So i get back from a 8 month work travel trip and i go to start my crx... as i pull out of the driveway i notice i have no brakes! Turns out the resovoir is empty.... Which is weird. I bled my whole system a little over a year ago and its been perfect till now. I refill the system, try to bleed the system, and i still have a soft pedal. I conclude that maybe my master is bad. I couldn't find any leaking in any lines around the car. I decide to swap the booster and master together just because.... I get a new master from a 91 civic 4 door (for the larger piston size) and after i put everything together, the first 3/4 of the pedal has nothing, while the last 1/4 has the brakes engaging. I take it to a shop nearby and they said i need new lines, calipers, and wheel cylinders. I didn't believe them at all, but i was in a crunch so i let them do the work. After the work the car did the same thing.... surprise! I told them about the adjustible nipple on the booster, then they messed with that and all seemed to work.

Untill i had to emergency brake on the highway. I hit the brakes hard and noticed the pedal went to the floor and the brakes were engaged like 50%. I take it to a different shope (on a cross country trip right now) and they find that the booster itself is broken. The shaft somehow broke itself and wasn't engaging the master cyl all the way. So they replace the booster and now i'm back to 75% of the pedal doing nothing, with the last 25% providing all the braking, though this time i get normal braking performance and can lock up the fronts. The 2nd shop i took it to said they weren't supposed to adjust the nipple on the booster which was why it broke.... So now i'm back at square 1. I'm at a loss on what to do and i'm afraid if i adjust that nipple my booster will break a gain. Did i get a bad master? What gives?

I should probably also mention that my booster is the 8.25 dia booster from a civic, its not the smaller diameter booster that the crx HF is normally equipped with.

 

Are you still having to add fluid? If so, find where it is leaking - make sure the first shop did change the wheel cylinders. Make sure all the flare nuts are tight at the wheel cylinders and the proportioning valve. Is there a hole in one of the rubber lines? Blown out seals on the calipers?

If you aren't losing fluid, I would re-bleed the system yourself. Buy a large bottle of DOT 3 brake fluid (it's not very expensive) and bleed all 4 corners according to the manual until you have clear, new fluid at each corner. Other than that, I'm not sure what to suggest.

 

Since you have decided to "upgrade" your master cylinder & booster, your brake system will never feel like it used to. You really only need to upgrade those two parts if you also upgrade your brakes all the way around. A braking system is all meant to work together. It sounds like something else is definitely going on but you need to keep in mind that your pedal will now always have less travel than it did before until you upgrade the rest of the system (disks in the rear & I believe larger calipers up front, as well as a a different proportioning valve).

 

No leaking fluid since i refilled the system, before i decided to replace stuff. I've even tightened all the nuts around the hardlines. No leaks that i can identify. The shop replaced ALL of the rubber lines as well. The braking performance is actually fine, its just that i have to go through 70% pedal travel to get there. Though once i hit that 70% mark the brakes feel 100% normal in travel, force, and performance.