What is the best upgrade for the Master Cylinder?
From RPRWiki
The '88-'91 Prelude MC (15/16" diameter) fits right up to the stock lines. Perfectly. CarParts.com and WrenchHead.com have good prices on rebuilt units, FWIW. The end that fits into the booster requires a little machining, though. It's aluminum, so a hand file and an hour does just fine. I don't think power tools would be any better, BTW. TIP: If possible, I would recommend you secure the MC in a vice during the machining (and the initial bench bleeding). I would bet that would cut your time in half. The part of the MC that fits into the stock power booster is about 3/16" thick, it's a cylinder with a 15/16" inner diameter. You have to machine the outer 1/8" to make it fit. All it takes is patience and a bastard file. Use some blue RTV sealant as a final gasket and you're done. The MC is obviously slightly thicker than the stock one, but not appreciably longer. As I mentioned above, the brake line fittings are in exactly the same place as the stocker. The fluid reservoir is quite a bit wider, but with the stock fuel injection, there were no clearance problems. The reservoir is not appreciably taller, as I remember. There were also no clearance problems with my aftermarket strut bar. TIPS: When you buy your MC (or pick it up at a junkyard and rebuild it You), buy an MC bench bleeding kit. I got mine at PepBoys for next to nothing. It's just a couple of bits of plastic and a few instructions. I had to ask for it at the parts counter, though; it wasn't on the floor. Also buy some brake fluid-- get DOT3 or DOT4, DOT5 is not compatible with the factory system. I recommend going to the Ford dealer (yes, the Ford dealer) and buying some of their Ford HD Brake Fluid. They may have changed the name in the past month or two, but whatever they give you is the right stuff. If you're anal like me, you should consider flushing your brake system during this process. DOT3/4 fluid absorbs some water, over time. You'll want to bleed your car at all four corners about a week after the install. That'll clean out any last little bits of air. It wasn't until the final bleed that I got the maximum benefit.
There is also a direct bolt on 7/8" MC from an 1985 Honda Prelude 1.8L 1829cc L4 2x1BBL. Raybestos P/N: MC39705.
