vacuum booster test
Thread Starter
Pro
Joined: Sep 2002
Posts: 620
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From: San Antonio TX
vacuum booster test
I've searched the archives and think I've found the answer but...I'm still not sure.
If I attach a manual vacuum pump to the brake vacuum booster, I should be able to pump it down to some level of vacuum, and it should hold for a reasonable amount of time.
Am I correct?
Thanks, I really do miss being able to absolutely count on my brakes!
If I attach a manual vacuum pump to the brake vacuum booster, I should be able to pump it down to some level of vacuum, and it should hold for a reasonable amount of time.
Am I correct?
Thanks, I really do miss being able to absolutely count on my brakes!
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Originally Posted by cchristo
I've searched the archives and think I've found the answer but...I'm still not sure.
If I attach a manual vacuum pump to the brake vacuum booster, I should be able to pump it down to some level of vacuum, and it should hold for a reasonable amount of time.
Am I correct?
Thanks, I really do miss being able to absolutely count on my brakes!
If I attach a manual vacuum pump to the brake vacuum booster, I should be able to pump it down to some level of vacuum, and it should hold for a reasonable amount of time.
Am I correct?
Thanks, I really do miss being able to absolutely count on my brakes!
Thread Starter
Pro
Joined: Sep 2002
Posts: 620
Likes: 2
From: San Antonio TX
opening the vacuum booster.
Moving on to where I think this will probably lead me.......
Has anyone here successfully opened up a booster and repaired it?
It looks as though it would be fairly straighforward. It appears as though the two halves are twisted together in a cam type fashion. If I can figure out how to get a grip on the two halves, can I just open 'er up?
From there, I figure I'll find some sort of sheet of rubber, and it will probably either have a pinhole in it that can be easily patched, or I'll find it all dry rotted and deteriorated. Hmmm.
Has anyone here successfully opened up a booster and repaired it?
It looks as though it would be fairly straighforward. It appears as though the two halves are twisted together in a cam type fashion. If I can figure out how to get a grip on the two halves, can I just open 'er up?
From there, I figure I'll find some sort of sheet of rubber, and it will probably either have a pinhole in it that can be easily patched, or I'll find it all dry rotted and deteriorated. Hmmm.
Thread Starter
Pro
Joined: Sep 2002
Posts: 620
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From: San Antonio TX
Originally Posted by big_G
Yes, but depending on what tool/device you are using to pull the vacuum, it may take a while. Also, verify proper function of the check valve.
Check valve is good, but I bypassed it for my test anyway. I'm just using a little hand operated "mighty vac".
Probably not the greatest, but I feel I should still be able to create a vacuum.
Tech Contributor
Joined: Aug 1999
Posts: 14,375
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From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by cchristo
Has anyone here successfully opened up a booster and repaired it?
It looks as though it would be fairly straighforward. It appears as though the two halves are twisted together in a cam type fashion. If I can figure out how to get a grip on the two halves, can I just open 'er up?
From there, I figure I'll find some sort of sheet of rubber, and it will probably either have a pinhole in it that can be easily patched, or I'll find it all dry rotted and deteriorated. Hmmm.
It looks as though it would be fairly straighforward. It appears as though the two halves are twisted together in a cam type fashion. If I can figure out how to get a grip on the two halves, can I just open 'er up?
From there, I figure I'll find some sort of sheet of rubber, and it will probably either have a pinhole in it that can be easily patched, or I'll find it all dry rotted and deteriorated. Hmmm.
Thread Starter
Pro
Joined: Sep 2002
Posts: 620
Likes: 2
From: San Antonio TX
Originally Posted by lars
I've pulled them apart several times to chrome plate and cad plate the front & rear "shells" for show cars. The two halves are pretty tight: You need a good heavy duty machinist's vice and a freakin' big hammer (my favorite tool). But to repair it, you have to have access to repair parts - not stocked items at NAPA or Corvette Central. Why don't you just take it over to you local power brake rebuild place and have them fix it for the $75 they normally charge to do a complete rebuild on the thing?
If I can fix something myself, even if it's not as quick or cheap as letting someone else do it, I get more satisfaction out of it. Still, I might let someone else do this one.
Thanks for all the help everyone! You all have answered my questions.
Melting Slicks
Joined: Feb 2003
Posts: 2,529
Likes: 27
From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
I have the same issue on my booster. I can hear it leaking air when I shut the car off!!!
Just my $0.02 worth
Autozone...Advance have (and I am sure other parts house have them) reman'd unit from Cardone for $79. There are some suppliers on Ebay with new units for about the same $$. They also have them loaded(w/rebuilt master cylinder) for $99....seems like a deal..
I am not a big fan of reman'd stuff. I think the boster would be ok. But I will most likely get a NEW master cylinder instead of a reman.
Mark
Just my $0.02 worth
Autozone...Advance have (and I am sure other parts house have them) reman'd unit from Cardone for $79. There are some suppliers on Ebay with new units for about the same $$. They also have them loaded(w/rebuilt master cylinder) for $99....seems like a deal..
I am not a big fan of reman'd stuff. I think the boster would be ok. But I will most likely get a NEW master cylinder instead of a reman.
Mark
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Race Director
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From: San Diego - Deep Within The State of CONFUSION!
The way to test the booster is not by sucking it with a pump. you step firmly on the brake pedal, then start the engine. The brake pedal should then fall softly about an inch or so as the booster voids of air.
If the pedal stays hard after the engine starts, (and it is getting vacuum), then the booster is bad.
If the pedal stays hard after the engine starts, (and it is getting vacuum), then the booster is bad.
That's exactly right. Darned good comment, Paul. 
Melting Slicks
Joined: Nov 2003
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From: St. Charles Mo
CI 5 & 8 Veteran
Originally Posted by SanDiegoPaul
The way to test the booster is not by sucking it with a pump. you step firmly on the brake pedal, then start the engine. The brake pedal should then fall softly about an inch or so as the booster voids of air.
If the pedal stays hard after the engine starts, (and it is getting vacuum), then the booster is bad.
If the pedal stays hard after the engine starts, (and it is getting vacuum), then the booster is bad.
P.S. I was considering a vacuum leak test on the booster before I launch off and do the replacement just to verify. Does this sound logical?
Bullshark
Last edited by Bullshark; Feb 24, 2006 at 12:42 PM.
Race Director
Joined: Sep 2002
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From: San Diego - Deep Within The State of CONFUSION!
Originally Posted by Bullshark
P.S. I was considering a vacuum leak test on the booster before I launch off and do the replacement just to verify. Does this sound logical?
Bullshark
1
is the check-valve in place and good? Make sure air only goes ONE WAY thru the valve.2
If the check valve is good, then run the engine for a minute to build vacuum in the booster. Do NOT touch the brake pedal. Then pull the check-valve and see how much vacuum is in there after a minute or two.
Melting Slicks
Joined: Feb 2003
Posts: 2,529
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From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
Originally Posted by SanDiegoPaul
If that's the case then
1 is the check-valve in place and good? Make sure air only goes ONE WAY thru the valve.
2 If the check valve is good, then run the engine for a minute to build vacuum in the booster. Do NOT touch the brake pedal. Then pull the check-valve and see how much vacuum is in there after a minute or two.
1
is the check-valve in place and good? Make sure air only goes ONE WAY thru the valve.2
If the check valve is good, then run the engine for a minute to build vacuum in the booster. Do NOT touch the brake pedal. Then pull the check-valve and see how much vacuum is in there after a minute or two.thanks Paul
Le Mans Master
Joined: Jul 2005
Posts: 5,752
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From: Austin Texas
Originally Posted by Bullshark
Paul, can there be a small vacuum leak in the booster that could fool you when conducting that test??? I have a situation where I seem to get intermitent performance, i.e. somtimes I have brakes, yet other times I seem to have to really step on the pedal. When I step on the brakes at idle, I hear a hiss in the area of the booster which sounds like escaping air. The standard test you refer to seems to pass muster???? I replaced the master cylinder and calipers and have convinced myself those are not the problem. Next on the list is booster replacement.
P.S. I was considering a vacuum leak test on the booster before I launch off and do the replacement just to verify. Does this sound logical?
Bullshark
P.S. I was considering a vacuum leak test on the booster before I launch off and do the replacement just to verify. Does this sound logical?
Bullshark
Melting Slicks
Joined: Nov 2003
Posts: 2,668
Likes: 119
From: St. Charles Mo
CI 5 & 8 Veteran
Originally Posted by SanDiegoPaul
If that's the case then
1 is the check-valve in place and good? Make sure air only goes ONE WAY thru the valve.
2 If the check valve is good, then run the engine for a minute to build vacuum in the booster. Do NOT touch the brake pedal. Then pull the check-valve and see how much vacuum is in there after a minute or two.
1
is the check-valve in place and good? Make sure air only goes ONE WAY thru the valve.2
If the check valve is good, then run the engine for a minute to build vacuum in the booster. Do NOT touch the brake pedal. Then pull the check-valve and see how much vacuum is in there after a minute or two. The booster vac comes straight from the manifold, so if it ( the booster) has a small leak, only the brakes get affected....right?
Bullshark
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
Having just converted from my olde tyme vacuum booster to the hydroboost unit, and having for the very FIRST TIME in TEN years, the ability for this shark to actually stand on it's NOSE....an acrobatic shark......
lemme say this...upon tearing my vacuum booster apart I found there was NO noticeable defect.....diaphrams, seals, plates, everthing seemed fine, and too boot it acted normal...just stucked as far as applying BRAKES,.....
give up allready do a hydroboost conversion....
GENE
lemme say this...upon tearing my vacuum booster apart I found there was NO noticeable defect.....diaphrams, seals, plates, everthing seemed fine, and too boot it acted normal...just stucked as far as applying BRAKES,.....
give up allready do a hydroboost conversion....
GENE
