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| Registered Join Date: Sep 2008 Location: Ghent, Belgium 
					Posts: 282
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				Possible to replace brake booster with master cylinder in place?
			 
			Long story short, the brake booster on my fathers' SC doesn't work.  I found a replacement, but wanted to know if it's possible to replace it while leaving the master cylinder in place, so I don't have to bleed the brakes. | ||
|  05-28-2017, 12:32 AM | 
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| Registered User | 
			I asked this question a few years back and didn't get a definitive answer - the sense seemed to be that it would probably work.   Before you go to the trouble, check to see if the problem is in fact with the booster - it's a pretty robust part and rarely fails. I thought mine was cooked, but it turns out the vacuum line was damaged. Disconnect the line where it enters the trunk and check to see if you're drawing vacuum. | ||
|  05-28-2017, 05:12 AM | 
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| Registered Join Date: Sep 2008 Location: Ghent, Belgium 
					Posts: 282
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			Yes I tried that and I have vacuum there...  At first I thought it was because of the bremtek brakes, but since I've fitted standard SC brakes there's still no change. | ||
|  05-28-2017, 06:10 AM | 
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| Registered Join Date: Jul 2012 Location: GA 
					Posts: 919
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			Also check the brake pedal itself. Mine was binding and I wasn't getting the full travel. Very hard pedal. I was pretty convinced it was the booster but it wasn't.
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|  05-28-2017, 05:45 PM | 
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| Registered | 
			Nope  Ernie | ||
|  05-28-2017, 06:37 PM | 
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| ROW '78 911 Targa | 
			How old are the rubber brake lines?
		 
				__________________ Dennis Euro 1978 SC Targa, SSI's, Dansk 2/1, PMO ITBs, Electric A/C Need a New Wiring Harness? PM or e-mail me. Search for "harnesses" in the classifieds. | ||
|  05-28-2017, 08:11 PM | 
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| Registered Join Date: Sep 2008 Location: Ghent, Belgium 
					Posts: 282
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			Brake lines are new, calipers are new, brake fluid is fresh. I'll try and see where I end    | ||
|  05-28-2017, 09:58 PM | 
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| Registered Join Date: Jun 2004 Location: Oxford, Ct. 
					Posts: 2,297
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			You can swap the booster and master as a unit You will have to bleed the brakes
		 
				__________________ 07 GT3 Cup S 4.0, 00 986, 78 911 old school gt car 77 BMW R100S 99 Ducati 996S 04 BMW R1150R DanielJacobsLLC.com | ||
|  05-29-2017, 06:49 AM | 
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| Registered Join Date: Sep 2008 Location: Ghent, Belgium 
					Posts: 282
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			Quick update: -Turns out I had a vacuum leak at the hard line that comes out of the transmission tunnel, there was a chunk of metal missing, go figure... So before you change out your booster, check for vacuum leaks where you least expect them  -BUT: I learned it IS possible to replace the brake booster without having to bleed the brakes. | ||
|  12-29-2017, 12:05 PM | 
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| Registered Join Date: Oct 2006 Location: MYR S.C. 
					Posts: 17,321
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			that's what I was going to suggest. pull a vacuum on the booster and see if it holds. if it does, connect it back up, then pull a vacuum on the line back at the engine bay, this is a good check to do anyway as you can have a vacuum leak, the booster still works but it will effect the engine. 
				__________________ 86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD 88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_  _] RUNNING: [__] NOT RUNNING: 01 suburban 330K:: [_  _] RUNNING: [__] NOT RUNNING: RACE CAR:: sold | ||
|  01-03-2018, 08:13 AM | 
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