Resto-Mod Restorations: Part 10 — Disc Brake Conversions
Many Resto-Mod builders immediately think of installing disc brake conversions on their cars. There are many ways to go about this and there are also many things to consider. In a seminar at Mid America Motorworks, Michael Jonas of Stainless Steel Brakes Corp. said proper brake system choices are dictated by factors like horsepower, driving style, wheel design and tires. Jonas advised that you should look at brakes as a part of your car's suspension system.
Micheal Jonas of Stainless Steel Brakes Corp. says modern disc brakes with aluminum calipers lighten up cars at the corners. With 8 lbs. less going up and down at each front wheel, you get improved cornering and handling.
Jonas pointed out that modern disc brake setups with aluminum calipers lightened up cars at the corners. They have about 8 lbs. less weight going up and down at each front wheel. This improves cornering and handling. Jonas also stressed that there's a relationship between the powerful crate engines used in many Resto-Mods and the type of brakes needed to adequately stop the car.
|Comparing Drum Brakes and Disc Brakes
||Drum Brake Disadvantages
|Cheaper to make
Work best with cable-type emergency brake
More economical to fix
Fit traditional hot rod image
Finned aluminum drums look cool
Don't show as much brake dust
|More susceptible to elements
Heat cause fade
Less effective when wet
Hydraulic cylinders corrode
Heavy (many are cast iron)
Replacement drums hard to find/costly
|Disc Brakes Advantages
||Disc Brake Disadvantages
|Stop vehicle better and faster
Dissipate heat and water better
Better fade resistance
Ligher and more compact
Easier to service and repair
Incorporate lining wear alerts
|Cast iron rotors are prone to rust
Rotors can crack and/or split
Often vibrate or warp
Floating caliper can stick or pull
Pad material builds up on rotor
Enthusiasts doing disc brake conversions have choices when it comes to sourcing. If the car has Mustang II, Camaro, Nova or Granada underpinnings, cheap parts can be found in a junkyard. Brand new reproductions of some of these are also available. "A lot of companies are re-popping them," says Alan Mayes, the editor of Old Skol Rodz. "Bob Drake, Mac's and others are re-popping old stuff and it's nice because you don't have to worry about things, such as whether the spindles were heated up and straightened." In addition, some Resto-Mods are being built on turnkey frames that use specific brake packages.
According to Brent Vandervort of Fatman Fabrications, his firm doesn't manufacture brakes, but does sell adaptors, dropped spindles and packages featuring Baer, Wilwood, Bugzys and Ford SVO packages. Former NASCAR driver Rich Bickle builds Resto-Mod frames at his Muscle Up Performance & Hot Rod Shop with brake packages based on Wilwood Dynalite 6-piston systems.
Muscle Up Performance & Hot Rod Shop uses this cutaway Mustang to demonstrate the Baer disc brake system used on the ready-to-go Resto-Mod chassis its sells.
On his Resto-Mod Camaro, Jeff Noll went for the "big wheel" look. He used V40 straight five-spoke two-piece aluminum rims that he purchased from Vintage Wheel Works. Up front Jeff mounted 17 x 7-in. wheels with 3-3/4 in. backspacing and P225/45R17 Goodyear F1 tires. On the rear he used 17 x 9-in. wheels with 5-1/2-in. backspacing and P255/45R17 Goodyear F1s. In his seminar, Michael Jonas pointed out that wheel size dictates what size brakes to use.
Jeff Noll stuck with the stock '67 Camaro drum brakes on the rear of his Resto-Mod. He uses 17 x 9-in. wheels with 5-1/2-in. backspacing and P255/45R17 Goodyear F1s raised white letter tires.
Early Camaros (except Z/28s) originally came with 14in. wheels. Disc brakes were a factory option. There was also a rare RPO JL8 four-wheel disc option that required 15-in. wheels. When you run taller 16- or 17-in. rims on a Resto-Mod Camaro like Jeff did, you can use any of these or factory disc brakes from Gen 4 Camaros or even C4 and C5 Corvettes. To upgrade even further, you can purchase "big brake" systems from any number of aftermarket suppliers.
Jonas explained that whatever system you use, it is important to have the right combination of wheels, brake rotors, pads and tires. He believes that there is no such thing as too much horsepower or too much brake, but that it's a question of having the right balance of all factors for the type of driving that you plan to do. Wheel prices go up fast, according to Jonas, so it's wise to pick the kind of calipers you want before you buy the wheels. His advice is to get the best brakes you can afford that fit your driving style. Whether they come from a stock factory system or one of the more exotic kits, the needed parts will be the same.
Camaro Conversion Parts
Some of the items you need to buy for a conversion are spindles, saddles, mounting brackets, calipers, brake pads, hubs, wheel bearings, rotors, a master cylinder, brake tubing, brake line fittings, brake hoses, a proportioning valve, nuts, bolts, studs and hardware and power brake parts if you want to have power assist. You'll also need to borrow, rent or buy brake tube bending pliers or a bending/forming tool, plus a tool that puts double flares at the end of brake lines.
Jeff uses 17 x 7-in. front wheels with 3-3/4 in. backspacing and P225/45R17 Goodyear F1 tires. If you buy a quality disc brake conversion kit), the manufacturer can tell you if the rotors and calipers fit your favorite wheels.
If you are buying a high-quality conversion kit (the only kind to get), the manufacturer will be able to tell you if its rotors and calipers will fit the wheels you'd like to use on your car. Otherwise, you'll have take some measurements to calculate backspacing. Most stock style brakes kits for GM cars are designed to fit GM rally wheels, which is more or less the standard for conversions. At the time of his seminar, Jonas was getting ready to release an eight-piston caliper that fits in a 15-in. rally wheel. The caliper was CNC machined from billet aluminum and weighed about eight pounds less than a stock caliper, although it had SSBC's trademark stainless steel pistons and other stainless steel parts.
There are also templates available from wheel manufacturers to check whether the wheels you want to use have enough clearance for your calipers. Again, think about your caliper choices. According to Michael Jonas, many builders think that if they have a big crate engine, they need a big caliper. "Caliper design is like engine design, because the outer size doesn't tell the whole story," he said. "If you've got tiny little pistons inside the caliper, you get tiny brake power even if the caliper is big, but if you've got bigger pistons inside the same sized caliper, you've got bigger brake power." Piston size counts a lot.
Safely support the car with the wheels and tires off the ground and remove those items. Remove the wheel bearing and take off the spindle. Use a container to catch the brake fluid when you undo the hoses. Bend over tabs may have to be straightened with a hammer and punch. Use a flare wrench when undoing the brake line connections so you don't ruin the brass fittings.
During an install like Jeff's, you may may have to straighten bend over tabs with a hammer and punch. Use a six-point flare wrench when undoing and tightening brake line connections so you don't ruin the soft brass fittings.
Some disc brake conversions require you to get drum brake hubs. These mount on bearings that may need to be repacked or replaced. If you're using factory parts in your conversion, you might want to purty things up with some Eastwood brake paint, which is heat-resistant. If you're buying name brand new parts they probably come with a nice powder coated finish these days.
While aftermarket kits can be expensive, a lot goes into making them look better, perform better and last better than the old factory parts. Michael Jonas answered a man who told him that an expert on TV had said that cross-drilled rotors weren't as good as slotted rotors. Jonas said that he guaranteed that any cheap rotor would crack, but that his own cross-drilled rotor, with its improved metallurgy, actually has better durability than a slotted one. He said that a good rotor will last the life of a car if it's properly maintained and added that the way to maintain rotors is to change the pads before worn pads damage the rotor.
Jonas said that anyone can spot higher-quality brake rotors because they are shinier than low-grade rotors. The shininess in the better rotors comes from the fact that they are made of metal with more chromium and more high-carbon steel in it. Lower end rotors will look dull or black. He said that all rotors being manufactured today are made in China, so you can't determine quality by the printing on the parts box that tells you the brake rotor's country of origin.
Disc brake conversion kits will usually include spacers and other parts that help you make the parts fit together just right. It is always good practice to start with a trial assembly before moving to your final installation. On the final go through you should use Loctite on the fasteners and torque everything down properly. Instructions with the kit may provide torque readings or you can look up standard U.S. Army torque specs in auto repair manuals or on the Internet.
When your install is finished, don't go blasting out of the garage with the pedal to the metal. First you should test to see how the new system works. Remember it wasn't put together by a team of highly-trained engineers at an automaker's technical center. All kinds of difficulties can arise when you're teaming up different master cylinders, calipers and pistons, rotors, brake lines, proportioning valves, types of pads and power brake system components.
Adding Power Assist
For his Camaro build, Jeff Noll went with an aftermarket single piston disc brake set up for the front and used a stock '67 Camaro drum brake design at the rear. He replaced the brake reservoir with a Classic Performance Products unit. CCP highly recommends the use of a Corvette dual-chamber master cylinder and a vacuum powered brake booster with all disc brake conversions.
Jeff swapped his OEM brake reservoir for a Classic Performance Products unit. CCP highly recommends the use of a Corvette dual-chamber master cylinder and a vacuum powered brake booster with all its disc brake conversions.
The front part of the power booster is separated from the rear half of the unit by a diaphragm. When the engine produces 16-23 in.-lbs. of vacuum it creates equal pressure on both sides of the diaphragm. When the brake pedal is pressed, a poppet valve shuts and vacuum draws the diaphragm forward, building up about 1100 psi in the brake lines. So you get a dual master cylinder, a larger-capacity brake fluid reservoir and vacuum-generated power assist.
A brake line conversion kit is also available to change the old single-circuit system into a dual-circuit system. These components can be purchased individually or as a complete kit, and you can even order the parts with polished, chrome-plated or powder coated finishes to further dress up the looks of the car.
GTO Disc Brake Kits
Jim Mokwa also added disc brakes to his 1969 GTO. Such kits may include all-new rotors, backing plates, spindles, calipers and pads, caliper brackets, a nine- or 11-in. Delco style brake booster with master pin and clevis, a master cylinder, brass discs, drum valves, brackets, master cylinder lines, brake hoses, banjo bolts, crush washers, wheel bearings, seals and dust caps, all the miscellaneous hardware and complete installation instructions for about $675.
Available upgrades including cross-drilled and slotted rotors, stainless steel braided flex hoses, a complete disc brake conversion hard line sets in stainless steel or OEM tin steel, a brake proportioning valve for four-wheel discs, brake hoses and frame mounting brackets can add another $400 to the cost.
Jim Mokwa added a Baer stainless 11-inch disc brake package with cross-drilled and slotted rotors to his 1969 GTO convertible. The use of last-forever stainless steel brake lines is also a good idea.
Jim installed top-of-the-line Baer four-wheel disc brakes on his GTO. He bought them through Year One, a big supplier of muscle car parts. He feels that their added safety helps protect the money he invested in his GTO Resto-Mod.
Jim installed Baer four wheel disc brakes on his GTO. He bought them through Year One, a big supplier of muscle car parts. He used 11-in. diameter slotted and cross drilled four-piston calipers in the front of the car. At the rear are 11-in. slotted and cross drilled two-piston calipers. According to Jim, the Baer Brakes were very expensive, but came in a kit that bolted on very easily.
With the silver-finished Baer two-piston calipers showing through the five-spoke Torq Thrust II wheels at all four corners, the car has a very cool look.
Jim feels that a four wheel disc brake set up is something that all builders of high horsepower cars should install. Not necessarily the Baer brand, however, because there are many suppliers of kits that are much more affordable. "Just think of all the time and money you put into your car and if you can't stop quickly to avoid an accident, it's all wasted," says Mokwa. "My advice to Resto-Mod builders is simple-don't cut any corners when it comes to installing brakes!"
Many 1960s GM shop manuals recommend either Delco Supreme No. 11 or DOT-3 hydraulic brake fluid or the equivalent. When Michael Jonas gave his seminar on brakes, he said that if he uses DOT-3 in cars he stores at his home in Buffalo, N.Y., it causes problems because DOT-3 absorbs water. "If you play with DOT-3 it will make your fingers look like prunes," he joked. "When DOT-3 turns brown, you have to chuck it; I used to be an SCCA tech inspector and the first thing I had to understand is that it turns brown when it absorbs water and dirt."
Jonas prefers the latest high-temp DOT-4 fluid because it absorbs low amounts of moisture and takes high heat. DOT-4 is not silicone-based like DOT-5.0 or 5.1. Most auto parts stores carry DOT-3 or High-Temp DOT-3, but what you need in a Resto-Mod is High-Temp DOT-4. NAPA stores usually carry it.
If your system currently has DOT-3 fluid, you can use a siphon to suck it out of the master cylinder and pour in the Dot-4. Crack the bleeder screws until all the DOT-3 flows out. Naturally, you should use nothing other than brake fluid. Some folks think alcohol will clean a system, but it blows seals up like balloons.
Jonas doesn't like DOT-5 (silicone) brake fluid for anything other than normal daily driving. He warned that if you drive your Resto-Mod fast and your DOT-5 fluid warms up, your pedal will be really hard one minute and go right to the floor the next. When silicone brake fluid fails you want it to not be in your car.
No Rust Resto-Mod Brakes
Few enthusiasts drive their Resto-Mods all year round and seasonal storage of a vintage vehicle can cause rust to form in the brake lines, especially when moisture-absorbing DOT-3 brake fluid is in the system One way to avoid this is having the piston bores in rear wheel cylinders and master cylinders lined with stainless steel or brass. Brake and Equipment Warehouse in Minneapolis and White Post Restorations in White Post, Virginia are two good sources of relining services and parts. Switching to last-forever stainless steel brake lines such as those available from Classic Tube and Inline Tube is also a good idea.
New Ideas in Disc Braking
There are many brands and styles of brakes offered today and Michael Jonas covered them in his seminar. He pointed to a Tri-Power caliper and described it as a "Corvette C5 caliper on steroids." Engineers took a two-caliper piston, spilt it apart and put a third one in the middle. It is a new brake concept.
Another caliper that Jonas displayed had slots on the two inner pistons. Brake pistons are usually flat topped. He said the slotted design evolved out of NASCAR racing, where air circulation to brake parts is critical. Heat is a natural enemy of brakes. Cross holes or slots allow airflow through the calipers and improve heat transfer, as do slots in the pistons. They make them more durable.
With the silver-finished Baer two-piston calipers showing through the five-spoke Torq Thrust II wheels at all four corners, the car has a very cool look.
Jonas showed off his latest rotor designs with what he said were strategically located slots sliced smooth. He said the slots are like windshield wipers for pads, cleaning them so they last longer. He explained that pads are not made of solid material. They are actually made of material that's like a sponge. Jonas said that glazing or pulsation means that the pad has become full of material and hardened up so that it then generates too much heat.
Heat isn't generated by brake rotors; it is generated by the brake pads hitting against the rotors. If you ride your brakes or switch to a more aggressive type of pad, you'll increase braking system heat. Some slotted rotors are "directional" so that the airflow through them cools better. If they are mounted on the wrong side of the car, they'll cool less, but won't create any big problems. Some newer rotor designs have staggered vanes. If you hold them up, you won't be able to look through them. This new technology creates a larger mass for air to whip through at higher velocity, so that it does a better job of cooling.
Jonas says that he considers his slotted rotors to be best for everyday driving, but that when you get into cars with "open" wheel designs, the cross-drilled rotors are popular with enthusiasts because they can then see their aggressive-looking appearance. Both types work equally well in testing, but if you have an open wheel, the cross-drilled rotors win extra points for their beauty.
Jonas pointed out that some braking problems like brake fade and locking up the brakes have nothing to do with calipers, rotors or pads. Brakes suffer fading when the brake fluid is actually boiling. That means the fluid is compressing and the rotors will not deal with the heat, so it is transferred to the calipers. Jonas said that too avoid fade you have to have the right wheels, right brakes and right pads and "dial in" the whole braking system just right.
If the brakes on the car lock up, it actually means that the tires have lost their grip and the brakes are working more than the tires to stop the car. Tests that were done in conjunction with companies like Goodyear Tire and Ford—plus 35 years of autocrossing a Corvette—taught Jonas how all this stuff works.
Jonas's biggest warning boils down to the idea that a Resto-Mod builder shouldn't use a car he saw at a show to base his brake system choices on. "You're buddy's big wheels may not work on your car," he warns. "If you go to bigger wheels on your car, you have to give up ride quality for handling."
Jonas said Stainless Steel Brakes Corporation manufactures calipers, rotors, cables, master cylinders and more. "We do whole braking systems, as well as the individual pieces," says Jonas. "Some re-pops are terrible in quality, so we build our own stuff and have two quality control inspectors watching everything. You have to have good quality, because lots of stuff advertised as easy-to-install is not a direct bolt on like ours."