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Troubleshoot Power Brake Booster #335674 06/01/09 09:47 PM 06/01/09 09:47 PM
Joined: Sep 2004 Posts: 440 Arizona 6 69rrconvert OP mopar
69rrconvert OP mopar 6 Joined: Sep 2004 Posts: 440 Arizona	How do you troubleshoot a power brake booster? My 69 rr convert has been converted to front disc brakes using 73 A body components. Since this conversion, the brake pedal is hard and I have to stand on it to stop the car. I suspect the power booster but am unsure how to troubleshoot it. Any ideas?? Thanks in advance

Re: Troubleshoot Power Brake Booster [Re: 69rrconvert] #335675 06/01/09 09:52 PM 06/01/09 09:52 PM
Joined: Jan 2004 Posts: 9,066 Eugene, Oregon M minivan master
minivan master M Joined: Jan 2004 Posts: 9,066 Eugene, Oregon	Sounds just like my 67 when a vacuum cap came off of the booster line. Amazed at how it affected the stopping ability..

Re: Troubleshoot Power Brake Booster [Re: 69rrconvert] #335676 06/01/09 10:10 PM 06/01/09 10:10 PM
Joined: Dec 2008 Posts: 938 Poplar Bluff, Mo. 63901 2 268RTs4ME super stock
268RTs4ME super stock 2 Joined: Dec 2008 Posts: 938 Poplar Bluff, Mo. 63901	Make sure you are getting good vacum to your booster by pulling of the vacum connection at the booster. Most of the time if you have a bad booster you will hear a vacum leak inside when you press on the brake.

Re: Troubleshoot Power Brake Booster [Re: 268RTs4ME] #335677 06/01/09 10:58 PM 06/01/09 10:58 PM
Joined: Mar 2003 Posts: 15,491 the boonies aarcuda I Live Here
aarcuda I Live Here Joined: Mar 2003 Posts: 15,491 the boonies	A way to test if the booster is holding vacuum is with the engine off you can: 1) Press the brake pedal a couple times, it should become progressively harder to push, once the car is started back up with in about 30 seconds of a smooth idle the pedal should have a normal feel to it. 2) Wiggle the plastic fitting that connects the vacuum line into the booster. Be gentle so you don't break it but pushing it to the side a bit breaks the seal and you should hear a definate hiss. This hiss tells you it is holding vacuum and is good. 3) This one is kind of redundant but I had to do this to a friend to prove my point once. You can disconnect the vacuum line to the booster (and plug it off) start the engine and after the first one or two pushes of the pedal it will be hard to push. This simulates what a bad booster feels like, plugging the vacuum line back in it will return to normal pedal effort if the booster is good.

Re: Troubleshoot Power Brake Booster [Re: aarcuda] #335678 06/02/09 08:25 AM 06/02/09 08:25 AM
Joined: Sep 2004 Posts: 440 Arizona 6 69rrconvert OP mopar
69rrconvert OP mopar 6 Joined: Sep 2004 Posts: 440 Arizona	Thanks everyone for the comments. My brake pedal is hard to press even with the engine running. It sure indicates that my booster needs to be replaced.

Re: Troubleshoot Power Brake Booster [Re: 69rrconvert] #335679 06/02/09 10:24 AM 06/02/09 10:24 AM
Joined: Oct 2007 Posts: 2,808 Wisconsin wkroncke17 master
wkroncke17 master Joined: Oct 2007 Posts: 2,808 Wisconsin	Booster Dewey rebuilds them in Portland OR. http://boosterdeweyexchange.com/ There have been posts on here before that speak very highly of his services. Mine is there right now, and will post pics when I get it back.

Re: Troubleshoot Power Brake Booster [Re: wkroncke17] #335680 06/02/09 10:32 AM 06/02/09 10:32 AM
Joined: Mar 2003 Posts: 15,491 the boonies aarcuda I Live Here
aarcuda I Live Here Joined: Mar 2003 Posts: 15,491 the boonies	Quote: Booster Dewey rebuilds them in Portland OR. http://boosterdeweyexchange.com/ There have been posts on here before that speak very highly of his services. Mine is there right now, and will post pics when I get it back. he did mine and i am very very happy with the results

Re: Troubleshoot Power Brake Booster [Re: aarcuda] #335681 06/02/09 10:47 AM 06/02/09 10:47 AM
Joined: Sep 2004 Posts: 440 Arizona 6 69rrconvert OP mopar
69rrconvert OP mopar 6 Joined: Sep 2004 Posts: 440 Arizona	Thanks for the info

Re: Troubleshoot Power Brake Booster [Re: 69rrconvert] #335682 06/02/09 01:32 PM 06/02/09 01:32 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: How do you troubleshoot a power brake booster? My 69 rr convert has been converted to front disc brakes using 73 A body components. Since this conversion, the brake pedal is hard and I have to stand on it to stop the car. I suspect the power booster but am unsure how to troubleshoot it. Any ideas?? Thanks in advance Easiest check to see if the booster is working: With the engine off, put moderate pressure on the brake pedal. Then start the car. Pedal should drop about 1-2 inches. Fastest 300

Re: Troubleshoot Power Brake Booster [Re: Crizila] #335683 06/02/09 02:07 PM 06/02/09 02:07 PM
Joined: Sep 2005 Posts: 6,516 Santa Cruz, California L Lefty master
Lefty master L Joined: Sep 2005 Posts: 6,516 Santa Cruz, California	Quote: Quote: How do you troubleshoot a power brake booster? My 69 rr convert has been converted to front disc brakes using 73 A body components. Since this conversion, the brake pedal is hard and I have to stand on it to stop the car. I suspect the power booster but am unsure how to troubleshoot it. Any ideas?? Thanks in advance Easiest check to see if the booster is working: With the engine off, put moderate pressure on the brake pedal. Then start the car. Pedal should drop about 1-2 inches.

Re: Troubleshoot Power Brake Booster [Re: Crizila] #335684 06/02/09 02:42 PM 06/02/09 02:42 PM
Joined: Sep 2004 Posts: 440 Arizona 6 69rrconvert OP mopar
69rrconvert OP mopar 6 Joined: Sep 2004 Posts: 440 Arizona	Tried as you suggested and the pedal went down about an inch so maybe the booster is Ok and my problem is something else

Re: Troubleshoot Power Brake Booster [Re: 69rrconvert] #335685 06/02/09 08:37 PM 06/02/09 08:37 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	About 70% of the braking is done by the front brakes, and since your problem started when you converted over to disc, I would guess that you have a component mismatch ether in the booster ( too small - although working ) or master cyl. RU using a porportioning valve and is it adjustable? Fastest 300

Re: Troubleshoot Power Brake Booster [Re: Crizila] #335686 06/03/09 08:15 AM 06/03/09 08:15 AM
Joined: Sep 2004 Posts: 440 Arizona 6 69rrconvert OP mopar
69rrconvert OP mopar 6 Joined: Sep 2004 Posts: 440 Arizona	Not using a proportional valve. Using all stock components from the "A" body system to include the distribution valve (safety switch)

Re: Troubleshoot Power Brake Booster [Re: 69rrconvert] #335687 06/03/09 08:26 AM 06/03/09 08:26 AM
Joined: Dec 2007 Posts: 10,542 BROOK PARK, OH WILD BILL Senior Member of the Junior Dragster Club
WILD BILL Senior Member of the Junior Dragster Club Joined: Dec 2007 Posts: 10,542 BROOK PARK, OH	The best way to check the booster is with a vacuum guage. Install the gauge on one of the booster check valve ports or T it into the line. Start the engine and take a base line reading. When you step on the pedal the neddle should drop slightly and then return to the base line. If it drops and does not recover, you have a leak between the constant pressure chamber and the variable pressure chamber.

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