First a long-winded story. A few years ago I performed an SE-i rear disc swap on my car. The swap was okay. I didn't notice much improvement, honestly. The pedal was slightly softer than before, but braking performance remained the same. Worse, the prop valve seeped at all the flare fittings. I fiddled and farted with it from time to time and managed to make it a lot worse. The flare nuts were distorted and mangled from where I tried to over-torque them (more on those later). The fluid made an oily mess everywhere and I was buying a lot more brake fluid than I wanted to. I finally figured out that the flare seats in the valve were worn out and needed to be replaced. I did a little write-up about it here:
Sadly, you can't replace the flare seats without replacing the entire valve. Problem: SE-i prop valves are haaaaard to find, very old, and not likely to be better than what I had. I opted, instead, to replace my valve with an adjustable aftermarket unit from Wilwood.
The swap has been everything I hoped for and much, much more. I didn't do much adjustment and didn't do it with any precision. Pretty much I turned the wheel all the way to even, backed off a random turn and went for a test drive. Without a trace of hyperbole, my car's braking was completely transformed. The pedal feel was much more solid. Engagement was so much more precise and predictable. Stopping power increased amazingly. It was as if someone had turned on the other half of my brakes. Like I said, I was underwhelmed with my rear disc swap initially. The only change I noticed was that the pedal was a little more mushy than before. Pretty disappointing for all the work involved. With the prop valve, it was as if I had upgraded the entire braking system. Everything felt fresh and new, tighter and more integrated.
I'm doing this write-up in case anyone else wants to do this too.
Here is my install.
I mounted the new valve to the stock location with a single bolt using one of the old bolt holes. It's held up great for the year it's been there.
There are a number of important differences between the Wilwood unit and your stock Honda valve that you'll want to know about and plan for.
- The Wilwood is SAE; the Honda is metric. Your existing lines will NOT thread into the Wilwood valve.
- You will have to modify/replace some of your existing brake lines.
- The Wilwood is biased front/rear; the Honda is staggered.
- The Wilwood has 5 ports; the Honda has 6.
The biggest part of the job will be re-working the brake lines. You'll need:
- Bulk hard line
- Flare tube nuts
- A cheap bender
- A cheap flaring kit
- I would also highly, highly recommend both a metric 10mm flare wrench and an SAE 3/8" flare wrench. They are different and Honda's flare nuts will punish you for using the wrong one. (They'll punish you anyway, but not as much.)
- Finally, pickup enough DOT3 or 4 (not 5) brake fluid to bleed the brakes when you're done. A quart is usually sufficient.
I picked up this really crappy bender from O'Reilly for cheap...
...then I rented their crappy flaring kit and kept it.
My lines look awful, but they work.
Our cars use 3/16" brake line. For line, I picked up some PVF coated line from Summit.
There are 3 different kinds of line you can choose:
- Mild steel lines - they are cheap and easy to work, but they rust quickly. In general, I wouldn't recommend them unless you're stranded and broke.
- Stainless steel - they are expensive, brittle, difficult to work and don't rust. These seem to be the hot rodder's choice.
- PVF coated lines - they are mild steel with a plastic coating. They are easy to work, fairly cheap and resistant to rust. They are also what Honda put in these cars originally. The OE lines have lasted very well, and I wanted my new lines to match them, so I chose this.
- There are also some proprietary alloy type lines that are very, very easy to work, though expensive and difficult to find.
Again, your existing flare nuts are metric and will NOT work in the Wilwood valve. You'll have to cut off your existing nuts and replace them with SAE nuts. Honda used the lowest-grade pot metal imaginable for the flare nuts on these cars. They are barely adequate for the 11 lb-ft torque spec listed and will round over at even 1/2 lb-ft beyond that. Hell, they'll round over when you're trying to loosen them with a flare wrench. Always have a Vise-Grips on hand when dealing with these terrible nuts. Summit has a bazillion different options for replacement nuts and I would say choose good ones. I had to torque mine down pretty hard to get them to seal and having robust flare nuts made that possible. If Honda had specced decent nuts, I might have been able to over-torque them and probably save the old SE-i valve.
You'll want to plan your lines carefully. Flaring lines is a slow, tedious process, especially with a crappy flare tool, but how-to videos are abundant on YouTube, so use them. Expect to have some failures, and buy extra line to make a few practice flares before committing to the long lines to the rear that are difficult to access and require you to pull the interior to replace. Bending line is also a tricky art that I clearly haven't mastered yet. I just accepted that they look terrible and since they are largely out of sight, I won't worry about it until I do a major brake upgrade and refresh. At that time, I'll probably choose stainless line.
The front lines run along the bottom of the firewall in the engine bay. For some reason, Honda chose to place the prop valve on the opposite side of engine bay from the master cylinder. Thus, 2 lines run from the master cylinder, across the engine bay to the prop valve. The lines to the calipers branch off from there with 1 line running back across the engine bay to the left front, another going to the right front, and two lines going through the firewall, then the passenger compartment to the rears. Honda used about 3x as much line as they could have by doing it this way. I don't know why.
As I listed above, the Honda valve has 6 ports, using one port for each rear caliper. The Wilwood has 5, splitting one port to both rears. You'll have to splice in a brake line tee to accommodate this.
Because installing this tee will give you some extra rear line to play with, it will keep you from having to tear out your interior to replace those rear lines. Yay! You'll just have to cut and flare them in place to install the tee wherever you want. Here's a pic of mine hiding beneath the black box.
And here are the rear lines going through the firewall. You don't want to replace them if you can avoid it.
I replaced all my front brake lines when I did this job. I removed the air intake box and charcoal canister, then loosened the black box so I could move it out of the way. Everything was easy to get to this way and the whole install was an easy Saturday job.
As mentioned, my lines look terrible and that's largely because the PVF lines are so soft. The tubing bender makes decent bends, but the soft line bends much farther out as you make each bend. Thus, the parts that you want to stay straight will still bend, leaving you with a goofy looking line that doesn't line up with the other lines. This is just aesthetics, of course, but still the kind of thing that bugs me. You can easily bend them back by hand, but it's a lot harder to make lines straight than to bend them initially. Stainless lines would probably be easier to get right because they are so rigid. A better bender would also work. If aesthetics are important, then go with stainless lines, a better bender, or both.
A word about bias - On most cars, master cylinders have 2 chambers. On an American car, one of those chambers will be larger than the other. The large chamber puts out more pressure and routs to the front brakes. The small chamber routs to the rear and puts out less. If one chamber loses pressure, you'll be stuck stopping the car with either the front brakes only or the rear brakes only. Seeing that the rears have only 40% the stopping power of the fronts, getting your American car stopped with them alone will be difficult. Our master cylinders are different. They have 2 equal sized chambers that put out equal pressure. Each chamber runs to one front caliper and one rear caliper. The calipers are also staggered so that a front caliper on one side of the car is paired with a rear caliper on the opposite side of the vehicle. Honda opted for this as a safety measure so that if pressure is lost in one chamber, the braking force will still be roughly even, though half as strong. In practice, you'll probably never be in a position to appreciate this 10% gain, and I'm not sure it's worth the added complexity. Still, that's how things are.
Why am I bringing this up? Because the Wilwood is a front/rear (American) biased prop valve, not the staggered setup like Honda. I worried that this difference would cause some kind of problem, but so far everything has been brilliant. I mention it for the detail oriented folks who like to know about such things before they embark on the repair. You'll be moving from a staggered bias brake setup to a front/rear and it will be brilliant. Don't worry, it will be awesome!
That's about all I can remember about my install. Feel free to post questions or amplifications below.