GM midsize cars have become very popular with the muscle car crowd. The powerful Chevelle tops the list for many enthusiasts. These models can be found at the drag strip, on the road course, on the surface streets in Everytown, USA, and at the autocross course.
It wasn ’ triiodothyronine until the adolescence of the muscle car when the inaugural front disk brake option last became available. however, with the independent concenter on big-blocks, transmissions, and gearing, disk brakes remained a rare option and possibly were tied thought of more for the newcomer road-racing series than as a serious component for the strip and avenue bang-up .
One way to do a budget upgrade is to use modern calipers from different models to take advantage of technology without spending a lot of money. This 1969 Camaro was fitted with a set of Z06 C6 Corvette calipers.
In this article, our focus is on a budget-friendly installation of a four-wheel phonograph record brake upgrade on a freshman Chevelle. The test car is a manual-brake, single-reservoir headmaster cylinder car that was fit ( like to all Malibus of the beginning few years ) with drum brakes on each corner. Stock wheels were standard Kelsey-Hayes welded steel 14×5-inch models with a 1-inch outgrowth .
Classic Performance Products (CCP) offers brake upgrades and complete kits for a number of Chevrolet models and applications. The kit we installed was supplied with new rotors, spindles, single-piston calipers, brake hoses and rear lines, brackets, the master cylinder, and booster. Most of the CPP kits for these GM A-Body cars include a choice of booster size from 7, 8, 9, or 11 inches. Drop spindles are an option for those wanting to lower the stance and center of gravity but still maintain full suspension travel. The overall result is improved ride and handling characteristics. Slotted and drilled rotors can also be had for an extra cost. These kits are about as complete as they come.
This ascent consists of a complete kit from classical performance Products ( CPP ) along with the addition of power serve via a vacuum supporter. CPP went through a lot of workplace to assemble all of the want components so an median do-it-yourself would be able to complete the initiation with basic handwriting tools and possibly a little help from a buddy over a weekend .
The kit is based on single-piston calipers that were used on thousands of vehicles from the former 1980s. We will cover these calipers in greater detail under the magnetic disk and caliper sections. For now, it will suffice to explain that these calipers work in junction with 10-inch rotors that fit most 15-inch wheels .
Wheel fitment is a critical retainer when you ’ re upgrading the brakes on your brawn car. Remember, many of these cars from the muscle cable car era were fitted with 14-inch wheels from the factory, therefore bicycle headroom is one of the critical aspects to check anterior to choosing a brake upgrade kit .
This Tech Tip is From the Full Book, MUSCLE CAR BRAKE UPGRADES: HOW TO DESIGN, SELECT, AND INSTALL. For a comprehensive examination guidebook on this stallion capable you can visit this connect :
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BEAT THE DRUMS
Drum brakes have their topographic point but are well suited to the more pedestrian cars of the day, such as a four-banger Chevy II. When you could order a 375-hp 396-ci 4-speed Chevelle with 4.10:1 gears direct from the factory, those lank 9.5-inch drums were hard outmatched. When post modern, the drums worked well for the modal driver. As those enthusiasts lucky enough to have lived through that era will attest, the cars did brake acceptably well considering the rather rock-hard tires of the day .
The secondary (trailing) brake shoe on the left is much longer than the primary brake shoe on the right. The secondary brake shoe provides more of the braking force.
The wonder wasn ’ metric ton if these cars would stop in a becoming distance. The better question was whether they could muster the effort more than once. Freeway antics in today ’ randomness universe can easily create a situation where a panic catch from 70 miles per hour to a stand is promptly followed by acceleration back up to 70 miles per hour that about immediately calls for another dramatic slowdown. If insufficient time has passed to allow the brakes to cool, that second feat might call for some evasive maneuvers in a Chevelle with front drum brakes .
For purists who feel the motivation to retain those brake drum binders, there are not many brake shoe options available as upgrades. The early Chevelles and their A-Body cousins used a 9.5-inch brake drum set in the front with a 2.5-inch-width brake shoe, while the rears were the same diameter but narrower at just 2 inches .
Certain applications of A-Bodies, particularly with El Caminos, have 11-inch drums on the raise to improve braking due to higher expect seam loads. Of course, these demand their own set of shoes because the smaller 9.5-inch drums and shoes will not interchange .
DRUM BRAKE SHOES
A set of four drum brake shoes will come in the box and the inaugural matter any installer must do is separate the shoes into chief and secondary coil versions. If you look close at the shoes, you will notice that the secondary horseshoe uses a slenderly longer length of brake material than its primary collaborator. The basal shoe constantly is installed as the leading shoe : face forward. The secondary brake shoe is constantly located on the trail or rear put .
The cause for this shoe placement is what the diligence referred to as the self-energizing ( servomechanical ) action of most drum brake systems. When the steering wheel cylinder is activated, the pistons push both the basal and secondary shoes outbound .
Looking at the drum system for the leftover front for example, the elementary brake shoe hits the rotating cram and is immediately forced into a counterclockwise motion. The adjustable connect bar at the bottom of the shoe attaches to the secondary coil brake shoe and forces the larger secondary brake shoe into the drum with more wedge. This is why the secondary shoe is fitted with more friction open area .
A common issue that crops up with drum brakes is when the installer fails to realize the shoes are different, ending up with a pair of primaries on one side of the car and a pair of larger secondary shoes on the inverse side. When installed in this faulty fashion, the car will pull hard to the slope with the secondary shoes whenever the brakes are applied. Of course, the best way to avoid this is to install the shoes correctly .
While we ’ re on the subjugate of improving brake drum brake efficiency, high-mileage cars often suffer from grooved backing plates where the shoe slides across the backing home plate during braking. These grooves restrict motion of the shoes, which reduces their effectiveness .
There are backing plates reproduced by Right Stuff Detailing, so replacement parts are available, but you can besides repair original plates by merely MIG welding material into the grooves and then smoothing the weld back to a level coat. It ’ s a brassy animate and not unmanageable if you have access to a MIG welder .
If the plan is to rebuild a drum bracken set, just consider replacing everything, including the drum. complete rebuild kits with all the springs and small parts are calm available through companies such as Raybestos or Wagner, and these normally include the wheel cylinders .
If the car has been sitting and the roulette wheel cylinders are corroded, don ’ deoxythymidine monophosphate try to rebuild the cylinders since they will barely leak past the pit in the cylinder. A small tap of white lithium grease on all brake shoe contact points will help the shoes slide across the back plates .
We won ’ t spend much clock on the two-year-only 1967–1968 Chevelle movement disk brake apparatus. This system resembles the early Corvette and 1967 Camaro phonograph record brakes that used a fix four-piston caliper. While this system worked sanely well, it suffers from a significant invention flaw .
The defect is that hydraulic pistons use arctic seals located on the pistons, sealing to the cast-iron caliper cylinders. These calipers were bolted over 11-inch rotors. After a few years with brake fluid absorbing water like it is prone to do, these four-piston cylinders began to corrode, leaving rust spots that soon allowed brake fluid to leak past .
late brake upgrades fixed the seal into the cylinder bear and sealed against the piston. The pistons broadly are made of a hard material and preceptor ’ t corrode as easily, so the system is less susceptible to leakage. These calipers are however available but require a specific 1967 or 1968 A-Body spindle because this design was carried over in the 1968 model year with the new Chevelle soundbox style. As with many of these calipers, they are specific to the correct or left side because of the hemophiliac screw placement. If the sides are unwittingly swapped, the hemophiliac screw will be on the bottom and of fiddling use for bleeding the brakes .
General Motors switched to a single-piston, floating caliper in 1969. This caliper design became a staple for GM models for decades.
It is possible to apply stainless steel sword sleeves to original factory calipers when doing a restoration. The first company to offer this option commercially was Stainless Steel Brakes, but other companies now besides perform this tax. One company we discovered is called RK Sleeving in Upland, California .
Starting in 1969, General Motors converted to the now-familiar large single-piston, floating caliper that became the standard for decades. The one piston is located on the inboard side and uses a mount that allows the caliper to slide along large metallic pins that pull the outboard motorboat bracken slog into the rotor. As you can guess, there is a quite a spot of submission in this design, which places most of the load on the inboard diggings, so these tend to wear more quickly .
even with this sliding caliper, the arrangement is very full-bodied and retained the 11-inch rotor diameter from the original 1967 four-piston calipers. While many performance brake companies downplay this system, it includes the widely used GM D52-style brake pad. What ’ mho good about this popular brake slog is that fair about every bracken slog company in the world makes a pad for this application, so a lot of choices are available when it comes to pad choice .
SPINDLES, RESERVOIRS, AND BOOSTERS
This system was retained throughout the Chevelle earned run average from 1969 through 1972 and makes an easy conversion for earlier A-Bodies. The spindles don ’ thymine even need to be changed. Later spindles used larger bolts to attach the steer arm that will have to be drilled out with a hand drill or drill press. The magnetic disk brake floating calipers work well angstrom retentive as the cast-iron slides do not become corrode and the big pins remain clean .
For early Chevelles and A-Bodies, this conversion will besides demand dumping the original single-reservoir dominate cylinder and replacing it with a double reservoir, which besides requires some custom-made brake plumb. A standard 1-inch nonpower overcome cylinder for a 1969 Chevelle will bolt in place of a standard nonpower early single-reservoir master cylinder, so that ’ s a no-brainer, although we don ’ t very like the high pedal campaign .
Some enthusiasts think that magnetic disk brakes besides require a might supporter, but this is not wholly truthful. It ’ s possible to use a nonpower overlord with front phonograph record brakes and the only real price is slightly higher pedal effort .
My experience with early on Chevelles revealed that using a 7/8- or 15/16-inch-diameter piston master cylinder dramatically increases the line press to the front calipers and besides to the spinal column brake. This reduces pedal feat but besides increases pedal travel to make up for the lose volume using the smaller master cylinder piston .
To some people, this extra pedal travel can make the pedal spirit bathetic when in reality it is just extra locomotion necessary to move the fluid. While a little point, it is noticeable and some may find it objectionable. For everyone else, you become acclimatize pretty promptly .
The size of the master cylinder piston has a direct effect on the amount of pressure created by the effort placed on the brake pedal. A smaller piston creates more pressure with the same pedal effort than a larger piston does. (Photo Courtesy Wilwood Engineering Inc.)
The physics behind this affect is simple : a smaller dominate cylinder piston creates more atmospheric pressure with the same sum of pedal attempt. How much is this deserving ? We ’ ll spare you the mathematics and barely give you the numbers : With a typical 75-pound load applied to the brake pedal with a 6:1 pedal point proportion, this applies 450 pounds of force on the master cylinder. A 1-inch master will generate 573 pounds per square inch of brake line pressure, while a 7/8-inch master cylinder piston will bump that pressure up to 748 psi, a 30-percent addition in occupation pressure. You will notice that immediately .
conversely, adding a larger 11/8-inch master using the same pedal point forces as above will reduce the line pressure from 573 psi to 454 psi, which is a 20-percent decrease or drop in note coerce. That means you will have to step on the brake bicycle 20-percent hard to apply the lapp brake force to the tires. This could easily set up a condition where it would be about impossible to lock the brakes with the larger master cylinder .
What all this means is : if you are considering changing passkey cylinder sizes, even a 1/16-inch variety in piston diameter can have a drastic effect on braking performance.
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Of course, adding a front disk brake system to a cram brake car besides requires some type of brake coerce proportioning system to reduce the higher hydraulic pressure to the raise brakes. If a proportion valve is not employed, the high imperativeness will prematurely lock up the rear brakes under heavy brake .
many cheap front man disc brake conversion kits come with a factory-style combination valve that reduces the buttocks brake pressure. While this is surely better than no valve at all, it does not and can not account for the twelve or so variables that are integrated into your particular application. Let ’ s search at an exercise .
The combination valve normally incorporates an isolation valve in the arrangement. The isolation valve is controlled by the front and rear incoming bracken pressure. This valve has incoming brake pressure acting on each side of a piston. If the coerce on one english of the piston is more than the other side, the piston will start moving toward the lower pressure. At a preset point of piston motion, the bracken light warning switch is triggered .
Let ’ s say that we want to convert a 1964 El Camino from four-wheel drums to factory single-piston caliper front brakes by using a complete spindle and brake assembly from a 1969 Chevelle. While both cars share the same wheelbase, the El Camino is significantly lighter in the rear with its bed, putting less weight over the back tires .
In this particular application, this 1964 El Camino happens to be equipped with larger 11-inch rear drums and taller 275/60R-15 buttocks tires mounted on 15×8-inch wheels with 5.5-inch buttocks backspace. All of these are non-stock changes compared to a stock 1969 Chevelle combination valve and will drastically affect when the back brakes lock up during emergency brake .
This very forces the publish to employ an adjustable proportion valve for any front man disc brake conversion. You ’ ve probably read a normally used numeral that approximately 70 percentage of braking effort comes from the front brakes under hard brake. Weight transfer from the back of the vehicle to front makes braking force solid on the front brakes .
Despite this common belief, my experience with high-performance brake systems on early GM A-Body muscle cars reveals that a very large share of braking efficiency comes from those bantam 9.5-inch rear brake drum brakes. It pays large dividends to apply a much braking energy to the rear brakes as potential .
several upgrades can be performed to the 11-inch Chevelle rotor and floating caliper worldly concern that do not require thousands of dollars to achieve. A quality jell of performance 11-inch rotors attenuated with a jell of operation pads, such as those from Baer Brakes, EBC Brakes, Hawk Performance, Performance Friction Corporation ( PFC ), Raybestos, and many others, is a capital place to start. Look for a pad that has effective street characteristics, such as good cold friction and dependable initial feel with a clean secrete, one that is not noisy or exhibits excessive brake dust because that ’ mho precisely material you have to constantly clean off your wheels. There are respective brake pad manufacturers that offer brake pads that fit this class, including EBC Brakes, Hawk Performance, PFC, and Raybestos .
Companies, such as Wilwood Engineering, offer several different brake pad lines. From the low- and mid-temperature/ friction lines for street use to full competition high temperature/friction use. (Photo Courtesy Wilwood Engineering Inc.)
Another simple upgrade is to replace the stock OEM condom flexible lines with DOT-rated stainless steel sword hoses and fittings. These hoses do no parry under pressure and will help deliver a more upstanding brake pedal feel. several companies, such as Russell and Earl, offer low-cost stainless sword hoses. Just the change to new brake fluid, hoses, and brake pads can make a dramatic change to braking performance while keeping the monetary value under just what a pair of 14-inch rotors would demand. not everybody needs 14-inch four-wheel magnetic disk brakes with six-piston calipers .
Huge brakes have become the signature components of the Pro Touring push since the change by reversal of the twenty-first hundred. They look amazing inside a set of 18- or 20-inch wheels and those slots, holes, and dimples just add to the bling. But what ’ s very going on here ? Is all that in truth necessary ?
big rotor diameters do serve a useful aim. Brakes are much like a clutch in a manual-transmission car. The larger clutch adds surface area which adds holding might. A larger rotor increases surface area ( often called sweep area ), but more importantly, the diameter adds leverage. As diameter increases, this moves the caliper further off from the spindle centerline, which gives the caliper more leverage over the kinetic energy of the moving fomite .
Larger-diameter rotors besides demand larger-diameter wheels to clear the caliper. These are not hard and fast rules, but a 12-inch factory rotor and caliper will usually fit inside a 15-inch steering wheel. A 13-inch rotor box will sometimes suit inside certain 16-inch wheels and surely 17-inch wheels. The 14-inch rotor packages will demand at least an 18-inch-diameter rack, so keep these relationships in mind when choosing a brake rotor size. Bigger about always means more expensive, frequently in more ways than one .
Rotors with drilled holes are stylish and serve a purpose. Brake pads can outgas under heavy braking conditions. These drilled holes allow the brake gases to escape as the temperature rises.
Drilled holes are much thought of as stylish, but they do serve a determination. Under heavy brake, brake gases need a station to escape as the temperature spikes. unfortunately, these drilled holes offer an excellent starting plaza for tension cracks that will finally cause rotor failure. Rotor technology and materials help fight this, but a better theme is rotors equipped with dimples or slots cut into the rotor font. These depressions perform the lapp function as holes but do not offer the startle sharpen for stress cranks, which improves the rotor ’ s life anticipation. Most companies offer dimples and grooves as options for their performance rotors .
Cryogenics is another password that has crept into the high-performance vocabulary. Some claim that this subzero exposure of the metals helps align iron crystals and improve the lastingness of the metallurgy, allowing the rotor to better withstand the heat of senior high school brake temperatures. My research has led to no such results, and I have yet to find credible results that would lead to alike conclusions. While cryogenic freeze has its proponents, at this clock time many hush remain doubting. There may be better ways to spend your money .
The main advantage of larger, multi-piston calipers is a combination of extending the sweep contact area of a larger pad and adding pistons that can evenly apply the launching pad against the rotor. The main function of the caliper piston ( mho ) is to generate clamp load. Brakes make by a combination of coefficient of friction of the launching pad applied with a given load over a given area positioned by the diameter of the rotor. Longer pads with more come on area require more pressure and multiple pistons make that happen .
Another advantage of multiple piston calipers is that the load applied is spread out over a larger area on the pad, leading to more even pad wear. This is one of the disadvantages of the original big, single-piston GM calipers. A late initiation on multiple piston calipers is using a smaller piston on the pad ’ second leading edge followed by larger pistons toward the chase edge. This besides contributes to more even pad clothing since the leading edge of any pad tends to accelerate wear and it digs into the whirl rotor .
Calipers with multi-pistons provide braking force that is evenly spread across the contact patch, resulting in more even pad wear. Almost every aftermarket brake manufacturer offers a multi-piston caliper as well as a single-piston caliper.
Most multiple-piston calipers are of the two-piece assortment that are bolted in concert, frequently with a brake fluid transfer interface that must be sealed. This two-piece construction makes the caliper easier to build. According to several brake diligence experts, there are no real lastingness advantages to a mono-block or one-piece caliper invention since the real test becomes the manner the caliper is designed to resist the forces of press on both sides of the caliper, assuming a fixed-piston design that attempts to spread the caliper apart at the bridge where the caliper straddles the rotor. The bridge is any caliper ’ mho weakest point. So there does not appear to be any very forte advantage to a mono-block caliper .
This is an area that becomes a strange mixture of chemical concoctions that is heavily influenced by estrus, coerce, type of manipulation, and personal preference. It might seem that it would be easily to create a brake pad material that could do everything well, but as with most things in life, there are compromises. For exemplar, brake scatter, noise, cold performance, life anticipation, bicycle responsiveness, and a host of early details are all variables that affect the decision on a pad material .
A brake pad with a identical high gear coefficient of clash will surely improve stopping power and may perform well at identical eminent temperatures but might destroy a adjust of rotors in less than 10,000 miles. This is not a good choice for a street car .
There are literally a twelve or so brake pad manufacturers, and it isn ’ t possible to go into all the different configurations across all the major brands. If we were to break the pads down into categories, there are constituent ( non-asbestos ) pads that are generally the direct-replacement pads, semimetallic pads, and ceramic material. The material differences broadly follow increasingly higher temperature capacities for race .
While some racing products can be used on the street, when it comes to disc brake pad material, these are best bequeath for habit on entirely road race or circle track applications. Higher-temperature pads as a cosmopolitan rule do not work well on street cars because it ’ s rare for a street car to generate the promote temperature necessary to make a slipstream pad perform properly. other areas of importance for street-driven cars are scatter and noise, which are nonissues with race cars. so, leave the race embroider for the race cars and you ’ ll be better off .
One area that seems to garner a lot of attention is brake frisson or pedal pulsation. This is most often blamed on warped rotors. A egg white paper authored by notice subspecies cable car builder Carroll Smith claims that rotors rarely warp and that the pedal pulsation is caused by a buildup of brake pad material on the face of the rotor that creates high spots that become highly hard. These small peaks can be seen as heavily blue spots on the rotor that can not be removed by childlike brake lathe bleak because these spots are fabulously hard. If the rotor is a two-piece design where the rotor can be separated from the hub, then the rotor can be Blanchard grind and the hot spots removed. differently, the rotor must be replaced .
The best room to avoid the constitution of these hot spots is to properly bed in fresh brake pads and/or new rotors. This bedding-in summons creates sufficient estrus to transfer pad material from the pad to the rotor. This demands a gradual application of significant heat, and frequently the process will be noticeable enough that you will smell the brakes as they cook off the adhere agents portray in the pad material .
The crucial point when bed in pads is to avoid coming to a complete stop after heating the pads. A broad end at high temperature can create an impress of the diggings on the rotor, which could easily create the gamey spots the bed process intends to avoid. so, it ’ south important that the specific brake launching pad manufacturer ’ s bedding process recommendation is close followed .
It ’ s unmanageable to make any kind of a street brake pad recommendation since there are so many unlike pad materials and compounds. Companies with a solid reputation for quality products include Baer Brakes, EBC Brakes, Hawk Performance, Performance Friction Corporation, Raybestos, StopTech, Wagner, Wilwood, and many others. If you are abusing your brakes under autocrossing or chase day exercises, talk with some of the more-knowledgeable participants about their recommendations, specially if the slog will be used for both street and mild slipstream use .
The most crucial point is to choose a pad that will withstand the heat it will be exposed to so far still generate becoming cold-stop characteristics so that the brakes will work well the inaugural fourth dimension you step on the pedal. This is a characteristic that most race pads do not display, and it is the chief reason that rush pads should not be used on a street-driven car .
REAR DISC UPGRADES
It ’ second authoritative to not overlook the contribution of rear brakes to overall brake operation. many enthusiasts tend to focus on front man brakes while often ignoring the rears. For the average street car, rear cram brakes are very well but if you do want to step up there are some interesting and relatively cheap upgrades for the Chevelle and A-Bodies that will not lone offer improvements in braking world power but besides look good .
CPP offers several unlike versions of a single-piston float caliper kit, one in detail is separate numeral 1012RWBK-SE-6467 that includes a rear park brake kit out that is outlined in photos and captions with this article. There are several iterations of this kit available depending upon completeness .
Among the least expensive back magnetic disk brake swaps are several kits that use parts from the third- and fourth-generation Camaro. summit Racing ( part number SUM-BK1623 ) and Right Stuff Detailing ( part number AFXRD01 ) offer similar kits that supply the rotors, calipers, pads, mounting brackets, hoses, and even parking bracken cables. These kits are competitively priced at under $ 400. If you want to do the job yourself using a combination of used/junkyard parts and fresh components, it ’ s not very difficult .
The key component is the rear caliper mounting bracket that connects the buttocks axle house to the caliper. The factory application uses two different brackets, but we ’ ve found that the big, heavy, cast-iron bracket works identical well and bolts directly to the early 10- and 12-bolt A-Body rear axle assemblies. This will require removing the stock drum brake assembly, which means the hardest partially of this wholly conversion is removing the rear cover and pulling the C-clips to allow removing the buttocks axles. The new caliper brackets bolt in on the broth rear axle mounting flange. Slip the axle back in target, swoop on the rotor and the caliper, and the chief work is done. The only thing left to do then is to install the system of measurement flexible hose on each caliper. These use a unretentive flexible hose because the caliper is free-floating. Adapt the metric unit fit in the end of the hose to the arduous channel tee on the exceed of the buttocks axle .
This conversion is not in the least the only means to adapt rear disk brakes to a Chevelle. Baer Brakes, Wilwood, and many others besides offer aftermarket kits in versatile rotor diameters and caliper configurations. If you desire to maintain 15-inch rear wheels to mount puff race slicks, keep in mind that larger raise rotor diameters will demand larger-diameter wheels. This can sometimes cause difficulties when you want to run predominantly drag race–style 15-inch rear tires. The third-generation 11.5-inch rear disc brake kit out mentioned earlier is small enough to accommodate a 15-inch wheel .
This article truly just begins to describe some of the assorted phonograph record and drum brake options available to the enthusiast. not everybody wants or needs a six-piston caliper brake arrangement or flush four-wheel magnetic disk brakes. It all comes down to what fits your budget and your sense of how a lot brake you need for how you plan to use the car. The rest of it is merely manner.
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Written by Bobby Kimbrough and republished with permission of CarTech Inc
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