Finned Aluminum Buick Brake Drum Install Tech Article
Installing the finned aluminum Speedway drums on an existing set of F100/early ford backing plates is as easy as a service replacement. The dimensions of the drum match the critical dimensions of a factory Ford cast iron drum. While the looks externally will match with a 1950's Buick, the center bore register of the drum matches the register on the 1940's style hub, 91065450. The back of the drum is made to clear a self-energizing 1937-48 Ford backing plate, such as 91065420.
As delivered the 45-fin aluminum brake drum is ready for use with no additional machining, clearance or alterations necessary. For best results in bedding the new drum to the brake shoes, thoroughly clean the drum to remove oils left from manufacturing and to prevent rust. A parts washer, followed by rinsing in water or a can of brake cleaner will do the job.
If you are replacing iron ford drums on an existing system, please prepare your existing brake system to ensure the best install outcome. While the drum is off, inspect brake shoes for wear, check for a small amount of grease between the contact points of the shoes and wheel cylinder/adjuster. Re-grease by hand if necessary. Turn brake shoe adjuster to its minimal width to retract the shoes inward to easy install.
This is a great time to remove the hub dust cap and assess the condition of the wheel bearings and grease. With the wheels chocked and axle fully supported by jack stands, attempt to move the hub inward and outward, checking for excess play in the wheel bearings. Worn bearings cause the front wheels to flutter and feedback through the steering wheel. If play is present, but minimal miles are on the bearings, remove spindle cotter key and tighten the spindle nut. If the bearing is past its service life, unknown mileage, or fails inspection, replace (91065455). Repack bearings if needed and re-install hubs. We took this opportunity to paint our hubs to match the car as they were visible through the center of the chrome reverse steel wheels.
Cleaned drums can now be installed on to the hub assembly and backing plates. These drums feature factory Ford 5x5.5” wheel pattern and will install easily on 1937-48 Ford OE, F-100, and similar aftermarket backing plates (91065420). They have been manufactured with the same dimensions, offset and clearances as a normal cast iron drum of the same fitment. While installing the drum on to the hub, pay close attention that the face of the drum is sitting flat on the hub surface. Do not force the drum on to the hub with a rubber mallet or pressure. If it does not fully install, remove and take a look to see where the interference is. The ID of the drum is a tight tolerance to the Speedway hub 91065450 (copy of a ford OE hub). This tolerance is kept tight to center the drum on the hub, rather than the lug studs, which can cause vibration and misalignment. It is acceptable to emery cloth or buff the inside of the drum centering register to open tolerance up for a smooth install. DO NOT force the drum on to the hub.
Spin the assembly by hand quickly and then let it freewheel to a stop. There should be no brake shoe engagement yet, as we have not adjusted the shoes outward to touch the drum. The drum and hub should spin several revolutions after it’s up to speed and stop due to bearing preload & grease. If it is difficult to spin or stops suddenly after freewheel, the preload may be too tight or the brakes are dragging.
Adjust brake shoes outward through the access port in the back of the bottom of the backing plate (brake tool kit 91604006 is a great addition to your toolbox). Adjust the shoes outward several revolutions and spin the drums again. You should start to feel and hear the drag of the brake shoes on the drum. Back adjustment up to the point where they are 1/4 turn adjustment away from contact and spin freely. It is crucial at this point that your brakes do not drag in any way. The break-in procedure will heat cycle the brakes and if any of the shoe is still in contact through the heat cycle, the shoe can separate and bond to the drum causing poor brake performance.
Pump brake pedal. If the backing plates and wheel cylinders were already on the car there should be an immediate high pedal, the same as your former drums. If the backing plate is a new install, follow bleeding instructions included with the brake kit.
Roll the car out of the shop. Start the car and allow it to warm up. Before shifting into gear, hold your foot on the brake pedal to verify the brake system is functional as you shift into gear. If the car immediately moves with no control from the brake system, shift back to neutral, turn the car off. This is an easy failsafe I do on any car I do brake work on, it takes no effort to be paying attention. Sure the brake pedal feedback shows us we have good brakes, but it doesn’t cost anything to have a plan and be safe.
Whenever testing any component of your classic, please take caution to find a secluded or low traffic area, or parking and observe all traffic laws. Accelerate to approximately 20 mph, drag brake slightly to decrease speed. Add throttle back to maintain 20 mph range. Drive for approximately a block and remove brake pressure. After approximately a 3 minute cool down period of no/minimal braking repeat brake drag procedure. Typically, I repeat this process for 2 or 3 cycles depending on when I can feel the brakes have gotten hot enough to bed in the two materials together. If you can smell the brake shoes bedding in, it’s time for a cool down period.
It’s very important that when you return to park your car for the cool down that the shoes are not left touching the drum liner as with the heat they can bond slightly to the drum. The parking brake should be set but avoided if it’s a hydraulic park brake which will reengage your fully heat soaked shoes.
The last step is to sit in the garage chair and take a look at your new vintage aluminum finned brake drums. Please leave us an online review of our new product to help explain your experience. Our install was a breeze and quite a rewarding project!