Make sure to say “ahh” when flushing the brake fluid from your eyes with cold water and use this as your culture guide to what you can expect after the car purchasing haze has worn away.
Braking is essential. Abstractly, it is essential to speed. A terrible and violent philosopher once said “Speed has never killed anyone. Suddenly becoming stationary, that’s what gets you.” In the course of it’s essential nature, to spite it would suggest that you truly only enjoy the opposite in the way a grandmother loves her grandchildren; that at the end of the day, she’s glad they go home with their parents. Is that a genuine love that respects boundaries, capabilities, and is unconditional? In this way, braking is essential to speed. Now that we’ve scared away all the cretins, it’s only you here with me fellow intellectual, free to breath in with your eyes, this narrative brake refresher course for the E30 you will inevitably sell (in the environmentally hopeless future) to raise money for an in-home, emergency CO2 scrubber.
We’ll start from the beginning. Where your foot hits the pedal. This is more labor intensive than it is financially burdensome. Much of our braking journey’s framing device involves chasing down a poor vacuum, evidenced by a stiff pedal that traveled all the way to the end of the master cylinder’s stroke before the car would ever come to a full stop. We replaced almost everything before we finally realized it was a fossilized rubber gasket between the master cylinder and the power brake booster. The moral of the story, before it even begins, is to start small and cheap. A lesson-learned here was to stick to the scientific method. Our symptom was a stiff pedal – indicating a solidly bled hydraulic system – so vacuum would likely be the culprit. So instead of throwing money at the catch-all problem of “brakes” by replacing anything and everything brake related, we should have stuck to variables that were vacuum related and rectified them one-by-sucky-sucky-one. Had we done that however, we wouldn’t have been able to bring our vast knowledge of repair and replacement to you here in this blog, written under the drone of fluorescent whine and rattling air conditioning (of course we didn’t quit our day jobs).
Absolute Power Brake Booster Does Not Brake Absolutely
We won’t use any part’s basic functions as filler. Just how they fit into the story and what you can expect when you try to replace them. If you find that the booster has sucked it’s last suck, then relax; it’s as hard to pull out as you’d think. After this repair, it turned out our 200,000 mile booster was actually sucking, but had re-watched The Brave Little Toaster so many times that the VHS was worn out, so they were both replaced anyway. We used a new one from mom-and-pop local parts shop. Our VHS was ironically replaced with a DVD. This was the priciest part of our learning experience at $196 after returning the core. You’ll have to remove the four nuts holding the rear of the assembly to the firewall by way of 3/8” extensions and a 13mm socket. Fortunately, the one that you’ll find the most difficult to remove, has a coinciding hole drilled through the brake pedal for easy access. Don’t bother wondering if you need to remove the master cylinder to get it out of the way. It’s gotta go. However, if you skip ahead to the sections on upgrading the master cylinder and brake lines, you can disregard that advice. Now, replacing the booster is a pain in the way that changing your bed sheets is a pain. You could just take a shower before you jump into bed to make it feel like the sheets are clean, but that feeling will wear away as soon as your skin dries and hardens again and you’re left with the stretched and worn fabric of your procrastinations. You can disconnect the master cylinder with the two 13mm nuts securing it’s base and do your best to wriggle it away and clear the pushrod from the booster, but the inflexibility of the steel brake lines will stop you plenty shy of any achievement. The lines will have to be disconnected too, facilitating an inevitable bleeding.
Yes, Master Cylinder (E32 Upgrade)
The master cylinder is a different pain. Knowing that you absolutely have to disconnect the lines as a matter of necessity and function makes it easier to ride the waves of brake fluid. The hurt is still there when you’re forced to contort to remove nearly every fastener. Removing the reservoir relieves some of this pain. Just be ready to catch the escaping fluid. Two 13mm base nuts that are most easily removed with a ratcheting wrench on the passenger-side and a regular combination wrench on the other, get it freed from the booster. An 11mm line wrench and a brief persuasion of the righty-tighty (maybe a 1/10th of a turn) before you left-loosey helps get the lines off. If you have the time and materials, this would be a great time to remove your ABS unit, re-route, and re-plumb with nickel-copper brake line. We’ll cover these modifications in later subsections. Once you’ve removed the old master (keep it around if it was still in working condition so you can use it to troubleshoot if you ever have trouble with the new one), pop you’re new E32 750il master cylinder in for a stiffer and slightly more manageable pedal response. We felt like we experienced a shorter throw in the pedal too. You won’t see an increase in power, but if you’re mission is accuracy, make this a top priority like you would the Z3 steering rack upgrade. And for the love of every Dr. Who companion, change the O-ring!
Brake Lines – Don’t NiCopp an Attitude With Us
Whatever you’ve heard about nickel-copper lines is a lie. They’re tough while still being flexible (enough to get the master cylinder free of the booster without disconnecting them), cheap, and can handle the pressures of steel lines up to a negligible margin. If you’re going to remove the ABS unit, which we won’t condone or approve of because it’s necessity varies upon vehicle use, you’ll have to make custom lines anyway. For us, the steel lines didn’t make it through the surgery of removing the ABS pump so this was unavoidable. Right now, we’ve replaced the front lines all the down to a point where we made a previous splice just underneath the driver’s seat. There’s a learning curve when flaring this kind of line, but our rule of thumb was to set our line up in the flaring tool clamp to about 2/3rds the height of a steel line after having done our best to cut it as square as possible. It’s as easy as thinking about pink elephants when you’re told not to, to flare it off-kilter. Hold on to the small plastic brackets that hold the lines in vertical order, and re-use them when sculpting your masterpiece around the edges of your engine bay.
To be continued…