power BRAKES were a factory available option on this car.  Get a factory replacement booster. 

 

Understand that a vacuum brake booster uses atmospheric pressure on a rubber DIAPHRAGM to create the power assist.  Since air pressure is pretty much constant at 14.7 PSI, changes in diaphragm diameter (and thus area) will change the amount of boost available from a given booster.

 

A 9" booster has only 2/3 the diaphragm area of an 11" booster and thus only provides 2/3 as much power assist.  A dual diaphragm 9" booster, however, has 33% MORE area than an 11" booster, and correspondingly more boost.  It's larger size may present a fitment problem, however.  The stock booster was an 11" single diaphragm unit.

Thanks Joe! this was very informative . I'll go with the 11". It seems to be the best match with the Delco model.

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On 12/17/2016 at 10:57 AM, MyJetstar1 said:

Hmnn, can't catch a break on your first question. I'm sure you'll be eager to ask another, lol!

 

So, different boosters are for different applications, I suspect you currently have a 4 wheel drum manual set-up. If that's the case, you will probably be looking at an 11 inch (actually slightly less) booster. They are based on vehicle options. Some options are 4 wheel drum, front disc rear drum, 4 wheel disc, and even engine size. The smaller boosters are generally big block applications, with front disc, or all drums.

 

Pick the booster that most closely matches your current set-up, with which you merely want to add the power option. Keep in mind you may have to experiment on the rod length.

  

Hope this helps a little.

 

Jim

Thanks Jim, Both you and Joe gave me good info. I appreciate it.

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On 12/17/2016 at 10:57 AM, MyJetstar1 said:

The smaller boosters are generally big block applications, with front disc, or all drums.

 

Not really.  The booster diameter was the same for both SBC and BBC in this application. As I noted above, if you do the math, you find that a smaller single diaphragm booster provides LESS assist than a larger one, so you DON'T want a smaller booster for a heavier BBC application.  Similarly, since disk brake are not self-energizing, you DON'T want a smaller booster for that application, either.  A dual diaphragm booster can provide more assist while increasing valve cover clearance, but Chevy didn't seen to need this for factory installations.  Again, why reinvent this?  You can buy factory replacement boosters everywhere.

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On ‎12‎/‎17‎/‎2016 at 10:57 AM, MyJetstar1 said:

Keep in mind you may have to experiment on the rod length.

^ this is very important on installation of a booster, when bolting the master cylinder to it.   This part may need adjusting if the booster arrives without a master cylinder, and you have to get a master cylinder elsewhere.

 

If the adjustable rod between the booster and master cylinder is adjusted "too long", then it won't let the inside piston of the master cylinder to fully retract.  If it does not retract enough when the brake pedal is released, two things could happen: 

 

  One would be that the brakes are still slightly engaged, which could cause the brakes to overheat/swell up,  and stay locked up when the car is brought to a full stop( if hot enough..)

 

2nd thing that might happen, is that it will be very difficult to bleed the brakes when you are finished installing everything.

 

.

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