You have a couple of options when servicing the rear axle. You can do all the work with the axle installed in the car or remove the axle from the car and perform the work on an axle fixture. Each method has advantages and disadvantages. Are you working on a vehicle hoist or using a floor jack and jack stands? If you are planning to just perform a rebuild that requires replacing bearings and seals, then the axle can stay in the car. If you are going to shorten the axle housing, repaint, or powdercoat the axle, then you need to remove the entire axle assembly from the vehicle.
Since the disassembly process is the same for the 8.8-inch and the 9-inch, the removal process of a generic axle is covered here (see Chapter 3 for the 8.8-inch and Chapter 5 for the 9-inch axle). Chapter 8 discusses upgrading the stock axle on a 1957 Bel Air to a Ford 9-inch, so that vehicle is also used as an example in this chapter.
This Tech Tip is From the Full Book, FORD DIFFERENTIALS: HOW TO REBUILD THE 8.8 AND 9 INCH. For a comprehensive guide on this entire subject you can visit this link:
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The most important aspect of safety is to be aware of your surroundings and take the time to remove any dangerous or hazardous items. In addition, if you have been working for too long and feel fatigued, it is best to stop and get some much-needed rest. The work can wait until the next day.
Keep in mind that many auto components are heavy and care should be taken to avoid dropping them. At times, this means that you want to use some sort of lift assist, such as a jack, or a second person. Make certain that you are using a floor jack and jack stands that are rated for your vehicle. I actually like to get the vehicle as high as possible and use large six-ton-rated jack stands, which allows more room underneath the vehicle.
I often refer to assembly grease to help hold parts together or prelube seals. Always make certain touse a good Type-2 grease, which is readily available at most parts stores. It is also a good idea to have a supply of brake cleaner, RTV, and thread locker.
Always wear the correct eye protection, clothing, and shoes. Remove all jewelry and tie back long hair before performing any service work. If any cutting torches or welding work is required, use the correct eye shields and remove any solvents or dirty rags that may be in the area.
Always have a fi re extinguisher that is up to date and nearby, just in case. There are four classes of fire extinguishers: Class A is for general combustibles such as paper, wood, and cloth. Class B is for fl ammable liquids and greases such as gasoline, oil thinners, and solvents. Class C is for electrical fires. Class D is for combustible metals such as powdered aluminum, sodium, or magnesium. There are also “combination” extinguishers that are rated for several classes. Be sure to have the right type of fire extinguisher for the components you’re working on.
Gear oil, especially used oil, is very stimulating to your sense of smell, or in other words it stinks very badly. If it gets on my clothes, I typically end up just tossing them in the trash and don’t risk putting them in the washing machine. I also like to wear disposable nitrile or similar gloves to make hand cleanup easier and to avoid getting the smelly and oftentimes burned oil on my hands. Once it gets on your hands, it can take days to wear off.
I show some of my homemade specialty tools and purchased tools that are unique and not typically found in the standard mechanic’s toolbox. Some of these are special bearing pullers, pinion flange holding equipment, precision dial indicator, inch-pound torque wrenches, and seal pullers.
Finally, a very important aspect of safety is to keep your work area clean and uncluttered.
The first step is to get the vehicle in the air. If you do not have access to a hoist (I didn’t), jack up the vehicle as high as possible and put jack stands under the frame. This allows the axle to drop freely.
Typically, the shocks are the travel limiters of the axle at full rebound. So, once the vehicle is securely supported by jack stands, remove the shocks. This allows the axle assembly to drop even lower in the chassis. Without the shocks attached, the axle lowers farther, so you can closely inspect the exhaust and brake lines and cables to make certain that they are not the travel limiters. On some vehicles, the brake cables or hoses may have to be removed to allow the axle to drop freely. This is the reason that you want to have the car chassis as high as possible—to allow for this extra travel.
The Tri-Five (1955–1957 Chevrolet passenger car) rear shock arrangement uses an upper shock mount that is accessed from inside the trunk. This upper shock mount arrangement will be replaced with an additional frame crossmember (see Chapter 8).
With the top mounts removed, the lower mounts can be removed next.
I also noticed while underneath the vehicle that the dual exhaust tailpipes had an interesting routing path. When you purchase a classic car that has had multiple owners, the total number of previous repairs and quality of the workmanship over the life of the vehicle can be questionable. Take your time and look things over carefully before you purchase any used vehicle.
With the rear shocks removed, I can turn my attention to removing the driveshaft. Most driveshafts are bolted to the axle pinion flange and just need to be unbolted.
Tri-Five vehicles use a leaf spring style (or Hotchkis) of rear suspension. If your vehicle has a coil-style arrangement, there are some differences for removing the axle from the vehicle. The main one is that there are control arms bolted between the axle and frame or body that need to be removed.
Before beginning the leaf spring removal, remove the brake lines and cables to get them out of the way. This is probably the biggest deterrent to most owners when removing an axle as the brake lines may be excessively corroded and the head of the brake fitting may strip. The parking brake cables may require you to disassemble the brake hardware and shoes to release the cable from within the backing plates. Also, when you re-install the axle, bleed the hydraulic brake system to remove any air from the lines. Make sure that the bleeder screws on the wheel cylinders (if you have drums) or calipers (if you have discs) are not rusted in place before you get to that step.
Brake System Removal Step by Step
Step-1: Remove Shock Stud (Professional Mechanic Tip)
Here you can see the upper shock stud with nut in place just below the back of the rear seat. Typically, a couple of flats are machined into the top of the stud to allow you to grab the stud and keep it from turning while you remove the nut.
If you are installing a fresh set of shocks, you do not need to salvage the threads. Breaking off the stud is a way to remove shocks. Just put a deep well socket on the nut with a long extension in place. Then bend the stud back and forth a few times until it is fatigued and breaks off.
Step-2: Remove Shock Mount (Professional Mechanic Tip)
The lower shock mounts are located on a stud that is welded to the leaf spring mounting bracket. Some axles have the lower shock mount welded to the axle itself. This one shows its age with the amount of rust and bushing deterioration. Unfortunately, I ended up breaking off one of the studs during the removal process. Penetrating oil is the first step for removing rusty fasteners, and when all else fails, use heat from a torch. (See Chapter 8 for stud repair.)
Step-3: Inspect Brake Line Routing
Here you can see the shock with the fl ex hose for the rear brake just in front of it. Notice how the exhaust was routed underneath the brake hose and the hose actually rests on the hot exhaust. This is a perfect example of how not to route an exhaust system. This is an accident just waiting to happen.
Step-4: Inspect Parking Brake Cable Routing (Critical Inspection)
Upon further inspection, I noticed that the parking brake cable was in contact with both exhaust pipes.
Step-5: Remove Strap Nuts
Having a strong coat of oil on the axle pinion seal along with the engine and transmission is fortuitous because the oil on the front of the axle significantly inhibits rust. This axle is a grimy mess from years of oil leaking and road debris sticking to it, but fortunately it hasn’t rusted. Here you can see the typical GM strap–style universal joint retention. There are just four nuts that hold the two straps in place. You can also see the driveshaft’s welded-on balance weight, a couple inches forward of the U-joint strap.
Remove all four nuts from the straps. Then lightly pry the driveshaft forward and remove it from the axle. This vehicle has a slip at the transmission output-style driveshaft, which is typical for most muscle cars. Once you have the driveshaft clear of the pinion flange, pull it out of the transmission and set it aside. Place a drop pan underneath the driveshaft so you’re prepared to catch a small amount of transmission fluid that leaks out of the transmission.
You may have to push the strap partially out of the yoke. These nuts can be a little tricky to access; use a box-end wrench because there is not enough room for a socket and ratchet. It is possible to use a socket with a swivel and extension arrangement on some applications.
Step-6: Remove Cable
The parking brake cable runs through an equalizer bar underneath the car. You just need to pull back the protective dirt boot and remove the retaining clip to the frame bracket. The U-shaped retaining clip has a bent-over tab on the closed end. You can grab this tab with pliers or even tap it with a large-tip screwdriver to remove it. Once the clip has been removed, push the cable housing out of the bracket. There is a slot in the bracket that allows the cable to come free once the cable housing is removed. Repeat this procedure for the other side and then slip the cable out of the center equalizer bracket. (I am not disconnecting the cable from the brakes as I am going to replace this entire axle with a disc brake arrangement with all new cables.)
Step-7: Remove Hydraulic Line
The flexible hydraulic line is the last piece of the brake system that needs to be removed. A bracket is welded to the axle housing that supports the junction block for the brake lines to the individual wheels. This bracket also has an anti-rotation feature, so it’s easy to remove the flexible line. Be sure to clean off the crud and use the correct-size line wrench to remove the brake hose. You need to be careful as brake fluid leaks out when this line is removed. Brake fluid removes paint and damages most surfaces, so be careful as you catch the fluid, and don’t let it get all over your shop.
Leaf Spring Removal Step by Step
Step-1: Remove Fasteners
If your leaf springs have never been removed from the car, it’s not going to be easy. Soak them with penetrating oil for a few hours. If that doesn’t help you may need to resort to heating the bolts with a methylacetylene propadiene (MAPP) gas torch to break them loose. Always be careful when heating the fasteners as any residual penetrating fluid may catch on fi re. It is a good idea to clean all of the penetrant off and never spray penetrant or any fluid on the fastener after it has been heated and is still hot. Using MAPP gas or the equivalent, evenly apply heat to the entire nut and circulate the torch around the fastener to achieve even heating for at least 30 to 60 seconds and then try to loosen the fastener. If the nut is still stuck, apply heat for an additional 30 seconds and try again. If all else fails, keep applying heat until the nut is red hot; it should loosen then. Here, you can see that the second spring in the spring pack appears to have a sharp square end. The spring end actually broke off.
Step-2: Inspect Rear Suspension
This car sits very low in the rear, and this certainly isn’t the stock ride height. The previous owner lowered the car and decided to use a torch to heat the springs until the car sank the required amount. The V-shape in the top leaf is not a production design; rather, it is from the torch action. The second leaf was even cut off to further allow the top leaf to flatten out and the rear suspension to lower. This is another perfect example of how not to perform a task on your car, such as lowering.
Step-3: Remove Leaf Spring Nuts (Professional Mechanic Tip)
Long U-shaped bolts fasten the leaf spring pack to the axle. There are a couple options to remove them. You can just turn the nuts until the U-bolts break or you can try to save the nuts. To save the nuts, heat them with MAPP gas, which produces a much hotter flame when compared to traditional propane. It usually comes in yellow containers as compared to the blue propane containers and is available at most hardware stores. MAPP gas is more convenient to use than oxyacetylene. Evenly apply heat around the nut until it turns red hot. This typically takes a minute or so; while the nut is still hot, try to loosen it. If the nut is still stuck in place, continue to apply heat until it loosens. Once the nut begins to loosen, make certain to completely remove it or otherwise, as it cools, it may shrink and seize in place again.
Step-4: Remove Leaf Spring Shackle Bolts
Leaf spring shackle bolts probably don’t want to come apart either. You can use heat to help get the fasteners off. Then pry the shackles off. My bushings were ruined from the heat, but I have to replace the leaf springs anyway. (See Chapter 8 for more on spring shackle brackets.)
Step-5: Remove Spring
Once the outer shackle is out of the way, pry the spring off the stud. These springs may be corroded in place and need some extra effort to get them out of the vehicle. Be careful and make sure that the axle is supported when you are removing the springs, as they should be the last piece that is holding the axle in the car.
Step-6: vInspect Vent Hole
After you remove the axle, keep the parking brake cables in place. Also leave the wheels and tires on to make it easier to move around the shop without the aid of a jack or second person. Inspect the vent hole on the driver-side axle tube. I discovered someone had removed the vent cap and never replaced it, so this axle was leaking fluid out the vent, and road debris and water was entering the axle—another reason to replace the entire axle.
Step-7: Clean Vent Hole
If your axle will be completely disassembled and thoroughly cleaned, use a wire brush to remove any vent hole debris. Of course, some of this debris may fall in the hole but you can clean it out later. Note that the jounce bumper mounts to the axle, and a small tab is welded on top of the axle to help locate the bracket. The other side of the bracket is held in place under the U-bolt. The U-bolt mounting pads are on the bottom of the axle tubes and the leaf spring pack goes underneath the axle. As a result, this is called an underslung-style mounting arrangement. Some axles have the leaf spring mounted on top of the tubes and are called overslung.
This is the brake junction block mounting bracket. The mounting hole is an oval shape that keeps the block from rotating. You can also see the tab for the jounce bumper bracket to the right of the brake line bracket.
Written by Joe Palazzolo and Republished with Permission of CarTech Inc