17 October 2006

Hydraulic Brake Maintenance and Makeover

Brakes are one of the most important systems on a collector car. Your car may run excellent, but if it doesn’t stop the same way, it can’t be driven safely. Most pre-1970 collector cars lack modern safety devices like a dual master cylinder, antilock brake system (ABS) and disc brakes. Certain upgrades to original braking equipment can greatly enhance the safety of classic cars. Let’s review how hydraulic brakes work and see how we can make them even better.

When you hit the brakes, several things take place. The pressure you apply to the foot pedal is transmitted to the brake master cylinder. (If you have power brakes, it goes through a vacuum booster first, and then to the master cylinder.) The master cylinder turns the pedal movement into hydraulic pressure that travels through metal brake lines and rubber brake hoses to the wheel cylinders. Pistons in each wheel cylinder move friction pads (brake shoes or disc-brake pads) against a metal drum or rotor to stop the wheel from turning.

Your brake shoes (or pads) and drums (or rotors) must be in good condition. Finding such parts for old cars used to be quite difficult, but there are now companies specializing in some of the lost arts like re-lining shoes and turning brake drums. A Minneapolis firm named Brake & Equipment Warehouse (www.brakeplace.com) stocks over 45,000 vintage brake parts from brand-name manufacturers. This company also turns brake drums, although it’s likely you can find a local repair shop or auto parts store that still does this simple operation.

When it comes to upgrading the mechanical operation of your brake system, there are limited options available. If you own a Corvette or Mustang, you might be able to find racing-type sintered metallic brake linings or high-performance disc brake calipers or rotors. But if you’re working on a Stanley, Stutz or Studebaker, just finding new parts is probably enough of a challenge.

Brake system hydraulics, on the other hand, can now be upgraded on any car by having the master cylinder and wheel cylinders sleeved with stainless steel. In addition, pre-bent “never-rust” stainless steel brake lines are now available for many old cars. Many hobbyists who worry more about safety than originality are also switching to braided stainless steel brake hoses, which work well and are easier to install than even pre-bent lines. The use of silicone brake fluid always stirs up a bit of a debate.

Routine Maintenance

Before discussing any upgrades, let’s get into routine maintenance of your brake system hydraulics. Even if you prefer not to upgrade, inspecting your original-equipment brake lines and hoses on a regular basis is still important. Check for nicks, fluid leakage, kinks and rust on the brake lines. Large build-ups of road grime can trap moisture, so you’ll want to clean any of those away before problems begin.

Compare the design of your system with illustrations in your shop manual. One hobbyist recently had a leak develop in the brake line on his ’53 Pontiac. He looked for a hole where the leak occurred and couldn’t find one. When he ordered new, pre-bent stainless steel lines from a company named Classic Tube www.classictube.com, the catalog said the car should have five lines. That agreed with a picture in the shop manual – but the car had six lines.

Someone had replaced a single long line that ran from front to rear with two shorter lines joined in the middle. The repair took years, but the non-factory joint in the middle is where the fluid ultimately leaked from. This suggests that the factory engineers knew what they were doing when they designed a five-piece system back in 1953.

Regarding the hydraulic system, check the flexible brake hoses for deterioration. This will usually show up as cracks in the circumference of the rubber hose. Hoses can also be sliced and nicked by road debris. If there is any sign of brake fluid leakage, the hose will need to be replaced. Replace any line or hose that shows significant deterioration. The brake fluid moves through these conduits under extremely high hydraulic pressure. Any weakness in the system can cause a failure and lead to a serious wreck. Our friend with the Pontiac was driving 60 mph a few minutes before his line blew.

Even do-it-yourselfers may need some professional advice when installing brake lines. You can save money by obtaining the parts and doing the “grunt work” yourself, but an expert can give you tips on snaking them along or through the frame rails and making leak-free connections. For instance, you may have to drop the Pitman arm to get the brake line that runs down the frame rail into proper position. The professional will know something like that.

While the installation of brake lines might require some special skills, experience and tools, most do-it-yourselfers should be able to replace a brake line if the old parts come apart easy enough. Basic hand tools will suffice for most of the work involved, though you’ll need a 6-point flare nut wrench. This type of wrench is almost closed but has an opening large enough to slip over the brake line. The six-pointed end fits snugly on the brake line fitting, which is made of relatively soft brass. The snug fit keeps it from ruining the fitting.

Tech Tip: A $3 cupcake tin makes a great storage tray for small brake system parts.

The car will have three hoses if it has a solid rear axle housing. One will run to each front wheel cylinder and one will be at the rear. This line will be connected to a junction block on the axle housing on one end and to a brake line, held in a frame bracket, at the other end. Cars with transaxles will have two hoses up front and two in the rear. If one front hose is bad, replace both. If you have two rear hoses, follow this advice, too. On cars with disc brakes, the hoses will run to a caliper rather than to a wheel cylinder.

The basic steps involved in replacing a brake hose start with securing the car so it won’t roll. If working on the ground, use the parking brake and put chocks under the wheels on the side of the car opposite where you’re working. If working on a lift, follow the lift maker’s instructions to firmly secure the car. Use an open-end wrench on the brake hose fitting at the frame bracket that holds the hose to the frame of the car. Use your 6-point flare-nut wrench to turn the brake line fitting at the frame bracket. Once the fitting is loose, hold the open-end wrench to the brake hose fitting, unscrew the brake line fitting and work the fitting back and fourth a quarter turn until it freewheels. Then unscrew it from the brake hose.

Use a hammer and punch to remove the horseshoe clip that holds the brake hose fitting to the frame bracket. Tap against the bent over top edge of the clip until it comes loose. Pull the old brake hose off the frame bracket.

With the open-end wrench, work the brake hose fitting loose on the other end of the hose where it attaches to the wheel cylinder or caliper or junction block. You may need to use a spray-on rust buster. Remove the old hose. Obtain the proper replacement hose or have one made. Attach the new hose to the wheel cylinder or caliper or junction block by reversing these steps. Now, position the other side of the hose in the frame support bracket. Push it through the bracket and hold it in position on the other side of the bracket with the horseshoe clip, which you can drive over the depression in the hose coupling with a mallet or hammer.

Insert the brake line fitting into the brake hose coupling and tighten with your 6-point flare-nut wrench while holding the brake hose fitting from turning with your open-end wrench. Bleed the brakes. Once everything is reassembled, check that everything is tight and carefully give the car a road test. At first, test everything at low speed, so the emergency brake can stop the car if there’s a problem.

Hydraulic Brake Upgrading

Upgrades can be made to virtually any classic car that uses hydraulic brakes. Having the master cylinder and wheel cylinders sleeved with stainless steel is the first of these improvements. A leaky master cylinder or wheel cylinder is usually caused by rust and pits forming inside the cylinder bore, especially during long periods of storage. The pitting allows brake fluid to leak around the rubber cups on the pistons. Sleeving the bores with stainless steel eliminates the possibility of rusting. If you visit www.brakeplace.com you’ll be able to see the machines used to do this and how it is done. Apple Hydraulics (www.applehydraulics.com), White Post Restorations (www.whitepost.com) and Stainless Steel Brakes (www.ssbrakes.com) are other companies that offer this service.

If you’re going to the trouble and expense of sleeving the cylinders with stainless steel, why not go all the way and get a set of stainless steel brake lines? These are more expensive than standard steel lines, but the advantage is again that they will never rust. That means that your brake lines will probably last forever or for at least as long as you own the car. You won’t have to redo the brakes every 5 to 10 years.

Some restorers are replacing brake lines with braided stainless steel hoses. The advantage of this modification is that the flexible braided hoses are a lot easier to route along the chassis than solid brake lines. They also look great, which is why street rodders and muscle car builders like them. However, they’re a variation from OEM equipment and will decrease the originality of the vehicle. In addition, they could affect your insurance coverage, so be sure to check.

We alluded to silicone brake fluid (Dot 5 fluid), and we’ll admit that some hobbyists swear by it and others swear at it. Conventional (Dot 3/Dot 4) brake fluid is hydroscopic, meaning it can absorb moisture. Silicone (Dot 5) brake fluid doesn’t absorb moisture, which also reduces rusting and corrosion inside the brake system. However, some hobbyists say that they have experienced problems with brake light switches and rubber parts when silicone brake fluid is used. U.S. Army tests that the author studied years ago support positive claims made for silicone brake fluid. This fluid is in two sports cars I own that were stored for many years. On both cars, the brakes work perfectly, but that doesn’t mean that you’ll have the same experience.

In reality, it doesn’t matter if you make other upgrades like stainless steel sleeving of all cylinders and using stainless steel brake lines. With stainless used throughout the system, you can use the time-proven conventional brake fluid and you should never experience rusting or pitting of major parts.

John “Gunner” Gunnell is the automotive books editor at Krause Publications in Iola, Wis., and former editor of Old Cars Weekly and Old Cars Price Guide.

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