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Viper · Guest

I've noticed that my entire emissions control systems have been bypassed on my 77 924 by the previous owner. While reading in the tech section, I read something that said the only reason the vacuum amplifier/resevoir exists is to run the [now defunct] EGR valve. Can I safely remove everything (temperature switch, vacuum amplifier, vacuum resevoir) and just run the brake booster and vacuum advance off the intake manifold. If so, is there an ideal sequence to connect these necessary vaccum devices up?

Also, part of my check valve was left on the manifold (haynes says its hand tightened - I had to use a 3 foot handle on my ratchet to get it to break free). Previous to my removal of it, the valve let exhaust gases into the engine bay. I was hoping to plug this up - either with a bolt or an engine plug - and was wondering if this would cause any problems.
Thanks

tyfighter123 · Joined: 19 Jan 2010 Posts: 551 Location: Colorado

old post but I have the same question about the Vacuum lines. Also Im switching over the brake Master cylinder from the 924S does the Vacuum Booster also need to be moved over or can I use the one on my 77? I have been reading in the searched articles and there is a lot of talk about the MC but not so much on the Vacuum Booster can anyone explain. Thanks
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Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)

!tom · Posted: Thu Mar 24, 2011 9:06 am Post subject:

I believe the 924S master cylinder has a stepped bore, whereas your 924 master cylinder does not. Therefore, it is not a compatible swap. In order to use your 924S master cylinder, you need to bring over the brakes as well (calipers), and also re-route the brake lines from the X configuration to the TT configuration. Otherwise your bias will be all wrong, at least, and at worst you'll have uneven braking on the left and right sides of your car.

And the vacuum booster is sized relative to the bore of your master cylinder, so you'd want to swap that over too.
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78 924 NA
5-lug

tyfighter123 · Joined: 19 Jan 2010 Posts: 551 Location: Colorado

!tom Posted: Thu Mar 24, 2011 10:06 am Post subject:

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I believe the 924S master cylinder has a stepped bore, whereas your 924 master cylinder does not. Therefore, it is not a compatible swap. In order to use your 924S master cylinder, you need to bring over the brakes as well (calipers), and also re-route the brake lines from the X configuration to the TT configuration. Otherwise your bias will be all wrong, at least, and at worst you'll have uneven braking on the left and right sides of your car.

And the vacuum booster is sized relative to the bore of your master cylinder, so you'd want to swap that over too.

Sorry I should have mentioned that I have switched over the 5 lug setup. Do you think it will make that much difference if I use the existing brake lines?
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Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

!tom · Posted: Thu Mar 24, 2011 2:49 pm Post subject:

Slam · Posted: Wed Mar 30, 2011 6:41 am Post subject:

Another thing - I believe the 1980 brake MC is a one-off year-wise. I got a rebuild kit for the Yellowjacket and it cost me around $100 (maybe more, can't recall) or so and nobody in the US stocked it. It came from Germany. Perhaps start your search for an 81 MC and skip the 80.

Just my $.02CDN.
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'88 944 Auto - may or may not resurrect