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Join Date: Apr 2004
Location: N/A
Posts: 351
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how to test brake booster vacuum?
I rebuilt my brakes last year. Caliper rebuild, new pads, new mc and new flexible lines. To date, I can't bring the car to a hard stop (ie get the brakes to lock up) despite about 500 miles on the pads. I've bled the brakes 7 times with a power bleeder, a vacuum bleeder and with the wifey bleeder. After a search on the topic, I also just ensured that the o ring is installed between the mc and booster.
The final thing I'm thinking is maybe there no vacuum at the booster. How do I check that...with a gauge? Thanks, Graham
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"Penelope" 1980 SC Targa in Grand Prix White |
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04-14-2005, 04:54 PM
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Location: Daytona, Florida, USA
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Put your foot on the pedal, push, start the car. You should feel a change in the pedal
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04-14-2005, 05:15 PM
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bump
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"Penelope" 1980 SC Targa in Grand Prix White |
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04-14-2005, 08:24 PM
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Location: Long Island, N.Y.
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YEAH, WHAT WATER 911 SAID, HE'S RIGHT ON.
j.p. |
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04-14-2005, 08:40 PM
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If you are comparing it to how all the 2005 cars stop with their factory brakes then you will never be happy with a 1980 stock brake system.
More info is needed: - What did you have done to the rotors? - What does the pedal feel like? Hard? Soft? Mushy? - Do you feel an up and down action in the brake pedal? - Does it stop straight but slow? - What type brake pads did you install? Factory new? Rebuilt? Bonded or riveted? Metallic, semi-metallic or non-metallic? If the car stops straight with a solid pedel, I would look at the quality of brake pad.
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Terry Hastings Baltimore, MD 1972 911T LTHSURVEY@AOL.com |
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04-15-2005, 03:35 AM
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Location: Massachusetts
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I just tried the "Put your foot on the pedal, push, start the car. You should feel a change in the pedal" method on my '86 911 (stock). I pressed and held the brake pedal and felt absolutely no difference in the pedal before, during and after starting the engine. Can someone else with an ''86 try this and let me know what you feel.
Now I would like to check for vacuum. On other cars when I wanted to check the vacuum at the boost, I pull the vacuum line off the boost which results in a significant change in idle speed and smoothness. Will the same be true on the 3.2 911? Any other thoughts on troubleshooting the boost? Thanks.
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CWL '86 Carrera Coupe '88 Carrera Cab '02 525i Sedan |
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11-17-2007, 02:02 PM
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Join Date: May 2002
Location: Massachusetts
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Can someone with a '86 (or similar mid '80s Carerra) try the "press the brake, start the engine, feel the pedal change" method on the way to work? My brake pedal has no noticable change when the engine is started.
Thanks, C
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CWL '86 Carrera Coupe '88 Carrera Cab '02 525i Sedan |
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11-19-2007, 03:44 AM
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