Part 4 - Saturday Brake

After months of searching for all original ACDelco brake system parts for my 1978 Pontiac Trans Am, I have finally found and acquired all the parts needed to completely replace my entire brake system.

ACDelco Brake Parts Collection

Thanks to ACDelco's online catalog, Amazon.com, and ebay.com, finding all the parts was easier than I thought it would be. I am trying to avoid any aftermarket parts, I prefer to put the car back in all original condition with all the correct parts. Original brake pipes are not available so I found a company in Michigan inlinetube.com that reproduces brake lines, fuel lines, and any other pipes you need for your older cars. I purchased stainless steel brake pipes so they will not rust.

The old drum brake parts after being washed off with a brake cleaner

My oldest son and I began the brake system teardown today. We removed all the brake hardware, rotors, drums, hoses, pipes, emergency brake cables, and combination valve. I had already replaced the brake vacuum booster and master cylinder with GM restoration parts.

Right Rear axle seal leaking

We discovered that the left axle seal has a small leak, so I have to order seals, gear oil, limited slip additive, and an axle cover gasket and replace them before we reassemble the brake system.

Original Nylon Injected U-Joints.

In the process of working on this car, we discovered that the original nylon injected u-joints are still installed in the driveshaft. When this type of u-joint gets replaced, the new u-joint uses internal snap rings to hold the u-joint in place. These u-joints have no snap rings and have never been replaced.  Why does this matter? The odometer of the vehicle shows approximately 55,000 miles. I doubt this car only has 55,000 miles on it, but it definitely is not a high mileage car.

Measuring rotor thickness of 1.004 inches 

Continuing my quest for an idea of how many miles this vehicle really has on it, I decided to measure the brake rotor thickness. These rotors appear to be original GM brake rotors, if they had been replaced, it is unlikely that most people would purchase original GM rotors because they cost more than aftermarket rotors.  Working on that assumption, new rotors are 1.030 inches thick. 

Motor minimum thickness specification casting

The minimum thickness (discard dimension) of the rotor is 0.956 inches (as shown in the above photo. The left front rotor measured 1.004 inches. This means that 0.026 inches of material has worn off of this rotor.  In my many years of teaching for General Motors, they taught us that you should allow 0.030 inches of rotor thickness loss for each set of brake pads.  The brake pads on this vehicle were not the original brakes, but is is possible that they are the second set of brake pads since the rotor. There is still enough rotor material left on this rotor for another set of brake pads to wear down. This tells me this vehicle is not a high mileage vehicle.

The right front rotor thickness measured 0.992 inches, a full 0.012 thinner that the left front

 The right front rotor thickness has worn down down to 0.992 inches. The discard dimension of the rotor is 0.965 inches. This thickness does not allow for 0.030 inches of rotor thickness decrease for wear. The rotor needs to be replaced.  I am replacing both rotors and drums.

Left front steering spindle with all brake hardware removed.

While the brake system is disassembled, I am going to clean and paint the backing plates, rear axle housing, sub frame, control arms, sway bars, and most of the under body.  We had to remove the inner fender wells to access all the brake pipes and hoses we are replacing. We removed all the hoses and pipes today.

My leaking fuel tank - One more thing in the never ending list of repairs on this vehicle

 This week I also discovered the source of gasoline fumes coming from my car. I had replaced all of the rubber hoses, installed the proper factory spring clamps, replaced the fuel tank cap, and a cracked evaporator emissions canister. I still could smell gasoline vapors. 1978 emissions regulations required a closed evaporative emissions system, so I knew there had to be a leak I was not seeing. I decided that the only place left was on top of my fuel tank.

Fuel leak at tank vapor line

We removed the fuel tank and found a huge leak were the vapor line connects to the tank. It is not something I wanted to repair or to have repaired. We also found another rubber hose on top of the tank that needs to be replaced. I was disappointed to not find my car's "Build Sheet" on top of the fuel tank. My last hope for the sheet is in the seat frame, but the upholstery has already been replaced and it is unlikely that it will still be there. I won't have time to check the seats for several weeks.

The New Fuel Tank waiting for the fuel level sending unit to be installed.

I looked online for replacement fuel tanks and found a reasonably priced new tank; I ordered it. It showed up yesterday.

Rear underbody with fuel tank removed

I will install the new fuel tank in a week or so after all the cleaning and painting. I want to paint the underbody above where the fuel tank is mounted. You can see the rear portion of the new exhaust system in this photo.

Blower motor and heater core are accessible with the inner fender removed

With the left front inner fender well removed to remove the brake pipes, I photographed the inconvenient location of the blower motor and heater core I referred to in Part 2 of this blog.

The ACDelco replacement blower motor for my Trans Am