Wilwood calipers offer more rigid design, better brake pad distribution
After swapping a Chevelle’s factory front discs with aftermarket spindles and 12-inch rotors derived from an early ’90s Camaro with the 1LE option, we benefitted from improved handling and shortened stopping distances. But we felt we were still leaving something on the table, and not taking full advantage of the increased rotor diameter.
The aftermarket spindles retained the Chevelle’s original cast-iron D52 brake calipers, which are adequate in most situations and have been deployed in countless GM applications since 1969. To their credit, they are rock-solid reliable, and in the unlikely event of failure, are an inexpensive, easy-to-replace, parts-store item. But optimum performance has never been the goal of any OEM design, especially when the bean counters get involved. Our goal now was to further improve the Chevelle’s brake performance.
A bit of online research turned up Wilwood’s two-piston, billet aluminum, bolt-on D52 replacements. There are several benefits to consider with the Wilwoods, not the least of which is more evenly distributed brake pad clamping for improved stopping power. They are compatible with original rotors and brake pads, offer a more rigid design to reduce caliper flex, are significantly lighter (reducing unsprung weight), and will clear most 15-inch wheels — and even 14-inchers in some cases. Generally, if the wheels fit the OE D52 caliper, they will clear the Wilwoods, too
Serious hot rodders love vintage speed and high-performance equipment. When you look at the “wish lists” of nostalgia rodders, you’ll find exotic parts like real “block letter” Edelbrock finned heads, Harman and Collins magnetos, Auburn dash panels, and arguably the most elusive item of all, the legendary Kinmont Safe Stop Disc Brake.
What were Kinmont brakes? Old car aficionados may recall Kinmonts as an interesting side note on two notorious, postwar, would-be auto manufacturers: the flamboyant Preston Tucker and the enigmatic Gary Davis, originators and self-promoters respectively, of the ill-fated ’48 Tucker Torpedo and the hapless Davis three-wheeler of the same era. Tucker’s short-lived enterprise (only 51 cars were produced) ended up in the courts, but after an ill-deserved trial for stock fraud, he was acquitted of any wrongdoing. Davis, also indicted for fraud, after producing 17 prototypes (additional cars were built later from stockpiled parts), served 18 months at a misdemeanor farm in Castaic, California.
Both men’s efforts had something else in common, besides trials and tribulations. Tucker and Davis allegedly wanted their radical new models to be equipped with the best stoppers of the day, so they turned to a small manufacturing company in Los Angeles for a rather unusual disc brake that did not rely on a rotor/caliper assembly to function effectively. Attributed to an inventor, Joseph M. Milan, and originally called the Milan brake, they became better known by the name of the company that tried and failed to make them a success, as Kinmont Safe Stop Disc Brakes.
Period articles on both the late ’40s-era Tucker and Davis refer to disc brakes, and vintage cutaway drawings of both Tucker and Davis cars clearly show the distinctive Milan/Kinmont finned backing plates. We know that prototypes of both makes experimented with Kinmonts, but neither car employed them in its limited production models, due to their relatively high cost (versus conventional hydraulics) and the lack of time the engineers in both companies had for extended in-service testing.
Years ago, the late-Gary Davis told Special-Interest Autos’ Mike Lamm that he’d tested Kinmonts, but “didn’t have enough money to get one (tooled) in aluminum. So I used cast iron, and this made the load too heavy below the center of gravity.
We’ve learned even more, and since I’ve been running a set of Kinmonts for 11 years on all four wheels of my ’32 Ford roadster, I’m in the unique position to bring you up to date.
History Joseph M. Milan, an exotic car mechanic, recorded the first of his 10 disc brake patents back in 1936. Allegedly, the basic design was patterned after a clutch-like brake assembly used on mobile World War I German heavy artillery pieces. Relentless researcher Fitzhugh traced the first competition use of the Milan-style brake to a 1941 Indy 500 race car owned by Joe Lencki and driven that year by Emil Andres.
This first racing Milan brake was made entirely of aluminum. It consisted of a cast aluminum cover (more popularly called a “hat”), with 12 forward-facing vents that were angled to scoop in cooling air, and direct it across a 360-degree continuous ring, circular flat braking surface. The braking material, a soft asbestos compound with brass rivets, made by the Raybestos Corporation, was attached in three places to the brake cover (also known as a driving member), which rotated with the wheel.
The friction material was squeezed between a stationary backing plate and a pressure plate that resembled a conventional automotive clutch. Four simple spring straps return the plate to the “at rest” position. The simple adjustment consisted of just two nuts that regulated the clearance between the pressure plate and the backing plate, which was distinctively and efficiently finned to dissipate heat buildup. Unfortunately, Andres’ Kennedy Tank Special crashed on Lap Five in the 1941 Indy 500, and finished an ignominious 30th. But alert “railbirds” like Preston Tucker saw these newfangled brakes and would consider them seriously once hostilities ceased and racing began again five years later.
Fast forward to the Kinmont Manufacturing Company in Maywood, a suburb of Los Angeles. Kinmont produced hydraulic dredging equipment. During World War II they manufactured a torpedo launching platform and built a prototype U.S. Army tank. Before the war, Milan, along with a group of investors, spent a great deal of money prototyping his novel brake design. He had been looking for a company to manufacture and market the brakes in volume.
Coincidentally, Bill and Ralph Kinmont, heirs of the Kinmont Company’s founding brothers, were seeking postwar manufacturing opportunities. Bill Kinmont, a racing enthusiast, met Joseph Milan some time earlier, and had seen his brake design. Hoping to develop a practical brake for the road, the Kinmonts retained Milan as a consultant, and began manufacturing what would soon become known as Kinmont disc brakes.
The next instalment in our Hot Rodding 101 series is all about Brakes! Matt sits down to cover the many options for stopping power for your Early Ford Hot Rod. We are only covering the brakes that we would use on our earlier style build, as disk brakes started to become popular in the late 60s. This is in no way the end all list for brakes, we just covered the ones we typically used and see! There’s a bunch of other options we didn’t cover, let us know in the comments below what you like you use on your traditional hot rod!!
Since the juice brakes were updated not long after I got the car, one of the previous owners had changed the standard Model A mechanical brakes to hydraulic (juice) brakes. They had used the earlier brakes and I converted to the later 39-48 version which in my experience are easier to maintain. The reason for taking a look at the front brakes was that the passenger side front was grabbing a little when cold.
All the the shoes were cleaned up with abrasive paper, the shoe touch points and adjusters lubricated. The drivers side front brake drum is showing signs of wear from previous brake shoe wear issues. A new drum will be sourced as well as a set of shoes. After the inspection the drums were refitted, wheel bearings repacked and the brakes adjusted. Wheels were then refitted ensuring that the wheel protection rings were fitted between the wheels and brake drums. These rings stop the wire wheels from cracking. Wheel bearings were adjusted and split pins fitted, then brakes were adjusted.
Whilst working on the front brakes I took the opportunity to adjust the cables on the excellent Cling handbrake system. Details here
The relationship we have with our classic cars tends to be a love/hate affair. We love the styling and the nostalgia of cool American iron from more than a half-century ago. However, suspension and braking systems are below par when you consider what’s sitting on showroom floors today. Drum brakes have their place, and obviously this arrangement is appropriate on a concours-restored show car where originality and show judging are paramount. However, if you drive your classic on a regular basis, maximizing your own safety and the safety of others depends upon getting your braking system up to date.
There was a time when you had to rummage through salvage yards to find a suitable disc brake package. These days, there’s a wealth of new disc brake kits for a wide variety of classic cars, from the Model T all the way up through the cars of the mid-20th century. Your decision should be based on what meets your personal needs and tastes. If your classic ride is a completely stock example, all you need are OEM-style front disc brakes, a dual-circuit master cylinder, new brake lines, and rear drum brakes.
Drum brakes have long been the mainstay of automotive braking systems. They perform quite well in rear axle positions yet are prone to fade when they get hot. When they get wet, friction is compromised and drum brakes can become unsafe. They also tend to lock up during hard braking.
If you have a performance-oriented model, or you’d just like a measure of braking performance beyond what the factory offered, the aftermarket may be able to assist. You may be surprised by the breadth of applications covered today, for both front and rear disc brakes.
Particularly important is the decision to convert your single-circuit hydraulic braking system to a dual system, meaning two separate circuits for the hydraulics fore and aft. American cars had single-circuit hydraulic braking systems prior to the 1967 model year, when dual braking systems became federally mandated. A dual-circuit braking system includes a two-chamber master cylinder, split between front and rear systems. The purpose of this is to maintain partial braking should there be a hydraulic system failure somewhere —a single leak should then affect only one circuit, not both as it does with a single-type system. In factory dual-circuit systems there is usually a pressure differential valve of some sort and a warning light to let you know you’ve lost either system. The pressure differential valve used on many vehicles has an internal “shuttle” valve that must be recentered once the trouble is corrected to turn the warning light out and enable proper bleeding of the system.
The humble drum brake is little more than C-shaped shoes/linings within a rotating drum. Because the front brakes do most of the work, the rear drums are there more as a backup for the fronts
Why opt for disc brakes? Drum brakes are prone to fading under hard use and, when wet, will often become seriously compromised. Disc brakes, on the other hand, are very effective stoppers.
They provide excellent braking force but are also more effective at dissipating heat, enabling them to endure severe use with good resistance to brake fade —the compromise in friction that occurs when the braking components become overheated. Even a front disc/rear drum system, with the split circuitry of a dual system, can offer a substantial improvement in braking performance and safety.
Most mainstream classic cars need little more than these cast-iron caliper, OEM-style disc brakes, and having them only in the front is usually a sufficient upgrade for normal driving. This is a Kelsey-Hayes four-piston front disc brake on a classic Mustang.
When you’re considering a disc brake upgrade, first determine if your car was ever available with disc brakes; if you determine it was not, investigate further to see if a system from a later version of your model offered discs. For example, a 1963 Plymouth was not offered with front disc brakes, but the parts from the right 1973 Plymouth could be adapted.
Of course, the aftermarket can simplify that process by providing whatever you might need for a disc conversion in kit form, eliminating the need to search out vintage parts from a salvage yard and the guesswork that can be involved in attempting to merge those items with your car. If you go this route, bear in mind that brake pad friction materials should be chosen based on the kind of driving you’re going to do. The daily commute or weekend getaway doesn’t call for hard friction materials designed for racing.
For a long time, six-cylinder Falcon, Comet, and Mustang owners couldn’t get front disc brakes. Only V-8 cars were available with them, and those models used five-lug wheels as opposed to the four-lug hubs found on six-cylinder models. However, given the intense demand in more recent years from six-cylinder owners, aftermarket companies answered the call with disc brake conversions for the inline-powered models. This example from SSBC-USA is a simple bolt-on kit you can install in a day.
BRAKE FRICTION MATERIALS
Some years ago, asbestos was commonly used in brake shoes and pads, but when the health risks became clear, the material was phased out. When working on a vintage car, use caution with unknown friction materials —the brake shoes on a 50-year-old car may well be old enough to contain asbestos.
These days, we have three basic types of brake friction materials: Non-asbestos organic, semi-metallic, or ceramic for high-performance driving. Non-asbestos organic compounds are the most common type of brake friction material and are made from bonded organic fibers that retain shape by a resin or glue. Organic brake linings are made from a combination of several proven plant-derived fibers. Non-asbestos linings have a small amount of metallic content in them, typically brass to dissipate heat while contributing to abrasiveness (friction) for better stopping.
Affordable OEM-style disc brake kits are available for Ford, GM, Chrysler, and AMC classics from SSBC-USA (pictured here), CPP, Brake Performance, and LEED Brakes. They yield a factory-original appearance and will improve braking performance.
As the dominant choice for both front and rear brake systems for the last quarter-century, disc brakes offer a number of advantages over drums, including better serviceability. Without having to deal with return springs and adjustment wheels, a nice clean disc brake rotor and pad replacement should take about half the time a drum brake service requires.
But that’s not to say disc brake service doesn’t benefit from taking your time and paying attention to the details as you go along. Sure, you could breeze through and be back on the road in no time, but with a little bit of forethought you can get the best performance from your new brakes, avoid extensive damage, and make your next brake replacement go much smoother.
We followed along as tech columnist Jim O’Clair got his hands dirty replacing the brakes on a late-model Subaru and pointed out various tips, tricks, and other good advice for servicing pretty much any vehicle with disc brakes.
Hang The Caliper
While you should always inspect the brake hoses and the calipers when taking apart the disc brakes for service, it’s not always necessary to replace the hoses and calipers.
In those instances when you’re replacing just the rotors and pads, make sure to hang the caliper up and away from your workspace rather than just let it dangle by the hose. Brake hoses aren’t meant to be kinked or stretched, and dangling the caliper can do both, leading to damage
.While you could easily buy a caliper hanger set or devise a caliper hanger from zip ties, rope, or an old cloth, Jim fashioned one from a length of chain and a couple of hardware store S-hooks that he had laying around to make an easily adjustable, simple to use hanger. Make sure to hang the caliper from something sturdy and not from a brake line, hose, or fender liner.
In everyday driving, you probably think about bleeding your car’s brakes about as often as you wonder whether you’ve adequately arranged your sock drawer. Even though you ultimately place a great deal of faith in brake fluid to do its job without fail day in and day out, it routinely goes overlooked even during normal maintenance.
On the other hand, you’ve probably driven a car with a soft brake pedal or a pedal that dropped straight to the floorboard and suddenly found yourself unable to think of anything but brake fluid, as the stop sign and the brake lights ahead of you grew increasingly close increasingly fast.
It typically happens about half of the way home when picking up a new project vehicle, and leads you to wonder why you even dared to think you could fix up that rusty heap, a car that probably reached that state of dilapidation long after somebody else stopped thinking about its brake fluid altogether.Indeed, brake fluid bleeding is far from the sexiest task.
It doesn’t add horsepower, it doesn’t make the car any more attractive, and the best result you can hope for is that the car will stop as it was designed to, no better. On the other hand, just like insuring your car, it’s a necessary task. It’s also less of a convoluted or labor-intensive task than many people fear it to be.
1. Need To Bleed?
A spongy or ineffective brake pedal is usually the first indicator that something’s wrong with your brake system, and the causes behind that one symptom can range from rusted brake lines, to cracked flexible brake lines, to worn cylinders or seals in the calipers or wheel cylinders. Generally, you can count on finding some part of the normally sealed brake system admitting air, which compresses while fluid doesn’t. So bleeding – or flushing the brake fluid system – is necessary to get out all of that trapped air, but it’s also something that should be done on a regular basis to replace degraded fluid with reduced effectiveness. Your car’s user manual likely recommends bleeding every two to three years.
Nice evening so I thought I’d test build the front brakes before fitting in July. No wheel cylinders as I’m hoping to use the relatively new ones that are on the existing back plates. It was a useful exercise and gave me some assurance that I’ve got all the bits to fit them in anger. The shoes are the nice Bob Drake type from Miles at Jack hammer. One downside was that when I took the shoes out of the box there was a dent in a couple of the shoes. Not the end of the world, but a little miffed all the same. Now waiting for Miles to get his next order from Bob Drake so I can build up the rears at least a little. Won’t be able to do too much as I need to reuse the existing handbrake levers.
Whilst I’ve gone as far as I can on the oil pan until the next parts delivery I thought I’d do a little bit of work on the excellent set of backing plates I purchased from the States. The adjusters were a little rusted and stuck so a little freeing up was in order.
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