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Braking To Avoid Breaking: Part IIIPart III: Moving forward on our rear disc brake swap and front disc brake rebuild From the January, 2009 issue of High Performance Pontiac By Thomas A. DeMauro Illustrators: Diagrams Courtesy of GM
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Rebuilding and upgrading the braking system in our '77 T/A has been a rewarding yet arduous endeavor. One advantage we had was the fact that the Pontiac is partially disassembled. Nevertheless we have been working on it for months. Those who read Part I and II know that Stainless Steel Brakes Corp, Year One and Classic Tube provided many of the components to upgrade to rear disc brakes, stainless steel lines, Power Slotted front rotors and generally to rebuild the system with stock replacement parts where required. The remainder was purchased at local auto parts stores, as needed. As you have seen, not everything is as easy as it would seem. Sometimes, a bit of tweaking or more parts are necessary to make everything work together, as it should. In the case of the emergency brake system, substantial modification was needed, but we showed you how we did it in Part II, so the process should be easier for you. In our final installment, we will mount the adjustable proportioning valve for the rear disc brakes and move forward to rebuild the front braking system. We used a disc/drum brake master cylinder and combination valve because most of you would retain yours and the rear disc system is sold to work with them. Much of this is basic, but we will employ a few upgrades, discuss pitfalls and even provide some procedures that may save you time and money should you decide to tackle a project like this on your own. See the photos and captions for details.  Shown is the front brake line...  Shown is the front brake line configuration as per the service manual. Note the torque values for all of the fittings and fasteners.  Picking up where we left off...  Picking up where we left off in the last installment, here is the adjustable proportioning valve that was provided by Stainless Steel Brakes Corp. for our rear disc brake kit. According to the company, the rear disc brakes require a higher line pressure (1000-1200 psi) than the drum brakes (600-800 psi) we replaced. SSBC says many factory combination valves containing a proportioning valve will provide the needed pressure and that the SSBC adjustable valve is used to fine tune the system by dialing down pressure as needed. If your factory proportioning valve does not provide adequate pressure then it must be bypassed and the rear line run straight to the SSBC adjustable proportioning valve. A combination of self-tapping screws and washers are employed to mount the valve.  The 1/4-inch diameter front...  The 1/4-inch diameter front to rear stainless steel line from Classic Tube was installed to determine where to place the proportioning valve. A line clamp and hardware kit from Year One saved us from finding and cleaning the old parts thereby making installation a breeze. As you see, we installed the front to rear stainless steel fuel line at the same time since the clips hold the fuel line in place too.  It's important to find a location...  It's important to find a location to mount the valve that is easily accessible and safe. The best spot we found was up front on the driver's side floorpan between the subframe and the outer lip where the floorpan meets the rocker panel. This area is relatively flat and protected. Once we decided where to position the proportioning valve, we marked the line's spring wrap with tape to show where the seat fittings end. We also marked the line itself inside the spring with a Sharpie since the spring wrap can move.  The seats and line fittings...  The seats and line fittings supplied for our proportioning valve were 3/16-inch diameter (left) but our front to rear stainless steel line is 1/4-inch so new seats and fittings (right) were purchased at the auto parts store for $4.  After cutting, installing...  After cutting, installing the fittings and double flaring (see sidebar) each end of the front to rear line, the two pieces were reinstalled. Two holes were drilled in the floor and the proportioning valve was mounted using the self-tapping screws and washers shown earlier. The line fittings were screwed into the seats and tightened with a line wrench to finish the installation. Loctite was used on the seat fittings where they screw into the proportioning valve.  Moving forward, we replaced...  Moving forward, we replaced our old brake power booster with this rebuilt unit from Year One. It came with a few warnings, as shown. Though padding and a foam cylinder are provided to keep contaminants out of the booster in the rear, the plastic dust boot is not. Ours was pretty well wasted so another one was found.  Our master cylinder was purchased...  Our master cylinder was purchased new from the local Napa auto parts store. It is the same piece that Year One uses as a replacement for the Trans Am with factory installed rear drum brakes. A new master cylinder requires bench bleeding, which consists of filling the wells with fresh fluid to 1/4-inch from the top, installing temporary lines and fittings that place the lines in the fluid and then stroking the cylinder 1-inch in and out. Repeat until the bubbles stop coming up from the submerged lines and the piston no longer moves in more than 1/8 inch. We used Napa's master cylinder brake bleeding kit shown here to ease the process. The handle of this Craftsman ratchet was shaped perfectly to fit the depression in the rear of the cylinder. A wooden dowel works well also.  Since we are not worried about...  Since we are not worried about concours correct, we simply painted the booster semi-gloss black and bolted it in. Don't forget to hook up the pedal to the rod inside the vehicle. The booster is delivered with complete installation instructions including the proper method by which to determine whether the pushrod is the correct length and how to lengthen or shorten it.  Though our brass replacement...  Though our brass replacement combination valve from Year One looks different than an original cast-iron piece, it performs the same functions. A metering section in the combination valve holds off the pressure to the front disc brakes until enough pressure is built to the rear brakes to over come the pressure of the rear brake shoes' return springs. This allows the shoes to take up the clearance between them and the drum surface. The proportioning section of the combination valve adjusts outlet pressure to the rear brakes once a predetermined pressure is reached, to avoid rear brake lockup. According to the service manual, some models with high rear wheel loads don't have the proportioning feature. A bypass is designed into the valve to ensure that the rear brakes receive full pressure in the event that the front brakes fail and vice versa. A pressure differential warning switch monitors the front to rear brake pressure differences from the master cylinder and illuminates a brake warning light on the dash if a pressure drop is present.  The master cylinder is installed...  The master cylinder is installed next, along with the bracket for the combination valve and the lines and brackets. We kept the bleeder kit in place to avoid leakage on the new parts. Our stainless steel lines from Classic Tube fit perfectly. The bracket on the frame holds the junction of the hard line and the flexible line for the driver's side caliper. A U-clip secures the lines to the bracket.  Be sure to use a line wrench...  Be sure to use a line wrench on all of the fittings, to avoid rounding their edges as shown here on the master cylinder fittings.  To deliver brake fluid to...  To deliver brake fluid to the passenger side caliper, this hard line runs from the combination valve to a bracket mounted on theframe rail.  This bracket will secure the...  This bracket will secure the junction of the hard line to the flexible line on the passenger's side. A self-tapping 1/2-inch head bolt holds it in place. The hard line can be seen over the top of the ratchet awaiting installation.  Our spindle is of 1979 vintage,...  Our spindle is of 1979 vintage, which will become important in a moment. The ball joints and tie-rods are from Performance Years.  First to go back on was the...  First to go back on was the splash shield for each side. We just stripped and repainted ours and reinstalled them. There is also a small gasket that is placed between the shield and the spindle. Don't forget to replace it as well. Year One has it.  In 1979, according to the...  In 1979, according to the service manual, the thickness of the spindle was increased and therefore requires a different set of bearings and a new rotor to fit it. Here is a '79 bearing trying to fit into a '77 and earlier rotor. No dice. Just be aware of this when you are shopping boneyards or swap meets for spindles and front brake parts. That's why it was important to mention that we were using 1979 spindles.  Our front rotors were delivered...  Our front rotors were delivered from SSBC with the inner and outer races already pressed in, which simplified installation. Once the inside of the rotor is loaded with wheel bearing grease, the wheel bearing is packed with grease as well. It can be done with a tool made for the job or the old-fashioned way--by hand. Just load your palm with lots of grease and knead it through the bearing rollers until all areas of the bearing are covered.  With the inner bearing installed,...  With the inner bearing installed, the wheel bearing seal is tapped into place.  The outer bearing, the washer...  The outer bearing, the washer and the castle nut will be installed on the outer side of the rotor once it's mounted on the spindle.  After all of the parts are...  After all of the parts are installed, the bearings need to be seated. This was done by slowly tightening the castle nut to 12 lbs.-ft. while turning the rotor. Then the nut was backed off and hand-tightened and, finally, we backed off just until the cotter pin could be installed. This adjustment sequence is from the Pontiac service manual. From .001 to .005-inch end-play will be present when the bearings are adjusted correctly.  Once the cotter pin is installed...  Once the cotter pin is installed and the ends are bent so that it doesn't walk, the dust cap is lined with grease and tapped into place. Here is the finished product from the passenger's side. You can also see the Power Slot design of the rotor that we discussed in Part I of the article. As is true with the rear rotors, the Power Slot front rotors, according to SSBC, promise to reduce brake fade through increased heat dissipation and provide better wet braking and increased pad life.  Our calipers are stock replacements...  Our calipers are stock replacements from the auto parts store. For a fee, Stainless Steel Brakes Corp. can rebuild your old calipers and install its stainless steel sleeve and piston in each one. Note how the caliper is equipped with a guide on the back near the banjo bolt hole. This is to direct the flexible brake line.  Carbon Metallic pads were...  Carbon Metallic pads were provided by SSBC as an upgrade over the stock replacements. These pads resist fade much better and last longer than stock. With the anti-squeak plates installed, the pads pop into place as shown by squeezing the tangs of the support spring. Also note the inboard pads are specific to the left and right sides of the T/A, as the warning sensor on each pad must be installed toward the rear of the caliper to avoid contact with the spindle.  After new hardware, rubber...  After new hardware, rubber bushings and sleeves are installed, and the calipers are mounted over the rotor and fastened to the support bracket of the spindle with long slide bolts, which take a hex headed socket to tighten. This setup is what is commonly referred to as sliding calipers, since they slide on the bolts. The bolts are torqued to 35 lbs.-ft. Once the calipers are installed, the tabs on the outer pads are bent over flush to the caliper.  For longevity, we ordered...  For longevity, we ordered stainless steel braided lines from SSBC for the front brakes. Though you saw rubber lines on the rear brakes, they will be changed once the stainless lines arrive. The reason that we say for longevity and not for a harder pedal feel is that SSBC states that stainless braided lines do not contribute to pedal feel. According to the company, the stock rubber lines have a nylon webbing inside that can withstand 3000 psi. so they will not expand under pressure any more than the braided lines. As was the case with the rear, a banjo bolt secures the lines to the calipers with a brass washer on either side to seal it. Note that the end of the line is contoured, to fit the caliper in one direction only. The washers can only be used once.  The hard line is attached...  The hard line is attached to the stainless braided line as shown, after sliding through the retaining bracket on the frame. The junction will then be slid back into the bracket and captured with a U-clip. A line wrench will be used to tighten the fittings. It's easier to mate the hard and flexible line before the flexible line is locked into the bracket. Once the flexible lines are installed on both sides, turn the front wheels left and right to ensure that the hoses don't rub on any suspension parts.  After all is said and done...  After all is said and done and everything is tight, you must bleed the brakes. We will try this trick MITYVAC kit from Year One when the time comes. You can do the same, or you can bleed the brakes the traditional way. Pump the pedal a few times and then hold it down while a friend opens the bleeder screw to release the air and fluid through a hose attached to the screw, into a clear jar half full of fluid in which the other end of the hose is submerged. Start at the caliper furthest from the master cylinder and work toward it. Just make sure that the master cylinder reservoirs maintain at least a 1/2 full fluid level during the process. How To Double Flare Brake Lines  We then deburred and chamfered...  We then deburred and chamfered the edge on a grinder to prepare it for flaring. After the appropriately sized fitting was slid onto the line, it was then installed in the flaring tool in the hole that matches the size of the line. The flaring bar is then tightened around the line using the wing nuts, so that it doesn't slip during the flaring process. Our double flaring tool was provided by Year One. As per its instructions, an amount of line equal to the height of the step on the adaptor for the line size (shown next to the tubing end) is left exposed.  Once the outer spring protection...  Once the outer spring protection was clipped and removed and the line marks that we made earlier were located, the line was cut using an inexpensive tubing cutter. Since our marks represented the outer ends of the threaded seats, we had to leave space for the depth of the seat from its outer edge, the 1/8-inch of line needed to create the double flare and enough space to cut off the flare and start over in case we screwed up. With all of this considered, we cut about an inch to the inside of each of our marks, leaving plenty of room for error. A line that is slightly too long can be worked with. One that is too short is junk.  Here is the result of the...  Here is the result of the first forming, which is bell-shaped.  The first flare is performed...  The first flare is performed using the aforementioned adaptor, which is tightened using the yoke assembly until it is against the flaring bar of the tool. With soft factory style lines, it is a relatively easy process. With hardness of the stainless lines, flaring is more difficult. Locking the flaring bar in a vise is recommended and sliding a short length of pipe over the handle used to tighten the attachment will provide some moreleverage.  The flare is performed by...  The flare is performed by removing the adaptor and tightening down the swivel of the yoke into the bell-shaped tubing end.  The result should look like...  The result should look like this. Be sure that the flare is even all around and that it will seal to the seat and the fitting upon installation. Check for any leakage around the fitting after installation. Final Words
Whenever you work with brake systems, safety is key. Once the installation is complete, take the time to check and recheck the instructions, the torque on all fasteners and for the presence of leaks in the lines. Make sure that the brakes actuate, as they should. Also don't forget to adjust the parking brake per the instructions. Once on the road, and after you have determined that no other brake problems exist, Stainless Steel Brakes Corp. recommends that the adjustable proportioning valve be set to full "increase." Then make some test stops and adjust the pressure down until the front and rear brakes lock up at the same time. If everything was installed and adjusted correctly, the braking improvement should be dramatic. We will let you know our opinion once we get the rest of the T/A assembled.
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Stainless Steel Brakes Corporation
11470 Main Rd.
Clarence
NY
14031
8-00/-448-7722
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