The constraint for larger boosters on the 240Z is the space between the throttle pivot bracket and the clutch slave on manual transmissions cars.
The larger 280ZX booster fits automatic 240Z cars because there is no clutch MC in the way.
I used the 8.5 inch 280Z booster. See picture for fitment.
The 280Z booster bolt pattern differs slightly from the 240Z which requires re-drilling the mounting holes in the firewall.
On SBC V8 with T5 transmission equipped 240Zs you can to get a little more clearance between the throttle pivot bracket and the clutch slave by using Wilwood clutch MC instead of the Tilton clutch MC. The Wilwood clutch MC is much more compact.
Bro I tried that like crazy and I'll share thst k order to get the zx booster in there BOTH the throttle linkage part Woodhaven to be moved and the clutch MC would also have to be moved about an inch to the right to make room. Still lots the zx booster laying in the garage from the z zxt donor car incase I ever pull the trigger... Although highly unlikely. Unless the 280z booster/15/16 Mc set up feels too much of a pain to stop
On the early 260z, I can attest that the 280zx flipped upside down without the spacer does fit just fine (manual car too). Not sure if my firewall/Clutch layout is the same as the 280z, probably. but could also be an early 240, late 240 thing (post 73?).
I run the 280zx booster, and the beauty then is that the 300zx (z32) or hardbody (4x4) cylinders fit just fine as well. I grabbed a 1" hardbody Master for like $35 on rockauto that had an arrangement of outputs I liked. I deleted the stock PV (replaced with 2 couplers) and the stock pressure switch. Plumbed in a wilwood knob adjusted PV. Had to make custom lines to go from metric to imperial fittings, but i was making a lot of lines anyways.
I was referenced early in this thread regarding apparent Bias with the vented 4x4 setup and 280zx rear (early 280zx, though it's the same piston diameter).
For starters, I really like the brake pedal feel I get. I'd say it's a touch firmer than most stock brake systems in your everyday car, but doesn't required excessive effort. Plus I'd rather a firm feel than sponginess. Also, my free play and grab with the 280zx booster and 1"MC is pretty good. There is a tiny bit of movement before it grabs, but I'd say it's less than my fx45 and about the same as my forester XT.
Regarding bias, I have still yet to test out bias/locking characteristics in the wet now that the brakes are well bed in. I went with the setup mainly because when I did the math, the 4x4 vented front actually has about the same piston area as the 280zx single piston front brake does. I therefore thought it'd have about the same bias as that car and with a little help from the PV I could get more rear bias.
Car stops very well, but I'd say I haven't driven (or emergency braked rather) enough cars to have a relevant opinion. It also doesn't help the argument considering I have 225ish autocross tires on a 2500lb car, so it's going to stop a lot better than most anything even with a sub optimal bias. For the street, I have no complaints. The pedal feels nice, comes to a halt very fast, and doesn't fade after the 2-4 stops I might make in a spirited drive down some back roads. Plus the looks of my gold painted 4x4 calipers, nicely working E-brake, and easily serviceable rears is a big plus.
If down the road I get into more racing and really want to dial in bias, I could look at trying a larger rear rotor and accompanying caliper bracket, or play with pad compounds.
Also, someone mentioned wilwood PV only goes to 57%. But i was under the impression that with it fully cranked, it was 1:1 ratio and only backing off the spring/knob gives a maximum of ~57% rear bias reduction.
Any questions about my setup, just ask!
Edited by mtnickel, 4 weeks ago.