Our Baer Track 4 front brakes were installed back in the Feb. '11 issue. These feature Baer's large four-piston T4 calipers and 13-inch rotors. Of note is that they come preassembled with new hubs on new spindles—just unpack them and bolt them to your ball joints. Our rear SS4 kit with one-piece rotors was chosen to match the Track 4 fronts.
Upgrading your rear brakes means pulling the rear cover, pulling the C-clips and axles, disconnecting the parking brake cables, and unbolting the drum brake backing plates (four 9/16-inch bolts). This is a great time to inspect and/or replace axle bearings and seals, upgrade your differential, or swap gear ratios. Our 8.5-inch 10-bolt already has a 28-spline Detroit Truetrac diff with 3.73 gears and a main support girdle from Summit.
Reusing the OE T-bolts (if you still have them—we didn't), bolt the new Baer backing plate assembly to the axle flange. The SS4 kit uses a C5-derived parking brake/backing plate assembly, making future maintenance easy.
Right here is the genius of Baer's SS4 rear disc conversion: the mounting bracket and slider sleeve assembly. The inboard bolts attach the bracket directly to the backing plate (the new 19mm bolts take 85 ft-lb of torque), but you'll notice that the caliper mounting bolts pass through stainless steel sleeves. The sleeves insert into the hard-anodized bracket and allow the caliper to follow the rotor as the axle moves in and out of the rearend assembly.
With the backing plates and caliper mounting brackets attached, slide the axles back in, put the C-clips back in, bolt the rear cover on, and fill it with fresh lube. We used this opportunity to upgrade our separate axle bearings and seals with new Timken one-piece bearings. Check out PopularHotRodding.com for a web-exclusive story on this operation.
The SS4 rotors are zinc-washed cast iron, and are slotted, cross-drilled, and directionally vaned for cooling. They measure 12 by 1.1 inches, and are a good cosmetic match to the 13x1.1-inch Track 4 rotors up front. Baer also offers a kit with smaller 11-inch two-piece rotors for smaller 15- and 16-inch wheels, and a kit with 13-inch two-piece rotors for 17-inch and larger wheels.
Baer's S4 caliper is made of 6061-T6 billet aluminum and has four stainless steel pistons. It takes a common FMSI-size DR1 pad (the SS4 comes with Hawk HB100 pads), and can be mounted on either side, since there are bleeders at both ends. The brake line attaches to a billet 5-psi residual pressure valve (shown in black on the side), which helps maintain the pad in close proximity to the rotor. The S4 calipers mount to the brackets with two included 19mm bolts torqued to 85 ft-lb.
Baer includes quality Goodridge braided stainless steel hoses in its kits. The caliper end terminates in a banjo fitting, which must be attached to the residual pressure valve via a hollow banjo bolt and two virgin copper crush washers. It's critical to orient the hose and banjo fitting correctly (i.e. away from any possible interference) on the first attempt because the crush washers may not be reused.
Take note of the completed plumbing; the factory brake line has been bent to meet the new braided stainless brake hose at the mounting clip, which has been attached to the axle with a new hose clamp. While the factory line was disconnected, it had been capped with a small rubber nipple provided by Baer in the kit. This prevents fluid from draining out and soaking the floor.
The parking brake cables attach to the backing plates and hook around the parking brake levers on both sides, and into the factory brackets on the chassis end. They attach on brackets at either end with a circlip.
Although the parking brake cables in Baer's '73-77 GM A-body kit are ostensibly the same ones in their '64-72 GM A-body kit, they also work on the longer late-model A-body wheelbase by moving the tension cable hook farther down the perimeter frame. (We moved the hook from the thin slot to the large circle in the foreground.) This frees up enough cable to allow both sides to be connected and subsequently tightened.
All bolted up to our 8.5-inch 10-bolt rear, our SS4 kit is ready for the street and the track—all we had to do is bleed the system with fresh DOT 3 fluid. It's important to note that we upgraded our master cylinder back when we installed the Baer Track 4 front brakes. The stock 1⅛-inch master was swapped for a smaller diameter 15/16-inch CPP master cylinder (PN 6150012, $115) in preparation for the rear disc conversion. The smaller master will generate the higher pressure we need for more aggressive stopping.