Who is really using a C5 Corvette Master Cylinder?

[brn agn]

I've been trying to get a C5 Corvette Master Cylinder to work in my Nova. The difficulty I am having is locating a M12-1.5 tube nut (for the front port) that will work with 3/16" brake tubing. I've called mutliple shops and have visited several parts stores with no luck. How is everyone else making this work?

[EFI69Cam]

The c5 has 2 6mm lines. The nearly identical 4th gen master has one of each.

Why not use the 4th gen?

[brn agn]

I like the fact that the lines exit on the left hand side of the master and I already had the master cylinder.

[Apogee]

I've been trying to get a C5 Corvette Master Cylinder to work in my Nova. The difficulty I am having is locating a M12-1.5 tube nut (for the front port) that will work with 3/16" brake tubing. I've called mutliple shops and have visited several parts stores with no luck. How is everyone else making this work?

I could be mistaken, but my notes show the C5 MC to have the same port sizes as the 98-02 F-body MC which are M12x1.0 (front port) and M11x1.5 (rear port) female bubble flares, just on the opposite side. That might help in your search as those are a more standard size.

Here's a link to a company with pretty much every "standard" tube nut known to exist...at least to me. http://www.fmsiinc.com/brake-line-fittings.htm

Tobin
KORE3

[brn agn]

The REAR port is definitely a M12-1.0. The front port however appears to be an M12-1.5. I have measured the original tube nut (it is for 1/4" tubing) and the major OD is 11.80 mm, which is the same as the M12-1.0. One last thing I will do is find an M12-1.50 machine nut and see if it threads on the tube nut.

[Apogee]

The REAR port is definitely a M12-1.0. The front port however appears to be an M12-1.5. I have measured the original tube nut (it is for 1/4" tubing) and the major OD is 11.80 mm, which is the same as the M12-1.0. One last thing I will do is find an M12-1.50 machine nut and see if it threads on the tube nut.

Using calipers, measure the minor diameter (ID) of the MC ports and you should be able to determine the threads without a thread gauge or proper tube nut for reference. If it is M12x1.5, the ID should be a nominal 10.5mm [.413"]. If it's M12x1.0, it'll be 11mm [.433"]. Usually you can tell if it's coarse or fine thread visually, but if not, measuring should remove all doubt. An M11x1.5 port will have a 9.5mm [.374"] ID...pretty straight forward if you've got some decent calipers.

Tobin
KORE3

[brn agn]

Thanks for the info. I measured the ports. The front port (fine thread) has a minor ID of 10.9mm and the rear port (coarse thread) has a minor ID of 10.4mm.

The good news is that I found a place that sells 3/16" tube nuts for both ports. I purchased the tube nuts and they are indeed M12-1.0 for the front port and M12-1.5 for the rear port (I confirmed that they fit correctly).

Brakequip is the name of the company that makes the correct tube nuts. I actually bought a few extra sets, so if anyone else is installing a C5 master cylinder and is using 3/16" lines, let me know.

[Apogee]

Good info. Thanks for the correction.

Tobin
KORE3