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Disc brake conversion, which m/c?


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I want to do the rear disc swap on a 76 280, do I need to chang the master cylinder? If so, which one should I use and will it mount to the stock vacuum assembly? Can I use a 280ZX or 300z m/c with stock brakes and do the rear set-up later?

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You can use the 15/16 master cylinder from a 280ZX or you can use the stock master cylinder, as either one will bolt up to the stock master vac.

I would do the swap first, then if you want, you can swap the master later. You might find that you will use more pedal travel with the rear discs especially if you go to the four piston front capipers at the same time. If you want to get the pedal travel back more to what it was before the swap, then use the 15/16 master.

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With any Hydraulic brake system , the maximum system pressure for the least pedal pressure will result from the smallest master cylinder you can use.

Hydraulic force ratio = slave cylinder piston area/master cylinder piston area

Slave being wheel cylinders

The limit of couse is the smaller the master cylinder diameter the more the pedal will have to travel to displace the required amount of fluid. So when sizing the master cylinder use the smallest you can with out the pedal travel exceeding 75%

I would use the one you have and try that first.


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  • 2 years later...

hi guys,

sorry to dredge up an old post, but i have been told that i need to get the 15/16" master cylinder from a 280Z, i assume that this would be the 1979-1982 280ZX??? did it come on any other 280Z? all the ones i can find online seem to be all 7/8" ones

does anybody have a part number?

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