260Z/280Z booster in a 240Z - it can be done

[ezzzzzzz]

I'm having problems my rear disc brakes not working well so I'm in the process of replacing the possibly faulty MC and modded the NP-valve to fully separate the front and rear brakes into individual systems. (http://forums.hybridz.org/showthread.php?t=114918). I thought I'd try to install the larger S30 booster for less pedal effort at the same time since the brakes were much firmer than with the stock disc/drum setup. Several posts said it couldn't be done but it appeared no one had actually tried and failed. Since I had a spare 8.5" booster I thought I'd give it a go. First, the retaining bolts are spaced approximately 1" further apart on the horizonal but the vertical spread is identical at 2.75". It's really in metric but I used a basic tape measure. I did an eyeball alignment to mark the wider spaced holes to either side of the existing holes in the firewall. I then looked under the dash to ensure there was room for the nuts/washers for the new pattern. Next came the drilling. I drilled the holes in steps and then did a little bit of filing with a small round file to get slip fit of the booster. Oh yeah, I also had to slightly bend the brake and clutch lines to clear the booster. An application of sticky weatherstrip goop will seal the new booster from water leaks. The lip of the booster was lighty tapped in near the clutch MC but it may have cleared anyhow. There was ample room at the throttle bracket. I only wish I'd made a template for the holes to guide me. Damn my lack of patience! The attached photos tell the whole story.

[JimmyZ]

Holy cow! I was told by all my buddies that it was a direct bolt in. (Possible difference between HLS and HS? Not likely but possible) Kudos for your mods. It should really stop on a dime after you're done!

[ezzzzzzz]

I installed the bigger booster and a rebuilt MC this morning. My 10 y.o. girl helped me bleed the brakes (that's cool!). The brakes were upgraded to the 280ZX front calipers/300ZX vented rotors and 240SX rear calipers/300ZX non-vented rotors. The 280ZX NP-valve was modded to completely separate the front and rear systems. I took it for a spin and the brake performance is fantastic. It will come to a halt very fast. The pedal is still firm but not like before. My girlfriend could brake it without too much complaint. I'm pleased with the outcome. I'll have to drive it more to determine if a variable proportioning valve will be needed but I'm doubting it right now.