Brake Master Cylinder Difference?
Thread Starter
8th Gear
Joined: Jun 2005
Posts: 8
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From: Fort Campbell KY
Brake Master Cylinder Difference?
Anyone know the difference between the '98-04 and '05+ brake master cylinders? (18060785 and 18060779)
I'm mostly interested in bore diameter, and fitting thread size. From pictures I've found online, both look basically identical, but the '0779 is a lot less expensive.
Thanks in advance,
Dave
I'm mostly interested in bore diameter, and fitting thread size. From pictures I've found online, both look basically identical, but the '0779 is a lot less expensive.
Thanks in advance,
Dave
Last edited by Dave_Jones; Nov 5, 2006 at 03:18 PM.
Thread Starter
8th Gear
Joined: Jun 2005
Posts: 8
Likes: 0
From: Fort Campbell KY
Well, maybe someone could at least post the fitting thread diameters, for a start? That'd only take a moment with a set of calipers.
I can understand if no one really wants to disassemble their M/C, to check on the bore diameter.
I can understand if no one really wants to disassemble their M/C, to check on the bore diameter.
Thread Starter
8th Gear
Joined: Jun 2005
Posts: 8
Likes: 0
From: Fort Campbell KY
I managed to get my hands on a C6 master today. (GM P/N 18060779)
Apparently, this P/N was also used on the 05+ CTS-V.
Disassembly reveals it to be a 1" bore.
Ed, you'll probably be interested to know that internally, it's exactly the same as a '98-02 F-body M/C.
The body casting appears identical to the C5 M/C, but I was shocked to find that it's setup for inverted flare fittings, rather than the usual ISO "bubble" flare. As far as I knew, GM basically quit using inverted flares in the mid-80's; no idea why they decided to take a step backwards. Thread pitch on the fittings appears to be M12x1.0, and the reservior is identical to the C5 M/C.
At this point, I'm thinking that that the only difference between this one, and the C5 M/C, is that the C5 M/C uses ISO flare fittings. If someone can help confirm this, it would mean that they could be interchanged simply by putting the appropriate flare on the brake lines -- and a replacement C6 M/C from GM costs almost $200 less than a C5 M/C.
Apparently, this P/N was also used on the 05+ CTS-V.
Disassembly reveals it to be a 1" bore.
Ed, you'll probably be interested to know that internally, it's exactly the same as a '98-02 F-body M/C.
The body casting appears identical to the C5 M/C, but I was shocked to find that it's setup for inverted flare fittings, rather than the usual ISO "bubble" flare. As far as I knew, GM basically quit using inverted flares in the mid-80's; no idea why they decided to take a step backwards. Thread pitch on the fittings appears to be M12x1.0, and the reservior is identical to the C5 M/C.
At this point, I'm thinking that that the only difference between this one, and the C5 M/C, is that the C5 M/C uses ISO flare fittings. If someone can help confirm this, it would mean that they could be interchanged simply by putting the appropriate flare on the brake lines -- and a replacement C6 M/C from GM costs almost $200 less than a C5 M/C.
