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Discussion Starter #1
I put my brake pedal in finally after a year and could not rmember which hole to hook it up to? Upper or lower? it is power brakes.
Thanks,
Mike
 

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lower. it should be pretty obvious, as the pushrod comes in at an angle with the power booster, and straight in on a manual setup.
 

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At least on my booster, there was no way to get the clevis installed in the top hole.

-dnult
 

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Discussion Starter #4
Great, I have it in the upper hole. Now if I can get some help with these friggen rear ebrake lines for the rear discs I should be set for a coupla days
 

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What kind of vacuum do you expect with your motor?
 

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Discussion Starter #6
I'm not sure I hope enough to run the RS equipment and the brakes how much should I have?
 

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A booster in the lower hole gives about a 3:1 pedal ratio. In order for the booster to be effective, you'll need abou 18" of vacuum.

I'm attempting to mount a booster to the top hole (6:1 pedal ratio). I'm doing this because my engine develops only 10" of vacuum. At this point, I don't know if it will work but have high hopes. I had to cut and reweld the booster bracket to line up on the top hole. With my 9" booster I should have near stock boosted performance. We'll see what happens and I'll report back in a few months.

-dnult
 

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I keep reading and hearing that a booster with discs needs 18" of vacuum to work properly. How many Camaros actually have that much vacuum after modifying the engine with bigger cams, etc? Everyone always says "I've got 15-16" of vacuum...." which isn't even close. Where's the extra vacuum coming from while driving?
I don't have an engine built yet but I'm setting the car up for power discs. I want to make SURE I'm sucking like a Hoover at speed so this drum-disc upgrade is worth the money and time. I can always install a auxillary vacuum setup but I don't want that hassle.
 

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Joe. I put together an Excel spreadsheet that calculates brake system pressures based on MS piston size, caliper piston size, and booster pressure / diameter. If you're interested I can send you a copy. 18" on a 1 1/8" MS at a 3:1 pedal ratio is basically what you need to equal a 1" manual MS at a 6:1 pedal ratio.

-dnult
 

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Originally posted by HwyStarJoe:
I keep reading and hearing that a booster with discs needs 18" of vacuum to work properly. How many Camaros actually have that much vacuum after modifying the engine with bigger cams, etc? Everyone always says "I've got 15-16" of vacuum...." which isn't even close. Where's the extra vacuum coming from while driving?
I don't have an engine built yet but I'm setting the car up for power discs. I want to make SURE I'm sucking like a Hoover at speed so this drum-disc upgrade is worth the money and time. I can always install a auxillary vacuum setup but I don't want that hassle.
You create LOTS of vacuum at steady-speed cruise and when you back off the gas. Stock Z/28's only generate 9"-10" Hg. at idle, and they all had power disc brakes. The General wouldn't have put boosters on them if they didn't have enough vacuum to operate them.
 
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