BASIC BRAKE WORK?
Over the 20 some years I have been working in the automotive hobby, I have learned that the term "Brake Job" does not mean the same thing to all that perform them. For some hobbyists, it means the replacement of just the shoes or pads. In this article you will learn what is required to successfully complete a true "Brake Job".
Our subject vehicle is a 1969 F-100. In our project, we will cover the rebuilding of the Bendix style brake. The Bendix brake is the most widely used style of brake on both classic and modern vehicles equipped with drum brakes. Shown here is a Bendix Type 6 Brake.
Though the focus here is on the Ford F-100 , the principles are the same with most drum brake applications. Even if your classic is equipped with a different style of brake, such as Wagner or Lockheed, many of the concepts shown here can be applied to these applications.
Bendix.GIF (98691 bytes)
Bendix Type 5 Brake
The TYPE SIX Bendix Brake with Fixed Anchor & Self-Adjuster is the brake we will be rebuilding on the F-100. While there are several variations of this brake, they are all very similar.
In this type brake, the self-adjusting mechanism is attached to the secondary brake shoes in all four wheels. The mechanism consists of a cable eye, cable, cable guide which is attached to the secondary shoe, adjusting lever, and spring. The cable eye is fastened over the anchor pin between the two brake shoe retracting springs. The cable wraps around the cable guide on the secondary brake shoe and continues down to the adjusting lever.
The star adjuster spring connects the primary shoe to the adjusting lever instead of to the secondary shoe as in brakes with no automatic adjusters. The automatic adjusters operate only when the brakes are applied with the vehicle moving in reverse direction, and only if the secondary brake shoe moves away from the anchor toward the brake drum beyond a predetermined point. In other words, whenever the clearance between the lining and drum has increased sufficiently through lining wear to result in excessive travel of the secondary shoe.
The movement of the secondary brake shoe away from the anchor pin allows the cable to pull the adjusting lever in an upward direction against the end of one of the notches on the star wheel adjuster. The travel of the lever increases as the lining wear increases and, when the lever can move upward far enough, it passes over the end of the notch and engages into the next one. When the brakes are released after the car comes to a complete stop, the spring at the star adjuster pulls the adjusting lever in a downward direction, turning the star wheel and expanding the brake shoes.
The springs are color coded to identify their tension rating and placement in the brake. Never discard any of the helper springs or self-adjuster hardware.
Now if your going to flat out replace every component, you can skip the inspection. But if you're like myself and you are doing your own brake work to save a little money, the inspection is a must.
The worst part about doing brakes, in my option, is the inspection. I say it's the worst part, because you have to remove the drums and inspect the brakes. This phase is dirty, time consuming and in many cases you have to put everything back together if you don't have another vehicle to run parts.
We began the inspection by pulling the drums and inspecting the linings and brake surfaces. For the rear brakes, this is pretty simple. Safely jack the vehicle and remove the rear wheel. For the front, the inspection is a little more involved since the hubs need to be removed.
F100_4.jpg (9271 bytes)Prior to removing the drums you will need to adjust all the brakes down. This will allow the linings to clear the drum for removal. This step takes a little time, but it's well worth the effort. I have watched people pry the drums off the linings, destroying springs and bending back plates rather than adjust the shoes down.
For the rear brakes you many need to check to see if there is a retaining clip on one or more of the axle lugs. This clip was used to hold the drum in place until the wheel could be bolted on while on the assembly line. It no longer serves a purpose and can be discarded. On the older vehicles, these clips have long since been removed. If not, use a small chisel to the cut the clip. The clips are made of a light spring steel and cut easily.
The rear drum can be stubborn if there is any rust build up around the axle hub. Wire brushing and penetrating oil makes short work of this problem. You make need to tap the drum lightly with a soft or dead blow hammer to aid in it's removal from the axle.
As mentioned earlier, the inspection of the front brakes requires the removal of the hub from the spindle. This is done by removing the dust cap, retaining pin, spindle nut and retainer. The hub then can be removed. If your inspection is part of the teardown, replace the spindle nut prior to removal of the hub. Once the spindle nut is in place, pull the hub in a quick motion, sliding across the top of the spindle. This action will pull the rear bearing and seal at the same time. Any brake job should include the repacking or replacement of the front wheel bearings.
F100_6.jpg (10835 bytes)This photo shows what a typical worn brake set will look like. Notice the rear shoe lining, it's almost gone. While worn down, it is not into the metal part of the shoe. These were "bonded linings", which mean that the braking material is bonded to the shoes with an adhesive. Another method of securing the linings to the shoes is a combination of adhesive and riveting. Had these linings been riveted, we would have been into the rivets long ago. Many hobbyist prefer the bonded lining due to their longer life. In heavy duty applications such as trucks, riveted linings are recommended.
During your inspection you will notice a lot of brake dust. This coating of dust does help serve as a marker for identifying leaks. Any leaks around the wheel cylinder seals or spindle seals will show up well on this coating. On a teardown, leak identification is not as important as it is during bearing service or other maintenance that causes you to have the drums off. In this photo you can see a little seeping of brake fluid around the front wheel cylinder seal. Take note on the rear brakes of any leakage around the axle seals.
The brake job should always include the rebuilding or replacement of the wheel cylinders. This is an often over looked part of brake work. New linings greatly increase wheel cylinder pressures. This increased pressure will cause a weak cylinder to fail. Kiting a wheel cylinder every 2 or 3 years is a small price to pay for safety and reliability.
F100_5.jpg (9012 bytes)Now we turn our attention to the braking surface. In this photo you can the inside braking surface. The highlighted section shows rivet cuts from a previous set of linings and chatter marks. Most of the minor imperfections can be "Turned" or machined out. The photo below is the opposite side and is in worse condition. Rivet scoring this heavy cannot be cleaned up by machining. Replacement of the drum is the only option in such cases. Drums MUST always be replaced in pairs.
Cast into most drums, is a number that denotes the maximum machining tolerance. A quick measurement shows this drum to be well over the maximum turning tolerance. So, we add new drums to our list of required parts. The rear drum surfaces looked good and had enough material to safely turn.
The front bearings were in good shape, but looked as they had been over-heated a little. The seals were reusable, but with the need for new drums and bearings we decided to go with new seals too. We looked over the brake hardware (springs) and they looked fine, but since we did not know how old they were, we added them to our list as well.
F100_12.jpg (8265 bytes)Parts List & Machine Work:
(2) New Front Drums
(4) Wheel Cylinder Rebuild Kits
(1) Set of Front Brake Hardware
(1) Set of Rear Brake Hardware
(1) Set of Front Brake Shoes
(1) Set of Rear Brake Shoes
(2) Sets of Front Bearings with Races
(2) Front Bearing Seals
(2) New Dust Caps
(2) Turn Rear Brake Drums and Balance.
With classic vehicles, you have another element to deal with. The availability of parts for your application. In some cases the parts are no longer available from local sources and mail order may be your only option. In some cases, the parts may not be available at all. There is hope though.
Discontinued brake shoes can be relined if in good condition. There also may be a "New-Old Stock" source for hard to find applications. Last, you may find that used parts are your only option if you stay with the original braking system. You maybe able to find drums or wheel cylinders that are still in rebuildable condition through local wrecking yards. I would caution heavily against the uses of used brake hardware such as springs, clips, cables and wheel cylinder seals, as these parts cannot be reconditioned.
When faced with limited parts options, you may want to look into upgrading your brake system through the use of aftermarket brake kits. These kits provide the user with modern components and the added safety of advanced design. Many aftermarket kits are offered with a power option not originally available on many older vehicles.
TEAR DOWN & RECONDITIONING
F100_6.jpg (10835 bytes)After safely jacking and supporting your vehicle, remove the wheels and drums. Before you start the teardown you need to clean the brake dust from the backing plate and hardware. On older model vehicles which have been in storage a long time this is most important. Older brakes linings were made of asbestos-containing compounds and this dust needs to be safely removed before work begins.
F100_11.jpg (7530 bytes)There are several ways to clean the brakes before starting work. One, is to pressure wash them with detergent soap and blow dry with compressed air. The method I prefer, is to chemically clean the brakes with Berryman's Brake Cleaner which is available through your local parts store. The cleaning process is done by placing a shop towel or catch pan below the brake and washing the brake down from the top down. The final results leave you with very clean used parts, ideal for tear down.
You should always wear a dust mask during the cleaning phase, whether asbestos is present or not. If you suspect that asbestos is present, you can duct tape a plastic bag to the location, leaving an entry large enough for one hand to run the spray can. Avoid breathing the dust or getting it on you. An old tooth brush can help immensely in the cleaning. Surgical Latex or Rubber gloves should be used if asbestos is suspected while cleaning and handling of the linings.
F100_8.jpg (9238 bytes)After the hardware was removed, we sprayed down the backing plate and wiped clean any residue. The above photo shows the cleaned backing plate. Next, we tanked the hardware in our parts cleaner. Now, not every home shop has the room for a full size parts washer. For years I used Berryman's Chem-Dip in a 1 gallon container. Their 1 and 3/4 gallon containers come with a parts basket like the one shown in the photo. The product works very well on stubborn crud found on brake parts. There isn't much to preparing parts for re-installation other than cleaning and inspecting the parts. This part of the job is still very important and should not be over looked.
Here, you can see we have lubricated the star adjuster with an anti-seize compound to make adjustment easy. This anti-seize lubricate is water resistant and helps prevent the adjuster from rusting as well. Originally a white grease such as Berrymans White Lithium (Part No. 2016) was used to lubricate these parts and is still a good choice for metal to metal applications.
REMOVAL: Block the brake pedal in the released position to prevent its being moved accidentally while the cylinder is off, thus avoiding the loss of brake fluid.
In our case this is a complete teardown so there is no need to perform this next procedure. The following instruction is offered if only the wheel cylinder is in need of service.
Jack up the vehicle and remove the wheel and brake drum. Unfasten the brake line or hose from the wheel cylinder connection. Unhook the brake shoe retracting spring to permit the shoes to be moved away from the cylinder.
At this point, if step bore cylinders are used, note carefully in which direction the larger bore is facing. On some vehicles, the larger bore faces the rear while on others it faces the front. Pay close attention here!
Remove the two screws which fasten the cylinder to the backing plate and remove the cylinder.
DISASSEMBLY: The above is an exploded view of a typical wheel cylinder used with Bendix and Lockheed brakes.
To disassemble, remove the end covers and push out the pistons, rubber cups and spring. Wash all parts in Berryman's Brake Cleaner or clean alcohol, but before doing so, wash your hands with soap and water to avoid the possibility of mineral oil or gasoline products from coming in contact with the parts during assembly.
INSPECTION: Examine the cylinder walls. If found to be scored or rusted, the cylinder must be reconditioned by honing. A hone of the proper size should be placed in the chuck of an electric or battery drill. Work the hone back and forth a few times, then inspect the cylinder to see if the wall is cleaned up. Do not hone any more than is required to remove scores and smooth up the cylinder.
Clearance between the pistons and cylinder wall should be from .002 to .004" when checked with a feeler gauge. If the clearance is more than .004" and new pistons will not provide the correct clearance, a new housing will have to be installed. Always use new rubber parts when reconditioning a cylinder. Rubber parts which are swollen or damaged will seriously impair the proper function of the brakes. Repair kits are available which contain all parts usually required for re-conditioning wheel cylinders.
REASSEMBLE & REPLACEMENT: Dip pistons and rubber cups in brake fluid. Place the spring in the center of the housing, the rubber cups at each end of the spring, with their cupped sides to the spring and the flat face of the cups flush with the piston. (Or. step bore cylinders the spring is tapered, therefore, be sure to place the small tapered end against the smaller piston.) Replace the end covers.
Assemble the wheel cylinder to the baking plate, connect the brake line or hose and hook the brake shoe retracting spring. Install the brake drum and wheel, and bleed the entire brake system.
Next, we move to the re-building of the Hub, but first it has to be removed from the old drum. You can do this yourself with some effort or take it to a machine shop to have it pressed off. Here you can see that we have re-installed the lug nuts on the studs to protect them from accidental damage. Lightly tap the lugs to loosen the hub from the drum. Do not hammer on the hub. The hub is made of cast steel and is too soft for metal to metal contact with a hammer. The studs are slightly pulled through the drum and it is this that holds the drum to the hub. If you find you are having to pound very hard to un-seat the studs, take it to a machine shop to have it pressed off. Damage to the Hub would ruin your day.
F100_14.jpg (5471 bytes)Once the hubs have been removed, we drop them into our parts cleaner to remove any excess grease. Can you believe all this grease!?! YUCK! To save your parts cleaner solution, scrape out as much of the excess grease you can.
After the hub was cleaned up, we then drove out the old bearing races and cleaned up the race area in the hub with some light emery cloth. We also de-burred the dust cap area with a light file. Another quick dip in the parts cleaner to make sure there was no grit or metal particles left after hub prepping. You wouldn't any of these particles to find their way into the new bearings.
F100_16.jpg (9903 bytes) With the hub all cleaned up, we install the bearing races with a bearing driver. This tool is must, it makes the installation a breeze and prevents damage to the race. This tool also doubles as a seal driver where it performs equally well.
Packing of the bearing is simple enough. Start with a good quality of High Temp Wheel Bearing Grease. Place a golf ball size gob of grease in your palm and work it into the back of the bearing (opposite of the race side). F100_15.jpg (8410 bytes)Continue to work the grease in as you rotate the bearing. When you can see grease being pushed out the opposite side all around, the bearing is packed. Wipe the bearing with a thin film of grease so that it coats the entire bearing.
Wipe a thin film of grease over the face of the race and place the inner bearing into the race. Using your finger, wipe another thin film of grease over the back of the bearing and install the seal. Pack and save out the outer bearing until your ready to install the hub onto the spindle. Now to the brakes!
INSTALLING THE BRAKES
I like to lay out the components prior to installing them. This assures me that I have all the parts and helps me remember where everything is suppose to go before I get down on the ground. About this time I dig out the shop manual to make sure I am correct. Unless you have a photographic memory, get a shop manual before you do any work on your vehicle. At the very least, only tear down one side at a time.
Now it's time to mount the shoes to the back-plate and install the brake hardware. Here is where having the right tools can make your job easy or next to impossible.
F100_18.jpg (7597 bytes)In this photo, I sprayed a little White Lithium Grease at the shoe contact pads. This will prevent the shoes from hanging up against the back-plate. Next, install the shoe hold down spring pins through the back of the backing plate. Slip the shoes over the pins one at a time and secure with the hold spring hardware.
Once both shoes have been attached, spread them gently apart at the top and insert the wheel cylinder connecting pins. You may have to push them into the wheel cylinder some to get them to seat. Pull the shoes back up onto the contact pads. Adjust the star adjuster all the way down and install it between the shoes at the bottom. You may need to re-adjust it out just enough to hold it in place. Remember to get the star adjusters back on the correct side of the vehicle. They are handed to each side of the vehicle.
Next, install the anchor plate over the anchor pin at the top of the back plate. Now you're ready to install the self-adjuster. F100_10.jpg (23500 bytes)Dab a small amount of White Lithium Grease on the back of the cable guide and push it into the hole made for it on the shoe. Hook the adjuster lever in the shoe at the bottom and route the cable through it, over the guide and over the anchor pin at the top. Secure the assemble by attaching the adjusting spring to the adjusting lever and fastening it to the opposite shoe.
The cable guide may not stay in place with tension on the adjuster spring. To solve this problem, install the base of the retracting spring through cable guide into the shoe. This should hold it in place under tension. Next attach the opposite side retracting spring to the anchor pin and follow it up with the attachment of the other retracting spring. Pull everything back into place on the contact pads. Adjust down the star adjuster enough to install the drum later.
PUT'N IT ALL BACK TOGETHER
Now that the hub is ready to install, apply a little grease to the seal area and slip the hub back onto the spindle. Push the hub firmly back and slip the outer bearing on. Then install the spindle washer and spindle nut. Torque the spindle nut to the specifications of your application. Next, install the spindle nut retainer and a NEW cotter pin. The parts store goofed on the dust cap size, so we are using the old one until we can get the right size.
If you look close, you can see some of the studs are loose. They have been set in place and await the installation of the new drum.
F100_2.jpg (8430 bytes)Seen here, the new drums were unpainted. This simply would not do. I hate a rusty drum, whether you can see it or not. Also if you look close, you can see the maximum cut information around the front edge of the drum. F100_3.jpg (10575 bytes)The new drums are of superior quality over that of the stock OEM drums. Note, there is no huge counter weight attached to the front like the stock drums. The old drums shimmied at high speed (70+). I discovered this later, when the shimmy disappeared after the brake job was complete. Maybe just a coincidence, I thought? Nope, fact. We took the old drums down to our favorite machine shop and spun them for balance. They were REAL BAD.
F100_20.jpg (11213 bytes)Because you could see the drums through the styled steel wheels, we painted them black so they would disappear. We use VHT High Temp Engine Enamel. We applied 3 light coats and 1 medium gloss coat. They still looked good after a month, so we have hope that the paint will stand up over time.
Then we moved on to installing the drums. We began by setting the drum over the hub and wheel studs. A large flat washer and an old lug nut with some anti-seize was used to pull the studs into the drum face. The studs were tightened in a cross pattern to assure even torquing of the hub and drum. Then the studs were re-checked in order to verify the seating of the drum. We re-torqued the wheels again after about 50 miles to make sure very thing was ok.
Bleeding, or expelling air from the hydraulic system, is necessary each time the fluid becomes so low in the master cylinder that air enters the system. This condition occurs whenever the master cylinder, or a wheel cylinder, or a brake fluid line or hose has been replaced or disconnected·
bleeding.GIF (100069 bytes)Most authorities recommend that the system be bled by starting with the longest line and working successively to the shortest, other sources prefer the opposite method, that is, by starting with the shortest line and finishing up with the longest.
There is some possible advantage in bleeding the longest line first on long wheelbase vehicles in that it may be possible to remove a greater percentage of air in this manner and possibly this is the reason why most sources recommend that the cylinder furthest from the master cylinder be bled first.
Actually, there is no particular reason why it is necessary to bleed the system in any particular order except in the case of certain power brake units which must be bled first. As shown in our article on converting to disc brakes, the remote booster requires bleeding before moving on to the rest of the system.
Whether you start with the longest or shortest line the procedure is as follows:
1. Remove the master cylinder filler cap and fill the reservoir. The reservoir must be kept full or nearly full of brake fluid while bleeding the system. Each wheel has a bleeder valve connection.
2. Attach a bleeder tube to the bleeder valve at this point and place the free end of the bleeder tube into a clean glass jar or bottle. A length of 7/16 vacuum line works well.
3. Place a wrench on the bleeder valve where the bleeder hose is connected and turn the valve to the left (counterclockwise) l/2 to 3/4 turn. This opens the bleeder valve. Always use a flare wrench when working with brake fittings.
4. Slowly depress the brake pedal to approximately the halfway point; then let the pedal return slowly to the release position. Repeat this procedure several times, keeping the end of the hose submerged in brake fluid until the fluid expelled from the bleeder hose is free of air bubbles.
5. When no air bubbles are visible, close the bleeder valve by turning the valve clockwise and remove the bleeder hose.
6. Tighten the valve and test it to be certain that it is seated firmly and there are no leaks.
7. Add new fluid to the master cylinder reservoir and repeat the bleeding process on the other wheels in turn. Never use the fluid drained from the brake system if there is any doubt about it's being clean and free from dirt.
With the wheels still off, expand the star adjuster until you can just turn the drum will both hands. Then, back off the star adjuster 10 to 12 notches. Do all four drums and install the wheels, torque the lug nuts to the proper specifications for your vehicle.
Road test the brake system with a few medium speed stops (45 MPH). Apply the brakes each time with firm, constant pedal pressure. Be careful not to over heat the brakes too much. Next, make 3 or 4 reverse or backing stops to properly adjust the brakes using the self-adjusters.
Now is a good time to take up on the Emergency Brake cables. All that is required, is to take the slack out of the cabling. Be careful not to over-tighten the cables, this could lead to a slight engaging of the brakes, causing them to over heat.
Now you're ready to hit the road.
I hope this information has helped you to better understand what is needed to complete a true "Brake Job". Since the braking system is one of the most complex systems in your vehicle, understanding each components function will help you better perform the maintenance that is required to keep your classic in safe running order. - CTS