In our May 2003 issue, we presented our in-house '67 Camaro in all its four-wheel drum-braked glory, along with the quandary of merging aftermarket disc-brake upgrades with stock-type wheels. The fact that this car is used for the daily slog through L.A. led us to outfit it with good ol' Chevy rally wheels rather than big-inch/low-profile rollers. The steel wheels and relatively tall tires cope well with road maladies typical of the sprawling metropolis, and let's face it--they're cheap. The problem was, retaining 15-inch wheels severely limited our choices for brake upgrades, since most performance disc systems require at least a 16-inch wheel. We've got nothing against modern wheel/tire combos, and may even upgrade the Camaro to 17s in the future, but being required to run them all the time was a concern with this daily driver.
The solution came to us at the 2002 SEMA show when we spotted the latest addition to Baer Inc.'s Serious Street line of brake upgrade packages. The system features the same PBR dual-piston aluminum calipers used with many of Baer's systems, but combines them with 11-inch rotors to minimize the overall dimensions of the system, allowing it to package within the confines of a 15-inch wheel. We tested the Camaro's stopping distances from 60 mph to zero, and from 100 mph to zero, first with the stock drums and then with Baer's front-disc upgrade, though still without a power booster. The improvements were dramatic (check the sidebar for details), but the rear drums were prone to locking up under extreme braking.
For the next phase, Baer installed one of the its Rod & Drag rear brake systems to complement the Serious Street front brakes. The Rod & Drag system is as complete as the front system, and includes EradiSpeed directionally ventilated 11-inch rotors, PBR aluminum single-piston pad-guided calipers with integral parking brake, Teflon-lined braided stainless-steel flex hoses, vehicle-specific parking brake cables, and all necessary mounting hardware. Though Baer handled the installation for us, the process is relatively simple, as we've outlined here.
We tested the Camaro again, first with the addition of the rear discs, and then again after adding a vacuum power booster. With each step, braking continued to improve. The results are listed in the accompanying sidebar, along with the averages from the first round of testing. Overall, the Camaro has become a much more capable stopper, performing on par with a late-model Z28 from 100 mph. In the process, it has also become more enjoyable to drive, in part due to the addition of power brakes. Check out the details.
Our Camaro's stock drum brakes were rebuilt just prior to the rear-disc upgrade to more accurately evaluate their stopping abilities. However, despite the new shoes, springs, and drums, the drum brakes really didn't perform substantially better than the somewhat worn assemblies we tested for the May issue. The problem seemed to lie with the difficulty in modulating the rear brake effort after building heat from repeated stops. Simply put, the rear brakes locked up very easily under extreme stopping conditions. Part of the problem was the Camaro's tendency to unload the rear axle as it nosedived under hard braking. |
Complementing its Serious Street front disc system, Baer's Rod & Drag rear-disc system increased our Camaro's braking capability and resulted in better overall control of braking effort. The Rod & Drag hardware easily packages inside a 15-inch wheel with single-piston aluminum PBR calipers and 11.35-inch rotors. The system includes everything needed for installation, including braided stainless-steel, Teflon-lined flex hoses and new cables to mate the PBR integral parking brake with the Camaro's factory parking brake linkage. |
Installation of the rear-brake kit requires that the axles be removed so the mounting brackets can be bolted to the axlehousing. Most Chevy rearends of this era used C-clips to retain the axles, which are accessed inside the differential housing. After pulling the differential cover and draining the fluid, carefully loosen the small bolt that retains the differential cross-shaft (arrow), and slide the shaft out far enough to allow the axles to be pushed in toward the center. |
With the axles pushed in, the C-clips can be removed from the ends of the axles. |
A magnet works well for fishing them out. Once the clips are off, the axles can be slid out of the axlehousing. |
After the axle shafts have been removed, the drum-brake assemblies can be removed. First, disconnect the parking-brake cables. |
Then remove the cable housings from their mounts on the frame. Remove the four bolts holding the brake backing plates from the axlehousing and pull the drum brake assemblies off as a unit. |
The new caliper brackets mount to the axlehousing using the same mounting flange and hardware that retained the drum backing plates. However, the caliper brackets are drilled with two sets of mounting holes, allowing the caliper to be positioned slightly above or below center. In either case, the calipers mount toward the rear of the vehicle. Most applications with multileaf rear springs will require that the caliper be mounted below center, but our monoleaf car allowed above-center mounting. |
Before reassembly can continue, the axle flanges must be modified. Using a lathe, the flanges are turned down to a 5.9-inch diameter so they will fit inside the "hat" of the new rotors. The procedure can be performed by a typical automotive machine shop for a nominal fee. Make sure to test-fit the rotors, paying special attention to the axle stub, which will center the rotor on the axle shaft. The stub may require slight cleanup with a file for proper fitment. |
Once the axles have been modified, the axles and differential are reassembled and filled with fresh fluid. This is a good time to check the condition of the axle bearings and seals and service accordingly. With the rear axle assembled, slip the rotors onto the axle flanges and secure them with two lug nuts. |
The Baer system includes brackets with adapter fittings to mate the factory hard lines with the new flex hoses that fasten to the axlehousing with clamps. Position the clamps approximately halfway between the leaf spring and the axle flange, and then carefully bend the factory hard lines so the fitting is pointing straight down and can be threaded to the adapter. If the existing hard lines are rusty, kinked, or otherwise trashed, replace them. |
The clearance between the rotor and the anchor must be checked to verify that the mounting bracket is located squarely on the axlehousing. In rare instances, some factory axlehousings may have flanges that are not perfectly aligned. Once the caliper and anchor are in place, use feeler gauges to measure the clearance between the anchor and the rotor on both sides of the rotor and both ends of the anchor. Minimum clearance is 0.030 inch, and the maximum is about 0.090 inch. If your measurements fall outside of these parameters, it may be necessary to use shims (available from Baer) to obtain the desired clearance. |
With proper caliper anchor clearance established, torque the anchor mounting bolts to 85 lb-ft and then install the Teflon-lined braided flex hoses. The flex hoses thread onto the adapter fitings on the axletube and mate to the calipers using banjo-type fittings. Make sure to use a copper crush washer (included) on each side of the banjo fitting and torque to 15-20 lb-ft; over-tightening will break the fitting bolts. |
The final assembly steps involve connecting the new parking-brake linkage. The Baer system includes a pair of new brake cables to adapt the PBR caliper's internal parking-brake mechanism to the host vehicle's existing linkage. First, hook the squared cable eyelet to the parking-brake lever on the caliper, and then pull the cable sheath back and seat it in the bracket on the caliper, where it is fastened with a retaining clip. The other end of the cable simply connects to the original cable union just ahead of the axle, and is retained to the frame bracket with the original clip. |
Making the change from manual brakes to power on a typical GM car like our '67 Camaro is quite simple. First, the manual master cylinder is unbolted from the firewall and its pushrod disconnected from the pedal. |
Baer's power boosters are built to its own specifications. This is a dual-diaphragm unit, similar in design to an early '80s GM booster, and typical of the style found on G-bodies and F-bodies. However, the firewall bracket is application specific and the master-cylinder mounting studs are standard thread, rather than metric. The booster mounts with the two studs used to mount the manual master cylinder, plus the additional two studs beneath them. |
The brake pedal on most GM cars of this era has two pushrod holes: one for manual (A) and one for power (B) applications. Now is a good time to check the condition of the pedal bushings and replace them if worn. Baer recommends using a little grease to lengthen the bushing's lifespan. |
A new power-brake master cylinder is used, which does not have an integral pushrod. Instead, the power booster houses the pushrod. The master cylinder is bolted on, the lines attached, and the system bled. All that remains is to find a constant manifold vacuum source from the engine. |