Continued from Part 1
Hot, Local Brake Hose in Your Area
A focal point of our brakes, and ultimately our racing styles, is our $35 Wilwood adjustable brake proportioning valve. Keeping the system free of variability so that we can be assured that our proportioning valve is truly giving us the courtesy of a reach-around is key to setup and execution. With a fresh booster, fresh master cylinder, no ABS pump (and thus, almost zero potential for trapped air in the lines), one of the last things that needs to be tightened up in the hydraulic system is the hoses. Stretch in these components means fluid breaks out into the extra volume under pedal pressure and you lose consistency during its travel into the darkness. At this point in our Shakespearean tragedy of a racing career, we’ve only replaced the fronts with the braided stainless steel ones we picked up from a guy that owned a lifted Mazda Miata and an M40-powered touring E30 down in Nashville on a work trip. Not buying it when it was offered to us is one of our greatest and most dishonorable decisions we’ve ever made. Our family lineages will likely be cursed as a result.
The rears will see their due when we pull the rear subframe for it’s refresher course. Installation was simple after replacing the front lines. It’s not terribly difficult to install them on old lines, but make sure you have the right tools because the old fatigued metal of the fittings won’t survive a line wrench that is “close enough” in size.
49-51-49, The Ideal Brake Proportioning
We did most of the hydraulically related work over a matter of months. At times, we’d say things like “Good enough”, “we can’t see it from your mom’s house”, or “We’re here for a good time, not a long time.” The OEM proportioning valve was unnecessarily difficult to reach with the master cylinder and booster in place (parts we had already replaced by this time), so we chose to abandon it in-place and re-locate the new Wilwood adjustable one to an easily accessible position. We bracketed ours to the ledge that the old air box used to sit on with the convenient mounting holes built into the valve’s body. We might cover the basics of installing a new proportioning valve in absence of an ABS pump in a later post. We highly recommend this valve because it’s inexpensive and vastly adjustable; up to 49% can be split to the rear.
The Easy Part – Calipers, Pads, and Rotors
Your front and rear calipers are going to be the easiest components to address if you stick to the originals. Basic blank rotors were satisfactory as we were looking for longevity over anything else. We had to use a simple rebuild kit for our rears because at the time, coming across cheap used ones was difficult. Five years later, they’re still squeezing. Otherwise, if you need new front ones like we did, you can get them from any parts store easily and inexpensively. There’s an argument out there about Girling vs. ATE calipers but we know nothing of it because we’ve only recently learned things like times-tables and simple grammatical concepts. Too much book learnin’ involved. Hawk HPSs have proven to be more than enough for the low pressures of autocross. If we have more than an approximately 60% split on our proportioning valve, the front wheels lock under heavy braking. They’re not as squeaky as other pads either, and it seems that they like to be hot so whenever these wear out, we’ll be looking for something that works better with the short stints in autocross. Conversely, that was helpful when we rode the north course at the Autobahn Country Club. Keep the guide pins greased like any other passenger car brake system.
Ever heard of 6-Minute Abs? How about no ABS at all?
Come back in time with me as we recount the horrors of chasing the source of our poor vacuum braking performance. After replacing the power brake booster and master cylinder, and bleeding the brakes a necessary amount of times in between, we could tell as immediately as we hit the brakes to slow down our decent into “madness” (a fun and stable nickname we have for our slightly sloped driveway), that there was no joy. The pedal was still stiff but there was no power behind it. A wavering prerogative to make the car simpler, and coincidentally, lighter, inspired the removal of the ABS pump, located just behind the driver’s-side headlamp assembly. The dashboard had been removed in the past to chase a faulty ground and a connection for the ABS system had remained mysteriously and unapologetically unaccounted for. The warning light on the dash was our only indication since the poor vacuum meant we couldn’t road-test for ABS function. Removing it was a simple decision, but the labor was unwelcomed.
It was old, but the lessons learned were invaluable. Among them, on the recommendation of a teammate, tightening brake line fittings slightly to help free them before loosening them completely; like gas-lighting a small child by telling them that you’re going to a fun theme park, but in reality are taking them back to the orphanage. Once the pump was out of the way, we re-plumbed the lines with nickle-copper brake line so that the front-calipers port on the master cylinder was split between the two front with a t-fitting and the rear port plumbed directly to our brake proportioning valve. Once it was bled, another backwards trip into madness was made, and as you might have suspected, foul language was used. That was a particularly frustrating day in retrospect. We’d spent nearly ten hours, much of it soaked in brake fluid after we’d run out of latex gloves, routing, bleeding, spilling, swearing, eating, and aching. However, the next weekend made it seem like it had all been a bad soap-opera-series-finale fever dream when we finally realized the master cylinder O-ring was bad when we pulled it forward to inspect the paper filter that mated the flat surfaces of the master cylinder and power brake booster.
We awoke wet from that dream. From sweat this time. Never had we been more satisfied to tear down our local frontage road Nurburgring simulator. Chirping like birds in heat, our tires skipped across the faded concrete under the weight of our feet on the pedal.
Thanks for reading! New posts on Sundays.