Mustang Restoration Chapter 5: Engine and Transmission

The most important function of any vehicle is being able to drive. More specifically, being able to drive safely. That's why mechanical restoration is the most important stage of any project.

Of the many parts that are required to drive your Mustang, the engine and transmission are two of the most complex. Decisions about these two items will affect the rest of your restoration.

No matter what condition your engine and transmission are in, there are options that will allow you to finish your project. Once your engine and transmission are completed, you'll have a better idea of what you'll need for the rest of your build as well, since these decisions will impact everything from your exhaust to your suspension.

You may have heard that you should restore the body of your Mustang first. But completing the body restoration first makes the mechanical steps significantly more challenging. Removing the engine and transmission from a vehicle isn't a small feat. It's not unusual to cause minor body dings and paint scratches during the process.

Your engine evaluation gave you answers that will be invaluable at this stage. If your engine is in tip top condition, then all that's needed is a filter and fluid replacement. Replacing your rubber hoses and seals would be a good preventative measure as well. Of course, you can remove and replace it if you want, but you can also comfortably leave it in place and move on to the next section as well.

Covered In This Chapter

• Removing Your Engine and Transmission - Preparing your engine and trans for removal and then lifting
• Engine Options - How to determine if your engine can be rebuilt and selecting a replacement if needed
• Transmission Options - Evaluating your transmission to see if it should be replaced

Removing Your Engine and Transmission

Whether you're getting it rebuilt, replacing it, or just getting it out of the way, you'll need to remove your engine. You'll want to remove the transmission as well. These two items are connected and are two of the most intricate parts of your Mustang. Removing them so you can get clear visuals and space to work will make your restoration significantly easier.

You should have already drained your transmission fluid, coolant, and engine oil. If you haven't yet, you'll want to perform those steps first. Draining will make these parts easier to work with and prevent messes. You can head back to chapter four for guidance on draining these fluids if you need it.

Before lifting your engine and transmission, you'll need to carefully disconnect all the hoses, components, and accessories.

What Needs to Be Disconnected

Remove Shifter Assembly

If you have an automatic transmission, all you need to do is disconnect the shifter from your transmission. Once that's done, you can skip ahead to the next step.

If you have a manual, this is still very simple. First, remove the metal plate. The protective boot is held on by four 7/16” screws that need to be removed. The easiest way to do this is to push the boot to the side and go in underneath with a ratcheting wrench.

Underneath the boot, there are two more bolts holding the shift lever in place. Remove those. Remember to store the screws and bolts carefully; you'll want them later.

Once you've removed the shifter assembly, it's time to move underneath your car.

Remove the Exhaust System

Removing the exhaust first makes the rest of the disassembly easier. Disconnecting and removing these components gives you more space. Also, you won't need to try to reach over and under them.

If you're not going to reuse the exhaust, cutting it is a great way to save yourself some time.

Disconnect the Driveshaft

In the rear of your Mustang, the driveshaft will be held in place by four retaining bolts on the U-joint. Remove these and store them safely.

Once the driveshaft's retaining bolts have been removed, it should easily pull out. It's important to handle the driveshaft with care. Even minor dents and dings can cause driving and safety issues. Store your driveshaft carefully.

Remove the Starter

First, remove the electrical connector(s). With the battery removed, this should be safe. The starter itself will be held in place by two bolts.

Though the bottom bolt is easy enough to reach, you may need a wrench extension for the upper bolt. Once the bolts are removed, you should be able to slide the starter out and store it.

Disconnect Electrical Components

Take your time finding the many small wires and sensors connected to the transmission. Photograph these and then disconnect them.

You'll be disconnecting the speedometer sensor, the parking brake linkage, and the equalizer bar or kickdown linkage. For the equalizer bar and clutch bar linkage, you'll need to use needle-nose pliers to remove the cotter pin.

Remove Crossmember

There's a crossmember holding your transmission in place. The bolts holding the crossmember tend to be some of the most rusted. There's usually little reason to remove this part, so the bolts have probably sat in place for fifty years. Use penetrating oil to soften up the rust around the bolts so they're easier to remove.

Remove the nuts from the bolts but leave the bolts in place. You'll need to support your transmission before you remove the crossmember.

Some people wait to remove their crossmember until the engine and transmission are attached to the hoist. Others support the transmission with a hydraulic jack. Neither approach is wrong.

Remove the Radiator and Fan

Before removing the radiator, be sure that your coolant is drained. Then remove the upper and lower hoses.

Remove the fasteners on the left side of the fan shroud and then pull it over the fan. Remove the fan bolts and the fan. Then you can remove the shroud.

The radiator has four mounting bolts you'll need to remove before pulling the radiator. If you're lucky enough to have an original radiator in good condition, take your time removing it. But for most people, it's worth it to buy a new radiator. They're inexpensive, and no one wants to risk an engine overheating due to a faulty radiator.

Under the Hood

Underneath your hood (or where your hood once was) there's another list of items to disconnect. As you're disconnecting, check for chew marks or other signs of abnormal wear.

Disconnect Kick Down Linkage

You'll find the throttle kick down linkage on the rear-end of the engine, closest to the windshield. Disconnect this.

Fuel Line, Heater Hoses, Ignition Coil

Towards the front of the engine, you'll find the fuel line connected to your carburetor, several heater hoses, and your ignition coil. Disconnect them all. There's no great trick to removing them other than to move carefully. If something resists being moved, use penetrating oil and wait a few minutes before trying again.

Once everything's disconnected, it's time to lift your transmission and engine out of your Mustang.

Lifting the Engine and Transmission

Just because an older engine is smaller, don't imagine that it will be lighter. A modern engine and a vintage V8 both come in at well over 400 pounds. No matter how in shape you are, you'll need professional equipment to remove your engine safely.

What You'll Need to Lift Your Engine

The best option is a cherry picker or similar engine hoist. Since it's likely you'll only use this a few times, you'll probably want to borrow or rent one. If you do need to buy, they aren't too expensive.

Even if you buy the nicest engine hoist in the world, it will still be less expensive than a single back injury. This is worth considering, since most of the other engine removal methods can cause injury.

In addition to an engine hoist, you'll need assistance for the actual process of lifting your engine. One person can use the hoist while the other guides the engine out. This helps ensure nothing is damaged while removing the engine.

A lift plate makes it easier to pull your engine. While there are a lot of different lift plates, a carb lift plate will be the easiest for classic Mustangs. Basically, this attaches to your engine in place of your carburetor. Then you can attach your hoist and lift. Some people also use chains to connect to the front and rear of the engine.

Once your engine is securely connected, you can begin the process of raising it.

Typically, you'll want one individual to work the hoist itself, while another repositions the engine, checks for missed connections, and helps to guide it out.

Eventually, the engine and transmission will come out.

If you elect to use the beam of a garage for a pulley, make sure it's strong enough first.

Engine Options

If you have significant issues, then there are a few options.

Engine Rebuilds

Getting your original engine rebuilt and machined is the easiest option but can be expensive. The pros of this selection are pretty straightforward. You have an expert working on the engine while you push through the rest of the restoration. Though it isn't a guaranteed outcome, it's pretty close.

For many, though, rebuilding the original engine is an important part of the restoration process. At least part of the draw of classic car restoration is getting the hands-on experience of working on your own car. For some, that includes every component, right down to the pistons.

There's no shortage of work to be done with a restoration. Even if you choose to get a shop to help with the engine rebuild, there's still plenty of work.

At the end of the day, they're called combustion engines because they're powered by millions of contained explosions. Engine work done improperly can turn tragic pretty quickly.

If you've never rebuilt an engine before but think you would like to, a good first step is to talk to a fellow Mustang enthusiast who's done an engine rebuild. The best thing you can get is a pair of experienced eyes and hands guiding you through the process.

No matter how experienced you or your friends are, you'll need to find a professional shop to do some of the engine work. There are a fair number of tools required, like a crankshaft damper puller, that are single-duty tools you'll never use again. These tools tend to be expensive. Other work, like boring and honing your engine block and cylinders, requires professional equipment.

Engine Replacements

Replacing your original engine with its perfect duplicate is more of a hunt. If you live near a parts yard and really love digging through old sheet metal, why not? Just be sure to get a tetanus shot first and stay on good terms with the owner. Parts yard owners can help you on your hunt. But only if you're someone they want to help.

A period-correct but not exact replacement is a little easier and has some upsides. Say you were able to find a V6 Mustang, but you really wanted a V8. This is a great opportunity to swap in a period-correct V8 engine. It's not a particularly challenging swap, and because it's so popular, there are many guides on how to do it.

Keep in mind that if you do upgrade your V6 to a V8, you'll also need to trade out your transmission, driveshaft and rear axle, radiator and water pump, and intake and exhaust. Depending on the engine you select, you may also need to reevaluate your fuel system and suspension components.

Period-Correct Engines

First-gen Mustang buyers usually had a choice between four engines: a six-cylinder base option, a two-barrel carburetor V8, a four-barrel carburetor V8, and a high-performance four-barrel V8. The six-cylinder and two-barrel V8 account for nearly 70% of first-gen Mustangs.

Inline Six-Cylinder

The six-cylinders of the era were all grouped together into the “Thriftpower” engine family. These inline-six engines offered a perfect blend of performance and fuel-efficiency.

Through the years, the six-cylinder option grew, starting as a 170 CID version in 1964, and eventually becoming a 250 CID version by 1969.

The great news is that if you have a Thriftpower engine, millions of them were produced. From 1960-1984, Ford put Thriftpower engines into Econolines, Falcons, Mustangs, Broncos, Granadas, and Comets.

Though the Thriftpower never came in any displacements larger than the 250 CID version, it provided enough horsepower to move a lot of vehicles.

Small-Block V8s

Until 1967, the only V8s that the Mustang could come equipped with were small-block V8 engines. Though some hear “small-block” and hear low power, that couldn't be further from the truth. The original Shelby GT350R that helped establish the Mustang as a performance vehicle had a small-block V8 in it. So did the notable Boss 302.

Though these were small block V8s, they came in a wide range of displacements, some of which were still large. The horsepower speaks for itself, though.

The best part about Ford's small-block V8 engines is their abundance. These engines were in continuous use from 1961-2001 and are still available today as crate engines.

In short, if you'd like to find a period-correct V8 engine for your Mustang, all you have to do is look.

Restomod Options

Period-correct options are definitely the most popular for restorations. But modern engines offer a lot of benefits, especially when it comes to horsepower. The most popular modern engine swaps are LS engines and Coyote engines.

Coyote Swaps

Coyote swaps can be difficult, but the horsepower and brand compatibility are hard to beat. The main thing that makes Coyote swaps difficult is their size. If you think this is the route that you'd like to go, then you may want to seriously consider getting a '67 or later. The introduction of big block engines means it's easier to find parts to support a Coyote swap for these years.

From the brakes to the fuel rails, you'll need to rethink every part of your build. But if you're willing to commit, it's more horsepower than the first-gen Mustang ever had.

Modular 5.0 Swaps

Ford made a lot of other great V8s before the Coyote. Overhead cam engines became standard starting with the 1996 Mustang GT. Modern versions of many of these engines continue to be in production and are sold as crate engines. Crate engines make it easy to install a new engine in your Mustang by offering a turn-key solution to the engine installation.

LS Swaps

LS swaps are popular primarily because of how easy they are. That said, LS swaps are still one of the least popular options for classic Mustangs. Whether that's because LS engines are GM products or it's because there are other engine options that excel in almost any area the LS engine does well in.

One of the reasons LS swaps are easy is because they're an overhead valve configuration modern engine. That makes them very small. There are a lot of different LS engines to choose from, all with their own pros and cons.

Transmission Options

Once you've decided what to do with your engine, you'll be able to decide on your transmission. If you have to remove your engine, then you may as well pull the transmission as well. Even if your transmission is in great shape, there are a few things you'll want to replace.

Stock Transmissions

All automatic first-gen Mustangs used the C4, or Cruise-O-Matic, transmission. These transmissions don't have many features, but they do have a respectable torque capacity and are easy enough to work on. This makes them relatively desirable for restorations.

The C4 was in use from the Mustang's debut through 1984, so there's no shortage of options. Ford also used the C4 transmission in a variety of vehicles, not just the Mustang. That means you can find a C4 in good condition at most scrapyards, and many C4 parts are still made today.

The manual situation is a little dicier.

The manual transmissions used in early Mustangs were all “top loaders.” These simple manual transmissions were in use until 1979, when the SROD was introduced.

The manual options at the time were a three-speed and a four-speed. If you selected the three-speed, you had the extra option of selecting “synchro smooth.” While all the manual transmissions had synchronizers in second and third gear, the synchro smooth option added a synchro in first gear.

The four-speed manual was a sports-type transmission with a close or wide gear ratio.

Rebuilding Your Transmission

As long as there's no large-scale damage, rebuilding your transmission is an option. If your transmission is in poor condition but needs to be rebuilt, your best and easiest option will be to send it to a shop.

Just like engine work, transmission work requires precision, and there's a long list of things that can go wrong. It also requires specialized tools that aren't cost-effective investments. It's a complicated enough area of specialty that there's more to say about it than would fit in a book.

In a transmission rebuild, you'll be replacing the internal components that no longer work. In that regard, it's much like getting a brand new transmission. A rebuild is usually less expensive than buying new, as long as you're only replacing a few parts.

Many shops specialize in transmission rebuilds. Because of the delicacy of transmission repair, you'll want a shop with an outstanding reputation.

Restoring Your Transmission

Before you get started, it's time to give your transmission a good wash. Engine degreaser and hot water are all you should need to clean away the gunk that's accumulated over the years. A clean transmission is easier to check for issues, and you're less likely to have issues with debris during the restoration.

Assuming your transmission hasn't had any work done, there are a few things you can count on needing to do.

Gaskets and rubber seals degrade with age. Replacing them is an easy way to keep a transmission in good condition.

Transmission rebuild kits are perfect for this application. Most transmission rebuild kits come with:

Master Rebuild Kits will also come with synchro rings, and there are additional parts in more advanced kits.

These kits and your factory service manual will walk you through replacing each gasket, seal, and bearing. It's important to get every piece just right to prevent major issues from occurring. Photographs are an easy way of making sure that new parts go on exactly where old parts were.

When replacing gaskets, make sure to completely remove all the previous gasket's seal. A wire brush and adhesive remover are the two easiest tools for this. A clean surface is easier for the new gasket's adhesive to form a firm seal with. With just a little extra work up front, you can have a working gasket for another fifty years.

There are a couple of extra parts you should consider replacing. These will mostly affect the driving experience.

If you have an automatic, you can flush your torque converter and change the fluid. Otherwise, the torque converter should still be in great condition.

If you're working on a manual, then you should consider replacing your clutch and replacing or resurfacing your flywheel. Even the best driver in the world has caused some damage to their clutch over time.

You can tell that a clutch is damaged when it feels spongy or smells like it's burning. A damaged clutch will also prevent you from getting the kind of smooth shifts that you want.

Replacing Your Clutch

Inspect your existing clutch plate. Some problems can be caused by larger issues that you'll want to address. Simply replacing the clutch won't solve these issues, and your new clutch will likely suffer the same fate as the one you're replacing.

Items to check for:

• Is oil present on your existing clutch plate?
• Is there abnormal wear and tear or twisting to the splines on the input shaft?
• Is there grease or dirt built up on the flywheel or input shaft?

If so, there may be more serious issues you should investigate. If not, then a clutch installation should fix your shifting issues.

First, you'll want to remove any oil or grease that exists on the friction surfaces. This could cause serious issues later.

When you place the new clutch disc on your transmission's input shaft, it should be able to move freely. You'll use a clutch alignment tool to make sure that everything is where it should be. Then, simply bolt the clutch on in place of the stock one. Once again, your factory service manual is your go-to reference source on this.

Replacing Your Transmission

Many people decide to replace their classic Mustang's transmission, even if it's in perfect condition.

Transmissions with overdrive gears are better for people who plan to drive their Mustang regularly. Overdrive gears are designed for highway cruising and help your Mustang get better fuel economy.

For manual transmissions, one of the easiest replacements is the T5 5-speed transmission. Not only is it easy to find, it's also easy to work on, and a great substitute for any first-generation manual.

There are many guides for how to perform a T5 conversion, and T5 conversion kits are sold in a variety of places. These kits include everything you need for a perfect conversion.

For automatic transmissions, the AOD is as good as the C4 in every way, but it's newer and has an overdrive gear. Unless you really want your restoration to be period-correct, there aren't any downsides to these replacements.

If you're planning on upgrading to a Coyote engine or creating a drag beast, then you'll need to look at modern transmissions that can handle the torque.

Newer transmissions have higher torque capacity ratings. If you want something that looks like a T5 and that's easy to work on, Tremec actually makes modern T5 variants. These transmissions have higher torque capacities but are otherwise T5s.

Your Transmission and Engine

Every other mechanical decision you make during your build will be determined by your choices at this stage. In particular, your driveshaft and rear axle selections will be affected by how much horsepower you plan to create. Though there's no wrong way to go, each option does impact your journey.

Check out our full Classic Mustang restoration guide to learn everything you need to tackle your next project.