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In the lastcouple of issues, we devoted space to brake system tech tips. Some of those tips are performance related, while others are maintenance related. In any case, all of them are important. We’ll continue our look at brake system tech tips with this issue. Check them out and keep your eyes peeled for more tips down the road (as in next week’s issue!).
If you have a vintage car or truck that hasn’t been serviced in an eternity, flush the brake fluid! Years (decades?) of rust, scale and other crud actually collect in the brake lines. This junk stops the brake system from working to its design potential. The easiest way to flush brake lines is to open up the bleeder screws, push the pedal a few times and let Mother Nature do the work. Keep the brake reservoir full with fresh fluid (DOT 3 or better). Repeat the process until the expelled fluid is clean. You can expect to go through several cans of fresh fluid during the process, but in the end, it’s definitely cheap insurance.
When you try to crack open a common brass fitting used on an old brake line, it might not be such a good idea to use a flare nut wrench. Why not? That’s what they’re designed for, isn’t it? Simple: Flare nut wrenches are sometimes thin on the ends so they can fit tight spots. Because of this, they often flex when you really lean on them in an attempt to crack open a frozen fitting. Believe it or not, we usually use a tight fitting combination wrench to start the process, and then make the switch to a flare wrench. It saves rounding the tops off the flare nuts.
When bleeding brakes on a car equipped with a balance bar and a pair of master cylinders, try bleeding one caliper on the front and one on the rear simultaneously. This helps to eliminate balance bar binding.
When installing rear drum brakes, check the self-adjuster to ensure that it rotates freely. If not, clean the threads and apply a small amount of anti-seize compound to the threads.
When the time comes to custom plumb brake lines in a car, don’t cheap out on the line. Sure, corner parts store “rediflex” lines are available, but they’re really a band-aid fix. Instead, think about the stuff at the top of the heap: 3/16-inch O.D., 0.028-inch wall stainless steel tubing. Stainless steel is tough, doesn’t deteriorate easily and, yes, isn’t that easy to work with. The solution is to use the right tools. We’ve had very good success using a dedicated 3/16-inch Imperial Eastman tubing bender and a Rigid mini-tubing cutter along with a heavy duty Rigid 37-degree flaring tool. Be sure to use tools designed to handle stainless. They’re stronger than run-of-the-mill plumbing tools, simply because stainless is more difficult to work with. Why use 37-degree fittings? Well, it’s tough (if not impossible) to double flare stainless tubing. We use 37-degree fittings in conjunction with A-N tube nuts and flares available from Aeroquip, Earls or Russell. This way, you get a leak free aircraft-quality fitting end that doesn’t mandate a double flare.
Tip 30 – CONTACT! The contact points on drum brake backing plates can become grooved with use. No problem - just get some new backing plates. Unfortunately, if you have a rare car (or if you’re working with vintage hardware, which is extremely popular today), finding replacement parts might be easier said than done. If your backing plates fall into that category, try this: Weld new metal into the grooves (a MIG welder works perfectly). Grind down the weld until it’s smooth, and you’re ready for action. You might be surprised at how much more effective those old brakes have become.
Tip 31 – PONY EXPRESS: Plenty of early Mustangs and other Ford products were equipped with 9-inch diameter rear brake drums. They’re small because the cars were light. To add a wee bit more stopping power, think about swapping in the drums, backing plates and other hardware from a Fairmont wagon. It’s an easy swap using stock OEM components.
Tip 32 – WEIGHT WATCHERS: Big bad Buick finned aluminum brake drums are all the rage with street rodders today. Those brakes not only look good, they also offer impressive stopping power (for a drum system). There are some other inexpensive, easier to find aluminum drums out there, particularly if you have a GM vehicle with a rear axle that has common 5 lug on a 4-3/4-inch-diameter bolt circle along with back drums that measure 9.5-inches in diameter by 2-inches wide (that is just about every vintage GM compact or mid-size car). You can drop 10 pounds of unsprung weight by removing the existing 14-pound cast-iron drums and installing a pair of aluminum drums, which weigh 9 pounds each, including their iron liners. Where do you find these aluminum drums? Try looking under the following candidates in your local wrecking yard (FYI, not all of these vehicles came with aluminum drums – as near as we can tell, they were packaged according to option groups on a specific automobile or light pickup):
• Blazer/Jimmy, '83-84, S or T models
• Buick, '80-84 Le Sabre, '85 RWD, '78-81 Century, '78-87 Regal
• Riviera, '81-85
• Camaro, '82-92
• Chevy passenger, '86-89
• Cutlass, '78-82
• Firebird, '82-92
• Grand Prix, '78-85
• LeMans, '78-81
• Malibu, '78-81
• Monte Carlo, '78-81
• Olds Delta 88, '80-85
• Pontiac, '80-81, '83-85 Bonneville, '86 Parisienne
• S10/S15, '82-84
• GMC Sprint/ El Camino, '78-81
Peak brake fluid temperatures should never exceed 240 degrees centigrade (that’s a whopping 464 degrees Fahrenheit) or operate over 200 degrees centigrade (392 degrees F) for more than one hour. If that occurs, expect to change plenty of pieces in the system (not the least of which are seals). FYI, that’s why some road racers use brake fluid cooling devices.
Tip 34 – BRAKE BIND: If you have a car in which, after a bit of use, the pedal becomes hard and the front brakes drag, take a close look at the pushrod (between the pedal and the master cylinder or booster). If the pushrod is not adjusted properly, brake fluid will not be allowed to return to the master cylinder freely. As the car is driven, these components tend to heat up and the clearance (if there is any) changes while the various bits expand. The end result is a pair of brakes that usually refuse to release correctly until things cool down.
Tip 35 – SEAL DEAL: Never, ever clean a master cylinder with carburetor cleaner. Carb cleaner can quickly kill the seals in a master cylinder. Bottom line: It’s not brake system safe.
When making a swap from drums to disc brakes, be certain to use high temperature grease on the front wheel bearings. What’s the big deal about it? Simple: Disc bakes can generate a bunch more heat than good old-fashioned drums. The end result, of course, is more heat is transferred to the wheel bearings and, consequently, an increased need for a high temperature lubricant.
