Whats my ideal master cylinder size

[BitchinZ]

I have a '77 280Z.  Im going to keep the stock front brakes but replace the rear drums for '83 ZX discs.  What would be the best size master cylinder for me? 

 

I already bought the 1" Wilwood one but after doing more reading it sounds like it might be overkill.  Should I keep it, sell it and get a 15/16 or will the stock 7/8 be plenty?

 

Thanks

Edited March 22, 2013 by BitchinZ

[Josh280z]

You're asking that question here at hybridz? There is no such thing as best, but there is a best for your own personal needs. The rule bigger is better applies to the brake master cylinder.

 

So, that being said; the bigger the master cylinder the less pressure you will have to apply to stop your car.

 

So, why do you think the 1" master cylinder is overkill?

[Miles]

The larger MC will actually  require more pedal force than a smaller MC. The reason for using a larger diameter MC is when larger volume calipers are used such as the Toyota 4x4 vented calipers.

 

If you are keeping the stock front calipers and going to 280ZX calipers on the rear then the stock 7/8 dia. MC should work. Only go to a 15/16 in. or 1 in.MC if the pedal throw is too long. The smaller 7/8 in. MC provides more hydraulic "leverage" then the larger MC such that it will take less pedal force to stop.

 

Better advice: keep the stock brakes. The 280ZX rear disk install is not a performnce upgrade. Do more research in the brake and the FAQ sections before you waste a lot of time and money. Just rebuild and maintain the stock brakes and use  good pads such  as Hawk Blues etc.

 

You may want to bone up on basic brake hydraulics before modifying your brake system as the changes tend to have a domino effect that can make brake performance worse.

 

And no, a proportioning valve will not solve anything with this  particular modification.

[BitchinZ]

I already have a complete 280ZX donor car for the disc setup and I dont want to work on drum brakes.  Those are the only reasons I was going to switch.

 

Are the 280ZX rear discs at least equal to the stock drums on performance or are they a downgrade?

[Miles]

The answer is  here: http://forums.hybridz.org/topic/39435-help-what-brake-options-are-available-for-s30-z-cars/

[ComicArtist]

You should either 

 

A: keep your stock MC and sell me your Wilwood

 

or 

 

B: use the 15/16ths and sell me your Wilwood

 

Like they're saying, the Wilwood isn't going to be overkill but for a simple rear disc upgrade, there won't be much of a braking difference without doing a front upgrade. Like they're saying, rear discs are more of a convenience and cosmetic upgrade than performance. Rear discs don't really require any more pressure to activate than the stock drums.

 

Either way, you should sell me your Wilwood. For realz

Edited March 23, 2013 by ComicArtist

[m1ghtymaxXx]

I've got a 77 280z with the Wilwood 1" MC and bone stock brakes front and rear. When I bought the car the MC was trashed, and since I had future plans of doing the Toyota front brake swap I figured I'd futureproof with the Willwood master cylinder. I've street driven and autocrossed with this setup with no issue, but I never drove the car with the proper master cylinder, so I don't know how it compares. The way I see, the steering is already heavy as hell, now the brakes just match in feel

 

Keep in mind the 280's have bigger boosters than the earlier cars too, I have no problems looking up the wheels.