240Z Brake Upgrades

[texasz]

From everything I've researched if I keep the rear drum brakes stock and upgrade the front to the Toyota 4-piston calipers then I should also upgrade the master cylinder to the 15/16 one from a 280ZX.  Question #1, is this accurate?

 

When upgrading the master cylinder to the 15/16 one it seems that this is a direct bolt in upgrade.  One thing I have found is talk about the master vac (booster) also being something that some people upgrade.  Issue with this is that as I understand it the 280ZX (10") will not fit due to the clutch master cylinder (at least without some modification/fab work).  I have also learned that there are TWO different sizes that came in the Z, the 7" which is what is in my car and the 8.5" in the later Z cars.  This all brings me to my next question...I have the 7" booster and plan on doing the 15/16 master cylinder upgrade, will be 7" booster be ok?  What are the pros/cons of keeping the 7" booster?

[S30Driver]

Briefly speaking,  if you change the master cylinder to say 15/16" , it will compensate for the increased volume of fluid to move in the 4 piston calipers, with less pedal travel than if you left the stock MC in the system.  However, the bigger bore MC will require more pedal effort.   (you never get something for nothing)  Therefore, the change to a larger booster compensates for this by reducing the pedal effort back near the oem systems specs.

Hope this helps ...

[texasz]

That's great information S30Driver.  This leads to the other part...which booster should I be looking at installing?

 

IF the 8.5" is the way to go then my next question...does anyone have one they recommend?  How about anyone with experience with this one?

https://jdm-car-parts.com/products/datsun-240z-1969-1972-8-5-inch-brake-booster-upgrade-kit?variant=2376693317641

[RIP260Z]

Texasz,

I am running the 260z (280z for you in US) 2+2 model booster, its bigger as the 2+2 is heavier, especially with 2 extra passengers. There is a graph in the Nissan workshop manual showing the differences in pressure/vaccum.

[AK260]

FWIW, I went S12W callipers and vented Peugeot 505 discs at the front, with mintex pads, but left the 7/8 MC in as I like to make one change at a time and learn about the difference that one change made.

 

The net result is I have never been left wanting for stopping power on track days and spirited road driving. Never any fade.

 

I actually really like the pedal action as it makes it even easier to heal and toe on downshifts. Having experienced it, I personally don’t think it’s worth the hassle to change out the MC, have to re-adjust the rod and/or change the booster.

 

But it’s a case of personal preference.

 

Disc specs ...

 

EBC Part Code: D117

Peugeot 505 2.2 Turbo

 

Year: 79-92

Bolt Holes: 4

Diameter: 273mm

Height (Laid Flat): 43mm

Thickness: (New/Min): 20/18mm

 

UK cost £74 a pair.

 

 Ps. I had to grind 4mm off the fins on the callipers as my 14” wheels have some serious offset and would bind on them.

 

[AK260]

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