If you've spent any time behind the wheel of a classic Chevy, you know that installing a 1966 impala disc brake conversion kit is usually the first major upgrade owners look into after getting the engine running. There's a specific kind of "excitement" that comes with driving a heavy, full-size B-body car equipped with four-wheel drum brakes. It's the kind of excitement that involves a lot of prayer and a very heavy right foot when someone in a modern SUV cuts you off on the highway. Those old drums were fine for cruising at 40 mph in 1966, but in today's world of distracted drivers and sudden stops, they're just not up to the task.
The 1966 Impala is a beautiful machine—long, wide, and sleek. But it's also essentially a two-ton living room on wheels. When you're trying to bring all that mass to a halt, heat is your biggest enemy. Drum brakes are notorious for holding onto heat like a sponge holds water. After a few hard stops, you'll feel the pedal get soft, the car might start pulling to the left or right, and suddenly you're wondering if you're actually going to stop before the red light. Switching to a disc brake kit changes the whole personality of the car, making it feel way more planted and, more importantly, a lot safer.
Why the Swap Makes So Much Sense
It's easy to get caught up in the "keep it original" mindset, but when it comes to safety, originality is overrated. The biggest issue with the stock 1966 setup isn't just that it's old; it's the design. Drums don't shed heat efficiently. When they get hot, the metal expands away from the shoes, and you lose your stopping power. It's called brake fade, and it's a terrifying sensation.
A modern disc brake setup works differently. The rotors are exposed to the air, so they cool down almost instantly. Even a basic 1966 impala disc brake conversion kit will provide more consistent stopping power than the best-adjusted drums on their best day. Plus, discs are self-adjusting. You don't have to crawl under the car with a brake spoon every few months to make sure the shoes are hitting the drums evenly. You just step on the pedal, and the car stops straight and true every single time.
What You'll Find in a Typical Kit
When you start shopping for a kit, you'll notice a huge range of options, but most of them include the same basic components. You're looking at new rotors, calipers, brake pads, and the mounting brackets to hold everything to your existing spindles. Most kits for the '66 Impala are designed to be "bolt-on," meaning you don't have to be a master fabricator or a professional welder to get them on the car.
A lot of the better kits also come with a new master cylinder and a proportioning valve. This is a big deal. If you try to run disc brakes using an old drum-style master cylinder, you're going to have a bad time. Discs and drums require different amounts of fluid pressure. The proportioning valve is the "brain" of the system; it makes sure the right amount of pressure goes to the front versus the rear so your back wheels don't lock up and send you into a spin the first time it rains.
If you really want to do it right, look for a kit that includes a power booster. A manual disc setup is still better than manual drums, but if you want that modern "easy-stop" feel, a vacuum booster is the way to go. It makes the pedal feel light and responsive, which is exactly what you want when you're navigating through city traffic.
The Wheel Clearance Headache
Before you pull the trigger and buy a 1966 impala disc brake conversion kit, you need to check your wheels. This is the one thing that catches people off guard more than anything else. Back in 1966, 14-inch wheels were the standard. The problem is that most modern disc brake calipers are too bulky to fit inside those old 14-inch steelies.
If you're dead set on keeping your original 14-inch wheels and hubcaps, you have to be very careful. There are a few "zero-offset" or "small-diameter" kits out there designed specifically for this, but they're less common. Most people find that this is the perfect excuse to upgrade to 15-inch wheels or even something larger like 17-inch Rally wheels. Not only does it give you plenty of room for the brakes, but it also opens up a much better selection of modern tires. Just keep in mind that if you buy a big-brake kit with 12 or 13-inch rotors, you're almost certainly going to need 17-inch wheels at a minimum.
Getting Your Hands Dirty with the Install
Installing one of these kits is a great weekend project. If you've got a floor jack, some jack stands, and a decent set of wrenches, you can probably knock this out in a Saturday and Sunday. The hardest part is usually just getting the old, crusty drum hardware off. Those parts have likely been on there for decades, so be prepared to use plenty of penetrating oil and maybe a little bit of heat from a torch if things are really seized up.
Once the old spindles are bare, the new brackets usually bolt right up. You'll slide on the new rotors—which, by the way, always look awesome when they're brand new and shiny—and then bolt the calipers into place. One tip: make sure you don't let the calipers hang by the rubber brake hoses. Use a zip tie or a piece of coat hanger to support them so you don't damage the lines.
Speaking of lines, you'll almost certainly be doing some plumbing. You'll need to run new lines from the master cylinder to the proportioning valve. If you aren't comfortable flaring brake lines, this might be the only part of the job that feels a bit daunting. However, many kits come with pre-bent lines that take the guesswork out of it. Once everything is hooked up, it's just a matter of bleeding the system. Having a friend help you pump the pedal makes this go a lot faster, or you can pick up a one-man bleeder kit if you're working solo.
Power vs. Manual: Which Way to Go?
I get asked this a lot: "Do I really need the power booster?" The answer depends on how you use the car. If you're building a stripped-down drag car where every pound counts, manual discs are fine. They give you a very firm, communicative pedal. But if the car is a cruiser, go with the power booster.
A 1966 Impala is a big, heavy girl. Having that vacuum assist makes the driving experience so much more relaxing. You can stop with just a light touch of the toe rather than having to stand on the pedal with both feet. Most 1966 impala disc brake conversion kit options offer a booster as an add-on, and in my opinion, it's worth every penny. Just make sure your engine is producing enough vacuum to run it. If you've got a really aggressive cam with a lot of overlap, your vacuum might be low, and you might need an electric vacuum pump or a "hydroboost" setup instead.
Final Thoughts on the Upgrade
At the end of the day, upgrading your brakes is about peace of mind. There's nothing quite like the feeling of driving your classic down a winding road or through a busy town and knowing that the car will actually stop when you tell it to. It makes you want to drive the car more often, which is really the whole point of owning one, isn't it?
A 1966 impala disc brake conversion kit is probably the best bang-for-your-buck safety mod you can do. It doesn't just improve the stopping distance; it improves the "driveability" of the car in ways that are hard to describe until you feel it for yourself. No more pulling, no more fading, and no more worrying about whether the car in front of you is going to slam on their brakes. You just get to enjoy the ride, the sound of the V8, and the look of that classic Chevy dash. If you're still running those four-wheel drums, do yourself a favor and make the swap. Your Impala—and your nerves—will thank you for it.